BlackjackSharps

Blackjack Mathematics Glossary

Every term a blackjack sharp needs — from house edge and expected value to deck penetration and true count, explained in plain language.

64 terms across 4 categories • Schema.org DefinedTermSet Validated
Topic illustration: Blackjack Mathematics Glossary
Illustration of the topic; rules and assumptions are explained below.
2
21+3 (21+3, Twenty-One Plus Three)
Side Bets, Bankroll & Mathematical Expectation
A side bet that forms a three-card poker hand from your first two cards plus the dealer upcard. A common live paytable is: suited trips 100:1, straight flush 40:1, three of a kind 30:1, straight 10:1, flush 5:1. House edge is typically 3–4% depending on paytable and number of decks, roughly 6–8 times the cost of the main game.
Example: At the table: you bet $5 on 21+3 and are dealt 7♠ 8♠, with the dealer showing 9♠. That straight flush pays $200 at 40:1, but about 96 of every 100 side-bet dollars come back over the long run.
3
3-to-2 Payout (3:2, Full Pay Blackjack, Standard Blackjack Payout)
Table Selection & Felt Rules
The standard payout for a natural: you win 1.5 times your bet. Naturals occur on about 4.75% of hands in a 6-deck shoe, so 3:2 is worth roughly 1.4% more to the player than 6:5. Treat it as a non-negotiable table filter.
Example: At the table: a $20 bet on A-K pays $30 profit at 3:2 versus $24 at 6:5. Over 100 hands at $20, that gap costs about $28 in expectation.
6
6-to-5 Payout (6:5, Short Pay Blackjack, 6:5 Blackjack)
Table Selection & Felt Rules
A reduced payout for a natural: 1.2 times your bet instead of 1.5. It adds about 1.4% to the house edge, which is more than H17, no DAS and no surrender combined, and it wipes out any realistic card-counting edge.
Example: At the table: a $25 bet on A-Q pays $30 instead of $37.50. A game with a house edge of about 0.5% at 3:2 becomes roughly 1.9% at 6:5. Walk away.
A
Auto-Stand (Auto Stand, Default Stand)
Online, Live Streams & Game Variants
Software behavior that stands your hand automatically, either on any 21 (harmless) or when the decision timer expires (potentially costly). On timer expiry it erases hits, doubles and splits that basic strategy requires. Some lobbies let you change the default; check the settings before playing.
Example: At the table: you hold A-6 vs dealer 5 and get distracted. The timer expires and you auto-stand on soft 17, giving up a double that basic strategy calls for. Standing on soft 17 is clearly worse than doubling here.
B
Bet Behind (Back Betting, Behind Bet)
Online, Live Streams & Game Variants
A wager placed on a seated player's hand. You inherit that player's hit and stand decisions, and depending on the platform, doubles and splits are matched automatically or optionally. Your EV therefore depends on their skill. A basic-strategy player keeps the house edge near 0.5%, while a 'never bust' player pushes it to roughly 4%. Bet Behind lets unlimited players join full live tables.
Example: At the table: You place $20 behind seat 3. If that player stands on every 12–16 regardless of the upcard, your expected cost is about $0.80 per round instead of about $0.10. Watch 10–15 rounds first, and skip anyone who refuses to double 11 or stands on 12–16 against a 7 through Ace.
Blackjack Switch (Switch, Two-Hand Switch Blackjack)
Online, Live Streams & Game Variants
You play two equal hands and may swap their second cards. The switch is paid for with two rules: blackjack pays 1:1, and a dealer 22 pushes all non-busted hands except naturals. House edge is about 0.5–0.6% with correct play. Switching decisions are made by comparing the combined EV of both hand pairings.
Example: At the table: you are dealt 10-6 and 5-10. Switching gives you 10-10 and 5-6, which is 20 plus a doubling hand of 11, far better than two 16s.
Bust (Break, Busted, Over)
Player Actions & Hand Totals
A total over 21, which is an automatic loss. The player acts first, so a player bust loses even if the dealer would also have busted; this sequencing is the source of the house edge. The dealer busts about 28% of the time overall, about 42% when showing a 5 or 6, and roughly 21-23% when showing a 10.
Example: At the table: you hit hard 15 vs dealer 10, draw a 9 for 24 and lose $25 immediately. The dealer then flips a 6 and busts too, but your bet was already gone.
Bust It (Bust It!, Dealer Bust Bet, Buster Blackjack)
Side Bets, Bankroll & Mathematical Expectation
A side bet that wins only if the dealer busts, with payouts scaled by the number of cards in the busted hand. A sample paytable is: 3 cards 1:1, 4 cards 2:1, 5 cards 9:1, 6 cards 50:1, 7 cards 100:1, 8+ cards 250:1. The dealer busts about 28–29% of the time overall, and house edge typically runs 5–10% depending on paytable and S17/H17.
Example: At the table: you bet $5 and the dealer draws 6-2-3-4-9 to bust with 5 cards, paying $45. In roughly 7 of every 10 rounds the dealer does not bust and the $5 is lost.
C
Contribution Percentage (Game Weighting, Wagering Contribution)
Side Bets, Bankroll & Mathematical Expectation
The share of each bet that counts toward a wagering requirement, set per game type. Slots usually count 100%, while blackjack typically counts 0–20% because its house edge is low. Effective turnover = required turnover ÷ contribution rate.
Example: At the table: you have $2,000 of playthrough left and blackjack counts 20%. You must bet $10,000 on blackjack; at $25 per hand that is 400 hands, costing about $50 at a 0.5% edge.
CSM (Continuous Shuffling Machine) (Continuous Shuffling Machine, Continuous Shuffler, CSM)
Table Selection & Felt Rules
A machine that shuffles discards back into the pack after every round. Penetration is effectively zero, so card counting has no value. It also removes shuffle breaks and adds roughly 20% more rounds per hour, which raises your hourly expected loss even though the per-hand edge barely changes.
Example: At the table: at $25 per hand and a 0.5% house edge, 70 rounds per hour costs about $8.75, while a CSM at 85 rounds per hour costs about $10.60. Batch shufflers that prepare whole shoes offline are not CSMs.
Cut Card (Cut Card, Shuffle Card, Plastic Card)
Table Selection & Felt Rules
A colored plastic card placed in the shoe to mark the reshuffle point. Its position defines penetration. When it comes out, most casinos finish the current round and then shuffle.
Example: At the table: in a 6-deck shoe the cut card sits about 1.5 decks (78 cards) from the back, so 234 of 312 cards (75%) are dealt. Track how deep each dealer cuts, because some consistently cut deeper than others.
D
DAS (Double After Split) (Double After Split, DAS, Doubling After Splitting)
Table Selection & Felt Rules
A rule allowing you to double down on a hand created by splitting. It is worth about 0.14% to the player in a 6-deck game and makes more splits profitable: 2-2 and 3-3 vs 2-7, 4-4 vs 5-6, and 6-6 vs 2-6.
Example: At the table: you split 4-4 vs dealer 6 for $25 per hand and catch a 7 on the first hand. That is hard 11 vs 6, so double it to $50.
Decision Timer (Action Timer, Countdown Clock)
Online, Live Streams & Game Variants
The countdown, typically 8–15 seconds in live online games, within which you must act on a hand. When it expires, the software applies a default action, usually stand, and that default can be a costly strategy error. Lag, multitabling and indecision are the main causes of expired timers.
Example: At the table: you hold 12 vs dealer 3 and your connection stutters. The 10-second timer runs out and you auto-stand, even though basic strategy says hit. Repeated over hundreds of hands, these lapses noticeably raise your effective house edge.
Double Down (Double, Doubling Down, DD)
Player Actions & Hand Totals
To double your original bet in exchange for exactly one more card. It is the main tool for pressing favorable spots: hard 11 vs 2-10, hard 10 vs 2-9, hard 9 vs 3-6, and soft doubles such as A-7 vs 3-6 (6-deck S17). Some rules restrict doubling to totals of 9-11 or 10-11.
Example: At the table: $25 on hard 11 vs dealer 6. Place another $25 beside the original bet and take one card. Expected value rises from about +$8 if you hit to about +$16 if you double.
Double Exposure (Face Up 21, Dealer Exposure)
Online, Live Streams & Game Variants
A variant in which both dealer cards are dealt face up, removing all uncertainty about the dealer's hand. To pay for that information, blackjack pays 1:1 and the dealer wins all ties (a player natural usually still wins ties). House edge is about 0.6–0.7% depending on rules. Strategy changes drastically because you know the dealer's exact total.
Example: At the table: the dealer shows 10-6 (16) and you hold 18. You stand, because any hit risks a sure-good hand. With 12 vs dealer 20, you must keep hitting, since standing loses outright.
E
Early Payout (Early Payout Blackjack, Cash Out, Hand Buyout)
Online, Live Streams & Game Variants
An option, best known from Evolution's Early Payout Blackjack, to end a hand immediately for its calculated expected value minus a small commission. The game's RTP is about 99.5%. Taking the payout never increases EV; it only trades variance for a slightly worse average result.
Example: At the table: you hold 16 vs dealer 10 on a $100 bet, a spot worth about -$54 if you play it out. The early payout offers roughly $45 back. That locks a $55 loss with zero variance, slightly worse than playing it out.
ENHC (European No Hole Card) (European No Hole Card, No Peek, ENHC)
Table Selection & Felt Rules
A rule set in which the dealer takes no hole card until all players have finished. If the dealer then makes blackjack, you lose everything wagered, including doubles and splits, unless OBO (original bets only) applies. It costs about 0.11% and changes strategy: do not double vs 10 or ace, and do not split A-A or 8-8 vs ace.
Example: At the table: you double $25 on 11 vs dealer 10 and the dealer draws an ace for blackjack. Under ENHC you lose $50, not $25, which is why the correct play is simply to hit.
Even Money (Even Money Payout, Take Even Money)
Side Bets, Bankroll & Mathematical Expectation
An offer to take a guaranteed 1:1 payout on your blackjack when the dealer shows an ace. Mathematically it is identical to insuring a blackjack. Declining yields about 1.5 × 69% ≈ 1.04 units on average versus a fixed 1.00, so taking even money costs about 4% of the bet. Take it only when your count justifies insurance.
Example: At the table: you have a $100 blackjack against a dealer ace. Even money pays $100 now. Declining averages about $104, paying $150 when the dealer lacks blackjack and pushing when the dealer has it.
Expected Value (EV, Expectation, Mathematical Expectation)
Side Bets, Bankroll & Mathematical Expectation
The probability-weighted average result of a decision or bet: EV = Σ (probability × outcome). It is the long-run average per play, and every strategy decision is simply choosing the option with the highest EV. Hourly EV = average bet × hands per hour × edge.
Example: At the table: you bet $25 at a 0.5% house edge, so EV is -$0.125 per hand. At 100 hands per hour that is -$12.50 per hour. Adding a $5 Perfect Pairs bet at a 4.1% edge adds another -$20.50 per hour.
F
First Base (First Seat, Seat 1)
Player Actions & Hand Totals
The seat immediately to the dealer's left, which receives cards first and acts first. Seat position does not change basic-strategy expectation. It only reduces how many other players' cards you see before deciding, which matters for card counters using index plays.
Example: At the table: At a full 7-seat table, first base decides 16 vs 10 having seen only 3 cards: two of their own plus the upcard. Third base will have seen at least 12 more. For a basic-strategy player, both seats carry the same house edge of about 0.5%.
Free Bet Blackjack (Free Bet BJ, Push 22 Blackjack)
Online, Live Streams & Game Variants
A variant with free doubles on hard 9, 10 and 11 and free splits on all pairs except tens. The casino stakes the extra bet: if the hand wins, you collect on it, and if it loses, you lose only your original stake. The price is the Push 22 rule: a dealer total of 22 pushes every non-busted hand except naturals. House edge is about 1.0% (6 decks, H17), roughly double that of a good classic game.
Example: At the table: with $25 on hard 10 vs dealer 9, you take the free double and win. You collect $50 while risking only $25. Later you stand on 20 and the dealer makes 22, so you push instead of winning $25.
H
H17 (Dealer Hits Soft 17) (Hits Soft 17, H17, Dealer Hits Soft 17)
Table Selection & Felt Rules
A rule requiring the dealer to draw on soft 17. It raises the house edge by about 0.2% in shoe games, because the dealer improves soft 17 more often than she busts it. Strategy changes: double 11 vs ace, double A-7 vs 2, and surrender 15 and 17 vs ace when surrender is offered.
Example: At the table: the dealer turns A-6, draws a 3 for 20 and beats your 19. If the felt reads 'Dealer must hit soft 17', budget about $0.20 of extra expected loss per $100 wagered.
Hard Hand (Hard Total, Hard Hand)
Player Actions & Hand Totals
Any hand with no ace, or with aces that must be counted as 1 to stay at 21 or below. Hard 12-16 can bust with a single card, and hard totals are where most strategy errors happen.
Example: At the table: 10-6 and A-5-K are both hard 16. Against a dealer 7, hit despite the 62% bust risk, because standing on 16 vs 7 wins only about 26% of the time.
Heat (Casino Heat, Pit Heat, Scrutiny)
Table Selection & Felt Rules
Increased casino scrutiny of a suspected advantage player. Signs include the pit boss watching, a surveillance call, frequent shuffles, flat-bet restrictions, a back-off or a trespass warning. Heat is triggered mainly by bet sizing that tracks the count, not by winning itself.
Example: At the table: you jump from $25 to $300 right after a run of small cards. On the next shoe the dealer shuffles at 50% and the floor asks for ID. That is heat: color up and leave before you are backed off.
Hit (Draw, Take a Card, Hit Me)
Player Actions & Hand Totals
To take another card. You may keep hitting until you stand or bust. Basic strategy hits hard 12 vs 2-3, hard 12-16 vs 7 through ace, and any total of 11 or less when doubling is not correct.
Example: At the table: hard 12 vs dealer 2. Hitting busts 31% of the time (4 of 13 ranks are worth ten), but standing loses more often. Tap the felt, or scrape your cards in a face-down game.
Hole Card (Down Card, Dealer's Face-Down Card)
Player Actions & Hand Totals
The dealer's face-down second card. In US-style games, the dealer peeks when showing a 10 or Ace and ends the round immediately on a blackjack, so you never lose double or split money to a natural. In European No Hole Card (ENHC) games, the second card is dealt after players act. Losing all doubled and split bets to a dealer blackjack adds about 0.11% to the house edge.
Example: At the table: The dealer shows an Ace. The chance the hole card is ten-valued is about 30.8% (4/13, infinite deck). That is below the 33.3% breakeven for 2:1 insurance, so insurance has an EV of about −7.7% of the side bet. Decline it.
I
Infinite Blackjack (Evolution Infinite Blackjack, Common Draw Blackjack)
Online, Live Streams & Game Variants
Evolution's live game with unlimited seats. Every player receives the same first two cards against the same dealer upcard, then decides individually. Extra cards are dealt one at a time, from a single shared sequence, to every player who chooses to hit. The game uses 8 decks with shallow penetration, so counting is impractical. Rules include dealer stands on soft 17, blackjack pays 3:2, one split per hand, and Six Card Charlie: six cards without busting win automatically. The published RTP is about 99.47%, a house edge of about 0.53%, with optimal play.
Example: At the table: You hold 2-3-4-2-3, a five-card 14, vs a dealer 10. Standing wins only if the dealer busts (about 23%), so its EV is about −0.54. Hitting wins on any Ace through 7, which is 28 of 52 cards or about 53.8%, thanks to Six Card Charlie, for an EV of about +0.08. Hit.
Insurance (Insurance Bet, Dealer Ace Insurance)
Side Bets, Bankroll & Mathematical Expectation
A side bet of up to half your main wager, offered when the dealer shows an ace, that pays 2:1 if the dealer has blackjack. It breaks even only when exactly 1/3 of the remaining cards are ten-valued. Off the top of a 6–8 deck shoe, ten density is about 30.8%, giving a house edge of about 7.5%. Card counters take it at roughly Hi-Lo true count +3 or higher; everyone else should decline.
Example: At the table: you bet $20 and the dealer shows an ace. Insurance costs $10. If the dealer has blackjack you net $0 on the hand, but over time each $10 insurance bet loses about $0.75.
L
Lightning Blackjack (Evolution Lightning Blackjack, Lightning BJ)
Online, Live Streams & Game Variants
A live-dealer variant in which you pay a Lightning Fee equal to your main bet each round. That fee funds random multipliers (2x–25x) tied to final totals of 17–21, which apply to winning hands in the next round. The fee lowers base EV, so optimal strategy shifts toward more aggressive doubling and splitting. Published RTP sits around 99.5% only with that adjusted strategy.
Example: At the table: you bet $10 and pay a $10 fee, so you risk $20 per round. Next round you stand on 20 with an 8x multiplier active on 20 and win. The win pays $80 instead of $10.
Live Dealer Blackjack (Live Blackjack, Live Casino Blackjack, Streamed Blackjack)
Online, Live Streams & Game Variants
Blackjack streamed from a studio with a human dealer and physical cards, usually from an 8-deck shoe. You submit decisions through software within a timer. Most tables cut the shoe near 50%, which gives poor penetration, and run at roughly 50–60 rounds per hour. Rules vary by table, so check S17 vs H17, the blackjack payout (3:2 vs 6:5) and any doubling restrictions before you sit.
Example: At the table: At $25 per round, 55 rounds per hour and a 0.5% house edge, your expected loss is about $6.90 per hour. The same $25 stake on an RNG table at 500 hands per hour and 0.4% costs about $50 per hour.
Lucky Ladies (Lucky Ladies Side Bet, Queen of Hearts Bet)
Side Bets, Bankroll & Mathematical Expectation
A side bet that pays when your first two cards total 20. A typical paytable is: any 20 4:1, suited 20 10:1, matched 20 25:1, Q♥ pair 200:1, Q♥ pair with dealer blackjack 1000:1. House edge commonly runs 13–25%, among the worst bets in the casino.
Example: At the table: you bet $5 per hand for 200 hands, $1,000 in total action. At a ~17% edge you expect to lose about $170 on the side bet alone, versus roughly $5 on the same action in the main game.
M
Multi-Card 16 (Three-Card 16, Composition-Dependent 16)
Player Actions & Hand Totals
A hard 16 made of three or more cards, such as 4-5-7. In shoe games, composition-dependent strategy stands on a multi-card 16 vs a dealer 10 but hits a two-card 16 such as 10-6 or 9-7. The small cards already in your hand leave the remaining shoe slightly richer in tens, which raises your bust risk when hitting. The EV difference is under 1% of the bet, but it costs nothing to apply. Surrender is not available once you have taken a third card.
Example: At the table: You start with 7-5 vs a dealer 10, hit, and draw a 4, making a three-card 16. Stand. If you had been dealt 10-6 vs 10 with no surrender option, you would hit.
N
Natural (Blackjack, BJ, Snapper)
Player Actions & Hand Totals
A two-card 21: an ace plus a ten-value card as your first two cards. It occurs on about 4.75% of hands in a 6-deck game. It pays 3:2 (or 6:5) and pushes against a dealer natural. A+10 after a split is just 21, not a natural.
Example: At the table: $10 bet and you are dealt A-J. If the dealer has no blackjack, you are paid $15 at 3:2 right away. Expect one natural about every 21 hands.
P
Peek (Dealer Peek, Hole Card Check, Peeking)
Table Selection & Felt Rules
The US-style procedure in which the dealer checks the hole card for blackjack before players act, whenever the upcard is an ace or a ten-value card. If the dealer has a natural, the hand ends and you lose only your original bet, never doubles or splits. US basic strategy charts assume peek.
Example: At the table: the dealer shows a 10, slides the hole card over the peek reader and has no blackjack. You can now double 11 vs 10 knowing the dealer cannot have a two-card 21.
Penetration (Pen, Deck Penetration, Deck Pen)
Table Selection & Felt Rules
The percentage of cards dealt before the reshuffle. It is the most important game variable for counters, because deeper penetration produces more high true counts. In a 6-deck shoe, games below about 70% are rarely worth counting; 80% or more is strong.
Example: At the table: a cut card placed 1 deck from the back of a 6-deck shoe means 5/6, or 83% penetration. Placed 2 decks from the back, it means 67%, and the same bet spread earns far less per hour.
Perfect Pairs (Perfect Pair, Pairs Side Bet)
Side Bets, Bankroll & Mathematical Expectation
A side bet that pays if your first two cards form a pair. The standard paytable is: perfect pair (same suit) 25:1, colored pair (same color, different suit) 12:1, mixed pair 6:1. With 8 decks the house edge is about 4.1%, and a pair of any kind lands only about 7–8% of the time.
Example: At the table: you bet $10 and get K♥ K♦, a colored pair that pays $120. The other ~92% of rounds, the $10 is simply gone.
Power Blackjack (Evolution Power Blackjack, Power Double, Power Split)
Online, Live Streams & Game Variants
A live variant dealt from 8 decks with all 9s and 10s removed; J, Q and K remain. To compensate, you may Power Double (raise to 2x, 3x or 4x your bet on any two cards) and Power Split up to four hands. Removing the 9s and 10s hurts the player, and the extra doubling options only partly offset it. RTP is about 98.8% with optimal strategy.
Example: At the table: you hold 11 vs dealer 6 with a $10 bet. A Power Double to 4x puts $40 in action, which is correct because no 9s or 10s can bust the dealer's strong draw against you.
Pre-Decision (Pre-Select, Advance Action)
Online, Live Streams & Game Variants
A live online feature that lets you queue your action (hit, stand, double, split) before your seat's turn, based on your cards and the dealer upcard. It speeds up the game and prevents timer losses. Because the decision depends only on information already visible, pre-deciding costs no EV as long as you follow basic strategy.
Example: At the table: in seat 5 you hold A-7 vs dealer 6 while seats 1–4 are acting. You pre-select Double, and it executes instantly when your turn arrives.
Provably Fair (Provably Fair Gaming, Hash-Verified RNG, Verifiable Fairness)
Online, Live Streams & Game Variants
A cryptographic commit-reveal scheme used mostly by crypto casinos. Before play, the casino publishes a hash, typically SHA-256, of a secret server seed. That seed is combined with your client seed and an incrementing nonce to generate each shuffle. After you rotate seeds, the casino reveals the server seed, so you can recompute every deck order and confirm nothing was changed after your bet. It proves outcome integrity, not good rules: a provably fair 6:5 game still carries about 1.4% extra house edge.
Example: At the table: Before hand #57 you note the hash 9f2c…. After rotating seeds, you SHA-256 the revealed server seed and confirm it matches 9f2c…. You then run the server seed, your client seed and nonce 57 through the site's open-source verifier to reproduce the exact card order that was dealt.
Push (Tie, Standoff)
Player Actions & Hand Totals
A tie between the player's and dealer's totals. The bet is returned, with no win or loss. About 8.5% of hands end in a push. A player bust never pushes: it loses even if the dealer also busts.
Example: At the table: you stand on 19 and the dealer draws to 19. Your $25 stays in place for the next round, or you can pull it back.
R
Rakeback (Cashback, Loss Rebate, Comp Return)
Side Bets, Bankroll & Mathematical Expectation
A percentage of your activity returned by the casino. It is calculated either on theoretical loss (turnover × house edge) or on actual net losses (cashback). Rakeback lowers your effective house edge. Rebates on actual losses can even turn break-even play slightly positive, since losing sessions are partly refunded while winning sessions are kept in full.
Example: At the table: you wager $20,000 at a 0.5% edge, a theoretical loss of $100. A 20% rakeback on theo returns $20, cutting your effective edge to 0.4%.
Resplit (Re-split, Resplitting, Resplit Pairs)
Player Actions & Hand Totals
To split again when a split hand receives another card of the same rank. Most casinos allow resplitting non-ace pairs up to 4 hands in total. Resplitting aces (RSA) is a separate and less common rule.
Example: At the table: you split 8-8 vs dealer 9 and the first hand catches another 8. Add a third $25 bet and resplit. If a fourth 8 arrives, you can usually go to four hands ($100 in total).
Risk of Ruin (RoR, Ruin Probability)
Side Bets, Bankroll & Mathematical Expectation
The probability of losing an entire bankroll before reaching a goal or playing indefinitely. For positive-EV play a standard approximation is RoR ≈ e^(−2·μ·B/σ²), where μ is the edge per hand, σ² the variance per hand and B the bankroll in units. For negative-EV play, RoR over unlimited play is 100%.
Example: At the table: a counter averages a 1% edge (μ = 0.01) with σ² = 1.32 and a 200-unit bankroll. RoR ≈ e^(−3.03) ≈ 4.8%. Halving the bankroll to 100 units raises it to about 22%.
RNG Blackjack (Digital Blackjack, Software Blackjack, Virtual Blackjack)
Online, Live Streams & Game Variants
Computer-dealt blackjack in which the card order comes from a certified random number generator, tested by labs such as GLI, iTech Labs or eCOGRA. Most versions reshuffle every round, so card counting has zero value. The house edge is fixed by the rules: about 0.4% for 6 decks, S17, DAS and 3:2, plus about 1.4% if blackjack pays 6:5. Speed is the main risk, because 300–600 hands per hour multiplies your expected loss.
Example: At the table: You bet $10 per hand at a 0.4% house edge. A live dealer game at 60 hands per hour costs about $2.40 per hour in expectation. An RNG game at 500 hands per hour costs about $20 per hour on identical rules.
RSA (Resplit Aces) (Resplit Aces, RSA, Re-splitting Aces)
Table Selection & Felt Rules
A rule allowing you to split again when a split ace receives another ace. It is worth about 0.08% to the player in 6-deck games. Split aces still normally receive only one card each.
Example: At the table: you split A-A for $50 total and the first ace draws another ace. With RSA you add $25 and play three aces. Without RSA you are stuck with a soft 12 and no further action.
S
S17 (Dealer Stands on Soft 17) (Stands on Soft 17, S17, Dealer Stands on All 17s)
Table Selection & Felt Rules
A rule requiring the dealer to stand on every 17, including soft 17 (A-6). It is worth about 0.2% to the player compared with H17. It also changes some strategy plays: in 6-deck S17, 11 vs ace is a hit, while under H17 it is a double.
Example: At the table: the dealer shows A-6. Under S17 the dealer stops at 17 and your 18 wins. Look for 'Dealer must stand on all 17s' printed on the felt.
Shoe (Dealing Shoe, Multi-Deck Shoe, Sabot)
Table Selection & Felt Rules
A box holding multiple decks that are dealt one card at a time, usually 6 decks (312 cards) or 8 decks (416 cards). More decks raise the house edge slightly (about 0.02-0.03% going from 6 to 8) and dilute the count. Counters convert the running count to a true count by dividing it by the number of decks remaining.
Example: At the table: a running count of +9 with about 3 decks left in a 6-deck shoe gives a true count of +3, roughly a 1% player edge with Hi-Lo.
Shuffler Window (Shuffle Window, Penetration Window, Shoe Window)
Online, Live Streams & Game Variants
The portion of the shoe dealt between shuffles; it is the only stretch in which card removal can create exploitable counts. Live online 8-deck games commonly shuffle at about 50% penetration, which makes high true counts rare. A continuous shuffling machine (CSM), or RNG blackjack that reshuffles every hand, shrinks the window to zero and makes counting worthless.
Example: At the table: in an 8-deck live game the cut card sits at 4 decks. You see about 4 decks per shoe, and a true count of +3 or higher appears on only a small fraction of hands. On a CSM table, the same count never develops.
Soft Hand (Soft Total, Soft Hand)
Player Actions & Hand Totals
Any hand containing an ace that is counted as 11 without the total going over 21. A soft hand cannot bust on the next card, because the ace can revert to 1. Soft 18 (A-7) is the most misplayed soft hand: in 6-deck S17 it hits vs 9, 10 and ace and doubles vs 3-6.
Example: At the table: A-7 vs dealer 10. Standing on 18 feels safe but loses more, so hit. If you draw a 6, A-7-6 becomes hard 14 (the ace now counts as 1), and you hit again.
Spanish 21 (Spanish Blackjack, Pontoon (Spanish))
Online, Live Streams & Game Variants
Blackjack dealt from 48-card decks with the four pip 10s removed; face cards remain. Removing them costs the player about 2%. Liberal rules buy most of that back: a player 21 always wins, late surrender, doubling on any number of cards, double-down rescue, and 21 bonuses (5 cards 3:2, 6 cards 2:1, 7+ cards 3:1, plus 6-7-8 and 7-7-7 bonuses). House edge is about 0.4% with S17 and redoubling allowed, and about 0.8% with H17. It requires its own strategy chart.
Example: At the table: you hit 4-3-2-5-7 to make a 5-card 21 on a $20 bet. It pays $30 at 3:2, and you win even if the dealer also makes 21.
Split (Splitting Pairs, Pair Split, SPL)
Player Actions & Hand Totals
To separate two cards of equal rank into two hands, placing a bet equal to the original on the second hand. Each hand is played independently. Under US peek rules, always split A-A and 8-8, and never split 10-10 or 5-5. Split aces usually get one card each, and A+10 after a split counts as 21, not blackjack.
Example: At the table: $25 on 8-8 vs dealer 10. Playing it as hard 16 loses about $13.40 on average, while two hands starting with 8 lose about $12 combined. Splitting is the least-bad option.
Stand (Stay, Stand Pat, Stick)
Player Actions & Hand Totals
To take no more cards and keep your total. It is correct on hard 17 and above, on hard 13-16 vs dealer 2-6, on hard 12 vs 4-6, and on soft 19 and above, except for a few soft doubles under some rules.
Example: At the table: hard 13 vs dealer 6. The dealer busts about 42% of the time from a 6, so stand and let the dealer draw. Wave your hand flat over your cards.
Stiff Hand (Stiff, Stiff Hand, Breaking Hand)
Player Actions & Hand Totals
A hard total of 12 through 16: high enough to risk busting with one hit, but too low to win often by standing. Approximate one-card bust probabilities: 12 = 31%, 13 = 38%, 14 = 46%, 15 = 54%, 16 = 62%.
Example: At the table: with hard 15 vs dealer 5, stand and let the dealer, who busts about 43% of the time from a 5, take the risk. With hard 15 vs dealer 10, surrender if allowed; otherwise hit.
Stop-Loss (Loss Limit, Session Loss Cap)
Side Bets, Bankroll & Mathematical Expectation
A pre-set loss level at which you end the session. It does not change EV per hand, since the edge is identical on every hand. It does cap single-session damage and blocks tilt-driven decisions. Set it before play, typically at 30–50% of the session bankroll.
Example: At the table: you start with $500 and a $200 stop-loss. After a bad run you are at $300, so you leave, instead of chasing with $50 bets you would normally never make.
Surrender (Late Surrender, LS, Early Surrender, ES)
Table Selection & Felt Rules
The option to give up half your bet and end the hand before taking any other action. Late surrender, offered after the dealer peeks, is worth about 0.07-0.09%. Early surrender, offered before the peek, is worth roughly 0.6%. Surrendering is mathematically correct whenever your expected loss is greater than 50% of the bet.
Example: At the table: hard 16 vs dealer 10 with a $50 bet. Playing the hand out loses about $27 on average, while surrender costs a fixed $25. Say 'surrender' or draw a horizontal line behind your bet.
T
Table Maximum (Max Bet, Table Max, Table Limit)
Table Selection & Felt Rules
The largest wager allowed per hand. It caps your bet spread and breaks Martingale-style progressions. Starting from $10, seven straight losses require a $1,280 bet, which is beyond a typical $1,000 limit.
Example: At the table: at a $25-$500 game, your widest possible spread is 1-20. At a $25-$200 table, a 1-12 counting spread ($25-$300) is impossible, so either play 1-8 or find another table.
Table Minimum (Min Bet, Table Min, Minimum Bet)
Table Selection & Felt Rules
The smallest wager allowed per hand. It sets your base bet, your bankroll needs and your hourly expected loss. Blackjack's standard deviation is about 1.15 bets per hand, so at a $25 minimum a 100-hand session swings about ±$290 (one standard deviation).
Example: At the table: a $15 minimum with a 1-8 spread needs a $120 maximum bet. A counter with a $12,000 bankroll then holds 100 max bets, a common conservative benchmark.
Third Base (Anchor, Anchor Seat, Last Seat)
Player Actions & Hand Totals
The seat immediately to the dealer's right, acting last before the dealer. Counters prefer it because every other player's cards are exposed before their decision, which makes index plays more accurate. The belief that third base 'takes the dealer's bust card' is false: the order of unseen cards is random, so other players' decisions do not change your long-run EV.
Example: At the table: Hi-Lo running count is −1 before the round, with 3 decks left. You hold 10-6 vs a dealer 10, so RC is −2 and TC about −0.7: hit. From third base you also see six low cards and two tens in other hands, so RC becomes +2 and TC about +0.7: stand. The Illustrious 18 index is stand on 16 vs 10 at TC 0 or higher.
Tilt (On Tilt, Steaming, Chasing Losses)
Side Bets, Bankroll & Mathematical Expectation
An emotional state, usually after losses or bad beats, that causes deviations from basic strategy and planned bet sizing. Typical tilt behavior includes chasing with oversized bets, skipping correct doubles out of fear, and adding side bets. Its cost compounds: strategy errors raise the effective house edge, and oversized bets multiply variance and risk of ruin.
Example: At the table: after losing 6 hands in a row at $25, you jump to $100 bets and stand on 12 vs 2 out of fear. Your hourly expected loss rises from about $12 to over $60.
U
Unit (Betting Unit, Base Bet)
Side Bets, Bankroll & Mathematical Expectation
Your standard base bet, used as the measuring stick for bankroll, bet spreads and results. Recreational players typically size a unit at 1–2% of their session bankroll. Counters size it from total bankroll and acceptable risk of ruin, often 1/100 to 1/200 of bankroll. Expressing results in units removes stake size from analysis.
Example: At the table: with a $1,000 session bankroll and a 2% unit, you bet $20. A 1–8 spread means betting $20–$160, and finishing up $100 is reported as +5 units.
Upcard (Dealer Upcard, Face-Up Card, Door Card)
Player Actions & Hand Totals
The dealer's face-up card, visible before any player decision. It is the most important input in basic strategy. Dealer bust probability is about 42% with a 5 or 6 showing, about 23% with a 10 (after the peek) and about 17% with an Ace (S17, after the peek).
Example: At the table: You hold hard 12. Against a 4 you stand, because the dealer busts about 40% of the time. Against a 7 you hit, because the dealer busts only about 26% of the time and usually finishes on 17 or higher.
V
Variance (Standard Deviation, Swings, Volatility)
Side Bets, Bankroll & Mathematical Expectation
The statistical spread of results around expected value. In blackjack the standard deviation is about 1.15 units per hand (variance ≈ 1.32), so short-term swings dwarf the house edge. Standard deviation grows with the square root of the number of hands, while EV grows linearly. Side bets and aggressive doubling and splitting variants increase variance.
Example: At the table: over 100 hands at $10, EV at a 0.5% edge is -$5, but one standard deviation is 1.15 × $10 × √100 = $115. Finishing anywhere from -$120 to +$110 is routine.
W
Wagering Requirement (Playthrough, Rollover, WR)
Side Bets, Bankroll & Mathematical Expectation
The total turnover required before bonus funds become withdrawable, expressed as a multiple of the bonus (sometimes bonus plus deposit). Expected cost = required turnover × house edge. Compare that cost to the bonus value before accepting. Low blackjack contribution rates often push the cost above the bonus itself.
Example: At the table: a $100 bonus carries a 35x requirement, so $3,500 in turnover. If blackjack contributes 10%, you must wager $35,000 on blackjack. At a 0.5% edge that costs about $175, so the bonus is worth -$75.
Win Goal (Win Limit, Profit Target)
Side Bets, Bankroll & Mathematical Expectation
A pre-set profit level at which you end the session. Like a stop-loss, it does not alter EV, because future hands carry the same edge whether you are ahead or behind. Its value is behavioral: it locks in results and limits further exposure to a negative edge. For negative-EV players, less total action means less expected loss.
Example: At the table: you set a +$150 win goal on a $500 session bankroll. You reach +$155 after 90 hands and cash out, avoiding the roughly $12 extra expected loss from another 250 hands at $10.

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