Rules & variants

It means the dealer keeps drawing when their hand is a 17 that includes an ace counted as eleven, for example ace–six, and only stops on a hard 17 or any total of 18 or more. Casinos abbreviate this rule to H17. The alternative, S17, has the dealer stand on every 17. Hitting soft 17 helps the house: the dealer can improve the hand more often than it busts, which adds roughly 0.2 percentage points to the house edge compared with the same game under S17. Read more →

Double after split, abbreviated DAS, means that once you have split a pair you may double down on either of the resulting hands if the first card drawn makes a good doubling total. Split a pair of fours against a 6, draw a five on one hand for a nine, and DAS lets you double on that nine. The rule favours the player by roughly 0.1 to 0.15 percentage points and changes a few strategy decisions: with DAS you split 2s and 3s against a 2 or 3, 4s against a 5 or 6, and 6s against a 2. Read more →

The ratio is what a winning natural pays. At 3:2 a £10 bet on a blackjack wins £15; at 6:5 the same bet wins only £12. You are dealt a natural about 4.75% of the time in a six-deck game, so losing £3 of profit per £10 on each one costs about 1.4 percentage points of return over the long run. That is more than every other common rule variation combined, which is why experienced players avoid 6:5 tables even when the minimum bet is lower. Read more →

Anything from one to eight standard 52-card decks, with no jokers. Most casino tables today deal six or eight decks from a shoe; single- and double-deck games are usually dealt by hand. Fewer decks are better for the player when every other rule is equal, because naturals and good doubles come slightly more often, but casinos frequently pair single-deck games with the 6:5 payout, which more than wipes out the deck advantage. Check the payout before the deck count. Read more →

In a no-hole-card game the dealer takes only one card at the start and draws the second after all players have finished. Because there is no hole card, the dealer cannot check for blackjack before you act, so you may double or split and then lose to a dealer natural. Under the strict European rule (ENHC) you lose every bet on the table; under "original bets only" (OBO) you lose only your initial stake. Strategy adjusts: against a dealer ace or 10 you double and split less often. Read more →

When the dealer's upcard is an ace or a ten-value card, a US-style game has the dealer check the face-down hole card for a natural before any player acts, usually with a small mirror or electronic reader so nobody else sees it. If there is a blackjack, the round ends and only insurance bets and player naturals are settled. If there is not, play continues and you can double or split knowing you cannot lose those extra bets to a dealer natural. The site's chart assumes this peek rule. Read more →

Slightly. The core chart for four to eight decks is identical, which is why this site uses one six-deck chart. Single- and double-deck games have a handful of extra doubles because removing a few cards changes the composition more: for example, in single deck you double hard 8 against a 5 or 6 and hard 11 against an ace. The dealer's soft-17 rule and whether you may double after splitting change more decisions than the deck count does. Always state which rules a chart assumes. Read more →

About 1.4% of every bet. You are dealt a natural roughly 4.75% of the time in a six-deck game, and 6:5 pays 1.2 times the bet instead of 1.5, a shortfall of 0.3 bets each time: 0.0475 × 0.3 ≈ 0.014, or 1.4 percentage points, slightly less once naturals that push against a dealer natural are excluded. Published figures put the cost at about 1.39%. That turns a game with a 0.4% edge into one with nearly 1.8%, more than quadrupling what the casino expects to win from you. Read more →