Blackjack Rules and Terms

The goal is not twenty-one

Start with the most common misunderstanding. The object of blackjack is not to make 21 but to beat the dealer. Go over 21 and you lose immediately, whatever the dealer is holding. Stand on 12 and you win with it if the dealer busts.

This distinction matters because it explains every cell in the chart that makes you think "why would I stop here?" Standing on hard 16 against a dealer 6 is not a claim that 16 is a good hand. It is a bet that the dealer collapses more often than another card saves you.

Card values

2 – 10: Face value.
J · Q · K: All count as ten. Suits mean nothing in blackjack.
A (ace): Counts as one or eleven, whichever helps you. This is automatic; you never choose.

A hand where the ace can be counted as eleven without busting is a soft hand. An ace and a seven is soft 18. Draw a six and eleven would make 24, so the ace drops to one and the hand becomes hard 14. The crucial property is that a soft hand cannot bust on the next card. That is why soft hands play so aggressively in the chart.

How a hand proceeds

You place your bet.
You receive two cards face up. The dealer receives one face up (the upcard) and one face down (the hole card).
If the dealer's upcard is an ace or a ten-value card, the dealer first checks for blackjack. If the dealer has it, the hand ends there.
Players act in turn, continuing until they stand or bust.
When every player has finished, the dealer turns over the hole card and draws according to fixed rules.
Hands are compared and bets settled.

The five plays available to you

Every answer the calculator gives is one of these five.

H Hit: Take one more card. You may repeat as long as you stay at or under 21.
S Stand: Stop with your current hand. Your turn ends.
D Double down: Double your bet in exchange for exactly one more card, after which you must stop. Only available on your first two cards. It is how you put more money down when the odds favour you.
P Split: Separate two cards of equal value into two independent hands, adding a second bet equal to the first. Usually allowed up to three times, for four hands.
R Surrender: Forfeit half your bet and withdraw from the hand. Only on the first two cards, and many tables do not offer it at all. It exists to halve your loss on hands that are too far behind to defend.

Double and surrender are first-two-cards only

Every strategy chart is built on the assumption that you hold exactly two cards. If you have hit even once, a D or R printed in the chart describes an option that no longer exists. You need the fallback play instead — which the calculator works out for you automatically.

The dealer has no choices

The dealer does not make decisions. On 16 or less the dealer must draw; on 17 or more the dealer must stop. The procedure is identical even when every player has already busted.

Exactly one point varies between tables: soft 17.

S17: The dealer stands on soft 17 (for example ace plus six). Better for you.
H17: The dealer draws on soft 17. This raises the house edge by roughly 0.2 percentage points.

Most tables print this rule on the felt itself. In the calculator, the inscription between the dealer's side and yours changes to match whichever setting is active.

Payouts

Ordinary win: Pays even money — one times your bet.
Blackjack: An ace plus a ten-value card on your first two cards pays one and a half times your bet (3:2). Twenty-one built from three or more cards is not a blackjack.
Push: A tie with the dealer. Your bet is returned.
Bust: Over 21 loses at once, regardless of the dealer's hand.

Avoid tables that pay 6:5 on blackjack

Tables paying 6:5 instead of 3:2 for blackjack have become common. That single line of the rules adds roughly 1.4 percentage points to the house edge — more than enough to wipe out every other favourable rule combined. Check the printed payout before you sit down.

Never take insurance

When the dealer shows an ace you will be offered insurance: an extra side bet of half your stake that pays 2:1 if the dealer has blackjack.

For a 2:1 payout to be profitable, the dealer's hole card would need to be a ten-value card more than one third of the time. In a full deck, 16 of 52 cards are ten-value — about 30.8%. Unless you are counting and know the remaining cards are rich in tens, insurance always loses money. "Even money" is the same bet under a friendlier name.

How much each rule moves the house edge

The figures below are approximate changes from a six-deck, S17, DAS-allowed, blackjack-pays-3:2 baseline with a house edge of roughly 0.4–0.5%. Negative numbers favour the player.

Approximate effect of each rule
Rule	Change	Note
Blackjack pays 6:5	+1.4 pp	The most damaging single rule
Dealer hits soft 17	+0.2 pp	H17 instead of S17
One deck → eight decks	+0.5 pp	More decks is worse for you
No double after split	+0.14 pp	DAS not offered
No dealer hole card	+0.1 pp	European style; extra bets are lost
Late surrender offered	−0.08 pp	Only if you actually use it correctly
Resplitting aces allowed	−0.08 pp	An uncommon rule

Exact values shift a little depending on the rest of the rule set. What matters is not the individual numbers but the order: the payout dominates everything, soft 17 and deck count come next, and rules like surrender or resplitting aces move the needle comparatively little.

Glossary

Upcard: The dealer's face-up card. Half of every decision rests on it.
Hole card: The dealer's face-down card, hidden until the players have finished.
Hard hand: A hand with no ace, or one where the ace must count as one.
Soft hand: A hand where the ace can count as eleven without busting. It cannot bust on the next card.
Natural: Twenty-one on the first two cards. Another word for blackjack.
Push: A tie with the dealer.
Shoe: The box holding several shuffled decks, usually four to eight.
Penetration: How far into the shoe play continues before a reshuffle. Only meaningful to card counters.
DAS: Double After Split — the rule permitting a double down on a hand created by splitting.
House edge: The share of total money wagered that the casino keeps on average over the long run.
Expected value (EV): The average result of a situation repeated indefinitely. The strategy chart is simply the collection of plays with the highest EV.

Next Why the Chart Works Dealer bust probabilities explain almost every cell in the chart. Tool Strategy Calculator Enter the hand you are holding and check it now.