Every blackjack decision has a mathematically best answer, worked out by simulating millions of hands. Together those answers are called basic strategy. It doesn't guarantee a win, and the house keeps an edge, but under common rules it cuts that edge to roughly 0.5%. Playing on hunches usually costs considerably more.
The rules in brief
You and the dealer each aim for a total closer to 21 than the other, without going over. Cards 2 to 10 count at face value, picture cards count as 10, and an ace counts as 1 or 11. A hand with an ace counted as 11 is soft: ace + 6 is soft 17, and it can't bust on the next card. An ace with a ten-value card as your first two cards is a blackjack, which normally pays 3 to 2.
The dealer has no choices: they must draw to 16 and stand on 17. Tables state whether the dealer stands or hits on a soft 17. Your options are to hit (take a card), stand, double (double your stake for exactly one more card), split a pair into two hands, and on some tables surrender half your stake to end the hand.
Hard totals
This strategy is for six- or eight-deck games where the dealer stands on soft 17 and doubling after a split is allowed, which are common rules online. “Dealer 2 to 6” means the dealer's face-up card.
| Your hand | What to do |
|---|---|
| 8 or less | Hit |
| 9 | Double against dealer 3 to 6; otherwise hit |
| 10 | Double against dealer 2 to 9; otherwise hit |
| 11 | Double against dealer 2 to 10; hit against an ace |
| 12 | Stand against dealer 4 to 6; otherwise hit |
| 13 to 16 | Stand against dealer 2 to 6; otherwise hit |
| 17 or more | Stand |
If doubling isn't allowed, for example after taking a third card, hit instead.
Soft totals
| Your hand | What to do |
|---|---|
| Ace + 2 or ace + 3 | Double against dealer 5 or 6; otherwise hit |
| Ace + 4 or ace + 5 | Double against dealer 4 to 6; otherwise hit |
| Ace + 6 | Double against dealer 3 to 6; otherwise hit |
| Ace + 7 | Double against dealer 3 to 6; stand against 2, 7 or 8; hit against 9, 10 or an ace |
| Ace + 8 or ace + 9 | Stand |
If you can't double, hit, except with ace + 7, where you stand.
Pairs
| Your pair | What to do |
|---|---|
| Aces | Always split |
| Tens and picture cards | Never split; stand on 20 |
| 9s | Split against dealer 2 to 6, 8 or 9; stand against 7, 10 or an ace |
| 8s | Always split |
| 7s | Split against dealer 2 to 7; otherwise hit |
| 6s | Split against dealer 2 to 6; otherwise hit |
| 5s | Never split; play as a hard 10 |
| 4s | Split against dealer 5 or 6; otherwise hit |
| 2s or 3s | Split against dealer 2 to 7; otherwise hit |
If late surrender is offered, surrender a hard 16 against a dealer 9, 10 or ace, and a hard 15 against a 10. Otherwise, follow the tables above.
Insurance and side bets
When the dealer shows an ace, you may be offered insurance: a side bet of half your stake that pays 2 to 1 if the dealer has blackjack. In an eight-deck shoe only about 31% of the remaining cards are worth 10, so insurance wins too rarely for a 2-to-1 payout to be fair. Its house edge is around 7%, many times that of the main game. Basic strategy is to decline it, and that includes “even money” on your own blackjack, which is the same bet in a different form.
Side bets such as pairs or poker-hand bets pay large multiples but carry a much higher house edge than the main hand.
Table rules that change the edge
| Rule | Approximate effect |
|---|---|
| Blackjack pays 6 to 5 instead of 3 to 2 | Adds about 1.4 percentage points |
| Dealer hits soft 17 | Adds about 0.2 points |
| No doubling after a split | Adds about 0.14 points |
| Late surrender allowed | Removes about 0.08 points |
Approximate effects in six- and eight-deck games. The payout on blackjack matters most.
Check the rules panel before you sit down. A 6-to-5 table costs nearly four times as much as a standard 3-to-2 table on the same strategy.
Why card counting rarely matters online
Digital blackjack shuffles every hand. Live tables deal from a shoe, but they usually reshuffle long before it runs out, which removes most of what a counter would need. For online play, basic strategy and choosing good rules are what make the difference.
“Basic strategy won't beat the house. It stops you paying more than you have to.”
Even perfect play loses over time, because the house keeps an edge. Set a session budget and stake before you start: see setting limits that work.