Should you always split aces?

Should you always split aces in blackjack?

In ordinary blackjack, splitting aces is one of the two pairs that basic strategy splits every time (the other is eights). Wizard of Odds' four-to-eight-deck strategy (opens in a new tab), for games where the dealer stands on soft 17, gives the same instruction for every dealer up card from 2 to ace. That makes it one of the simplest rules on any basic strategy chart.

The 'always' comes with a small footnote. Some game rules change the maths, mainly the European no-hole-card procedure and variants with unusual split rules. We cover those below. For a standard hole-card game, though, you never need to think twice.

Why splitting aces beats playing soft 12

Two aces together count as 2 or 12. As a single hand that is a soft 12, which can't bust on the next card but is a long way from a winning total. You would need to draw several cards and hope to land between 17 and 21.

Split them and you have two hands, each starting with an ace worth 11. Any ten-value card makes 21 straight away, and any card from 6 upwards gives at least soft 17. You put a second bet equal to the first on the table, but each of those bets now starts from the strongest single card in the deck. The ace's flexibility, counting as 1 or 11, is explained on our soft hands page.

Split aces odds: what one card gives you

Most tables give each split ace just one more card. Using a simple infinite-deck approximation, where each of the 13 ranks is equally likely, here is where a split ace ends up:

Add up the first five rows and a split ace finishes on 17 to 21 about 61.5% of the time (8 in 13). Nearly a third of the time it reaches 21. Compare that with soft 12, which needs at least one more card just to reach a standing total and often several. The two split hands are not guaranteed to win, but each starts in a far better spot than the combined pair.

How much splitting aces is worth in pounds

Wizard of Odds' rule-variation table (opens in a new tab) shows that a game where you are not allowed to split aces costs the player 0.18%, measured against an eight-deck game with the dealer standing on soft 17. That is spread over every hand you play, yet a pair of aces turns up only rarely:

Dividing the 0.18% by the eight-deck chance of a pair of aces (0.57%) gives about 0.31. In other words, each time you split aces correctly you are, on average, about 31% of your starting bet better off than if the rule forced you to play soft 12. On a £10 hand that is roughly £3.10 of average value from one decision. Over 1,000 hands at £10 the rule is worth about £1.80 in total, because the situation comes up so seldom.

Split aces rules that vary by blackjack table

The decision to split is fixed, but what happens next depends on the table. Check these in the game's help screen.

• One card each. Split aces normally receive exactly one more card. You can't hit again, even on 13.
• 21 is not blackjack. At most tables an ace and a ten on a split hand is a plain 21 paid at even money, not 3 to 2.
• Re-splitting aces. If you draw another ace, some games let you split again, a rule worth about +0.08% to the player.
• No re-splitting at all. Banning re-splits of any pair costs about 0.10%.
• Doubling after splitting. Many tables allow it on other pairs, but split aces usually get only one card, so it rarely applies to them.

Our guide to when to split covers the other pairs, and the re-split glossary entry explains how extra hands are formed.

When the 'always split aces' rule changes

No-hole-card (European) tables

In many European-style games the dealer takes a second card only after all players have acted. Under that procedure, if the dealer makes blackjack you lose the full amount bet, including the second bet you added to split. That makes splitting against a dealer ten or ace more costly, and doubling or splitting against those cards is rarely correct in no-hole-card games. That is why a separate European strategy chart exists. Against a dealer ten or ace, follow the chart for that exact game rather than the standard rule; against 2 to 9, the split stands.

Free Bet Blackjack

In Evolution's Free Bet Blackjack, you get a free split on all pairs except tens, so splitting aces needs no extra stake from you. The trade-off is that a dealer 22 pushes your bet. Splitting aces is still the natural choice there.

Other variants

Games such as Power Blackjack remove 9s and 10s from the shoe, and Pontoon versions use their own split-ace rules. The basic idea holds, but always read the help screen before assuming standard play.

How to split aces in online and live blackjack

1. Check that your balance covers a second bet equal to your first.
2. When you're dealt two aces, tap the Split button before the decision timer runs out.
3. The game moves one ace to a second box and places a matching bet on it.
4. Each ace receives one card. If you draw another ace and re-splitting is allowed, you'll be offered Split again.
5. Both hands then stand automatically, and the dealer plays out the round.
6. Each hand is settled on its own: one can win while the other loses or pushes.

In live games the decision window is timed, and UK rules require at least five seconds per game cycle for casino games other than slots. If you're new to the controls, a slower table or an RNG version gives you more time. Our live blackjack page explains how live decisions work.

Myths about splitting aces

'Don't split aces against a dealer ace, you'll lose twice.' In a standard peek game the dealer has already checked for blackjack before you act, so a dealer ace that stays in play is not hiding a natural. The split is correct.

'Splitting doubles the house edge.' It doubles the money on the table for that hand, but it lowers your expected loss compared with keeping soft 12. More money at stake on a favourable decision is not the same as a worse game.

'If I split and lose both, I should have kept them.' Individual results tell you nothing about the decision. About 30.8% of the time a split ace still lands on a weak 13 to 16. Judge the play over many hands, as the house edge does. See also common blackjack mistakes.

Where to play blackjack and practise splits

These partner offers are slot promotions and are not designed for blackjack. Table and live games are often excluded from wagering or count for less, so check the terms first. 18+ and terms apply.

• Casumo: new customers who opt in get a 50% bonus up to £100 on a first deposit of £20 or more, to be wagered 10x within 7 days, with a £5 maximum bet while active and game, play and payment restrictions.
• 10bet: new UK customers who choose the casino bonus and deposit within 7 days get a 100% match up to £25, wagered 10x on slots within 3 days, with bonus winnings capped at £1,000 and Skrill and Neteller excluded.
• Coral: new players who deposit and bet £10 or more on slots receive 100 free spins at 10p on selected games, to accept within 48 hours and use within 7 days, with no wagering on winnings; the offer runs 1 October 2026 to 1 February 2027 and excludes some payment methods.

For blackjack, look in each casino's table game lobby and compare split rules in the help screens. Our interactive strategy chart shows the correct play for every pair.

18+. Every casino game has a built-in house edge, so over time you should expect to lose what you stake. Set a budget before you play and stop when it’s gone: safer gambling tools and support. Free, confidential help: National Gambling Helpline 0808 8020 133.