When to Split 8s and Aces

Of the ten pair hands in basic strategy, eight have answers that change depending on what the dealer shows. Two do not. A pair of 8s and a pair of aces are split against every dealer upcard, from a 2 through an ace, without exception.

That is unusual enough to be worth understanding rather than memorising, because the case that feels most wrong, splitting 8s against a dealer 10, is the one players get wrong most often.

Aces: the obvious one

A pair of aces played as one hand is a soft 12. That is close to the worst starting total in the game: you cannot bust, but you also cannot get to a competitive number without drawing several times.

Split them and each ace becomes the start of a hand where any ten-value card makes 21. Roughly three cards in thirteen do that. Two live hands with that upside beat one hand stuck at 12 against any upcard, which is why the answer never changes.

8s: the one that feels wrong

A pair of 8s is a hard 16, statistically the worst hand in blackjack. You bust more often than not if you hit, and standing on 16 against a strong upcard loses most of the time.

Splitting does not turn 16 into a good hand. It turns one terrible hand into two mediocre ones, each starting at 8, which is a legitimate base. Against a dealer 10 you will still lose money on average. You will lose less than you would playing 16 as a single hand, and that is the whole argument.

Losing less is the correct goal

This is the part that trips people up. Basic strategy does not always hand you a winning play. On some hands every option loses money and the correct move is simply the one that loses least.

Splitting 8s against a 9, 10 or ace is exactly that situation. Players who refuse to split there because "you are throwing good money after bad" are choosing a worse expected result to avoid the feeling of doubling their exposure on a bad hand.

What about surrender

If your table offers late surrender, 16 against a 9, 10 or ace is a surrender hand, and a pair of 8s is a 16. Where surrender is available, surrendering the 8s against those three upcards is slightly better than splitting.

Most tables do not offer it, and the calculator on this site assumes it is unavailable. Without surrender, split.

Doubling after the split

Both of these plays get better when the house allows doubling after a split, which most do. Split 8s and catch a 3 on one of them for an 11, and you want to double that hand.

The strategy this site uses assumes doubling after split is permitted. If your table forbids it, splitting 8s against a 10 gets marginally worse, though it remains the correct play.

The one rule that never changes

Never split 10s, and never split 5s. A pair of 10s is a 20, which wins on its own more often than two hands starting at 10 will. A pair of 5s is a hard 10, which you should double, not split.

Those two, along with always splitting 8s and aces, are the four pair decisions worth knowing cold. The rest you can look up.

Enter the hand into the calculator to see the recommendation for any pair against any upcard, or browse the full pair splitting chart.

A note on risk. Basic strategy reduces the house edge to roughly half a percent. It does not remove it. Nothing here is gambling advice or a prediction of results. If gambling has stopped being entertainment, the National Problem Gambling Helpline is 1-800-522-4700, or ncpgambling.org.