17 octobre 2026
When to Split in Blackjack: Every Pair, Every Dealer Card
When to split in blackjack, pair by pair against every dealer card, and what each wrong split costs in cents per dollar, worked out on our own table rules.
Always split aces and eights. Never split tens or fives. Every other pair depends on the dealer's up card, and the list below tells you which way to go against each one.
The numbers in this guide come from an exact calculation for the rules on our in-house Blackjack: blackjack pays 3 to 2, the dealer stands on all 17s and peeks for blackjack, you can double after splitting, and you can split once. Played perfectly, that game returns 99.43%, and the split decisions are a decent part of how you get there.
Aces and eights: split every time
A pair of eights is 16, the worst total in the game. Against a dealer 10, standing or hitting on 16 loses about 54 cents for every dollar bet over time. Splitting loses about 49 cents per dollar of your original bet. That's the honest version of the advice: splitting eights against a 10 doesn't win, it loses less, and over a lot of hands the gap adds up to real money.
Aces are the opposite case. Played as one hand, two aces make a soft 12, which is a weak start. Split them and each ace is waiting on a ten-value card, which turns up nearly a third of the time. Put numbers on it and the gap is huge. Hit the soft 12 against a dealer 10 and you're at about minus 7 cents per dollar; split, and you're up to roughly plus 18. Against a 6, the split is worth roughly plus 67 cents.
Tens and fives: never split
Twenty wins far more often than it loses. Against a dealer 6, standing on 20 is worth about plus 70 cents per dollar, and splitting the tens drops that to about plus 58. Each time you do it, you give up roughly 13 cents on the dollar, or about $2.57 on a $20 bet, to swap one great hand for two decent ones.
Fives are worth more together, because 10 is a strong doubling hand. Versus a 9, doubling that 10 earns you about 14 cents per dollar. Split the fives instead and you're down about 52. So think of two fives as a ten. Double it against anything from 2 to 9; against a 10 or an ace, hit.
Every other pair, card by card
Nines: split them against 2 to 6, 8 and 9. Stand against 7, 10 or an ace. The 7 is the odd one out, and there's a reason: a dealer showing 7 very often finishes on 17, which your 18 already beats.
Sevens: split against 2 to 7. Against 8 or higher, just hit.
Sixes: split against 2 to 6, and hit against 7 or higher.
Fours: split only against a 5 or a 6. Anywhere else, hit and treat the 8 as a hand to build on.
Twos and threes: split against 2 to 7, hit against 8 or higher.
Some of these are close calls and some aren't. Fours against a 5 come out about a cent per dollar better split than hit, which barely matters. Twos against a 7 are a bigger deal: split, they're close to break-even, while hitting gives up about 9 cents. Splitting tens against a 6, as above, throws away 13.
Why the dealer's card decides it
Splitting puts more money on the table, so you want to do it when the dealer is likely to bust. Worked out for our rules, a dealer showing a 5 or a 6 busts about 42% of the time, and a 4 about 39%. Against a 7, that falls to about 26%, and a 10 or an ace bust about 23% and 17% of the time once a dealer blackjack has been ruled out.
That's the whole pattern in one place. Small dealer cards are when you want two hands working. Big ones are when you want your losses kept to one.
The rules that change the chart
Everything above assumes you can double after splitting, which our table allows. Take that away and the small pairs get split less often: twos and threes only against 4 to 7, sixes only against 3 to 6, and fours never. Nines and sevens don't change, and aces and eights are still split every time.
Our table also lets you split only once, gives split aces one card each, and pays a 21 made after a split at even money rather than 3 to 2. Tables in the blackjack section set their own rules, so read the rules panel before you sit down. The chart here is right for any game with the same core rules.
Splitting at Jacks Club
Our Blackjack deals from an infinite shoe, so every card is a fresh draw from a full deck, and every hand can be checked as provably fair once it's played. It sits with the other in-house games, from the bitcoin dice game to Crash, and returns 99.43% with correct play. Wondering whether counting cards would add anything on top? Our guide to how to count cards in blackjack explains why an infinite shoe gives a count nothing to work with, and our bitcoin blackjack guide covers the rest of the maths, insurance included.
Common questions
Should you always split aces in blackjack?
Yes. Two aces make a soft 12, which is a poor hand, while each split ace has nearly a one in three chance of drawing a ten. Splitting is the better play against every dealer card.
Should you split 8s against a dealer 10?
Yes. Sixteen against a 10 loses about 54 cents per dollar whichever way you play it, and splitting cuts that to about 49 cents. It's a smaller loss, not a win.
Can you split tens in blackjack?
Most tables allow it, but you shouldn't. Standing, a 20 against a 6 is worth about 70 cents per dollar; split, it's worth roughly 58.
Can you re-split pairs at Jacks Club?
Not on our in-house Blackjack. You can split any pair of equal value once and double on each new hand, and split aces receive one card each.