Splitting Pairs in Blackjack: The Rules
Last reviewed: October 2026
Splitting adds a second wager and turns a pair into two hands. For the common multi-deck rules below, split aces and eights, keep tens together, and use the dealer’s upcard for the other pairs.
What splitting does
Start with a $10 bet and a pair. Splitting adds another $10, leaving one original card and one $10 wager on each hand. You play them separately, but they share the same dealer result and draw from the same shoe. Their outcomes are not statistically independent.
The comparison is the combined expected profit or loss from both split hands versus playing the original hand. Splitting can be correct even when all available choices have a negative expected value.
The complete split chart
This table assumes four to eight decks, dealer stands on soft 17 (S17), doubling after splitting (DAS), and a US-style dealer blackjack check before you act. It shows decisions when surrender is unavailable and you may legally split. Different deck counts, no-hole-card rules, and restrictions on doubling need their own chart.
| Pair | Split against these dealer upcards | Otherwise |
|---|---|---|
| A/A | 2 through ace | Split whenever allowed under these rules |
| 2/2 | 2 through 7 | Hit |
| 3/3 | 2 through 7 | Hit |
| 4/4 | 5 or 6 | Hit |
| 5/5 | None | Play hard 10: double against 2 through 9 if allowed; otherwise hit |
| 6/6 | 2 through 6 | Hit |
| 7/7 | 2 through 7 | Hit |
| 8/8 | 2 through ace | Split whenever allowed under these rules |
| 9/9 | 2 through 6, 8, or 9 | Stand against 7, 10, or ace |
| 10/10 | None | Stand |
This matches the pair decisions in the multi-deck basic strategy reference. With late surrender, S17 still calls for splitting eights. Against an ace in a multi-deck H17 game, surrender a pair of eights if late surrender is offered. See surrender rules.
Why aces are always split
Within the stated rules, two separate ace starts are worth more than playing A-A together. The original hand is soft 12, not a hard total: the ace counted as 11 can fall to 1, so taking another card cannot immediately bust it.
Splitting aces commonly allows only one extra card per hand. An ace plus a ten after the split is usually an ordinary 21 paid at even money, not a natural paid at 3:2. Those restrictions matter and belong in the rule set used for the decision.
Why 8s are always split
Keeping 8-8 leaves hard 16. If you hit, any 6, 7, 8, 9, or ten-value card busts you. In an infinite-deck approximation, that is 8 of 13 rank-weight units, or 61.54%. A finite shoe’s exact probability changes with the cards already removed.
Splitting opens different paths: 8 plus 2 makes hard 10, and 8 plus 3 makes hard 11. Neither is soft because neither contains an ace. They may become doubling opportunities under DAS. Against a strong dealer upcard, splitting can simply lose less on average than keeping the 16; it does not guarantee a profitable situation.
Why 10s and 5s are never split
Under this basic strategy, keep the 20 made by two tens. It is already strong, although its win probability varies with the dealer’s upcard and the rules. It does not win a fixed 97% of the time.
There is no rule that both split-ten hands must finish at 20 or 21 to break even. Without further doubles, one $10 win and one $10 loss cancel, even if the winning hand was 18. The reason to stand is that keeping the original 20 has the better expected value.
Two fives make hard 10. Against dealer 2 through 9, double if permitted. Against a ten or ace, hit. Splitting throws away that useful combined starting total.
Conditional pairs: reading the dealer upcard
Do not read a dealer upcard as the dealer’s final hand. Your 18 does not automatically lose because the dealer shows 9; the dealer may finish below 18, tie it, beat it, or bust.
The pair of nines is a useful drill: split against 8 and 9, but stand against 7, 10, and ace under this chart. Memorize the actual decisions rather than trying to force them into “split against every weak card.”
Resplitting and doubling after splitting
Check how many hands the table permits, whether aces can be resplit, and whether you can draw again to split aces. Once you reach the split limit, an instruction to split is no longer available; play the resulting total under the remaining rules.
Without DAS, the chart changes. For these multi-deck S17 rules, hit 2-2 and 3-3 against dealer 2 or 3, hit 4-4 against all upcards, and hit 6-6 against dealer 2. More details are in the basic strategy math guide.
How splitting fits into overall basic strategy
Use the full basic strategy for surrender, splits, doubles, and hit-or-stand decisions. Then practice in the blackjack trainer with matching rules. Correct splitting reduces avoidable losses; it does not remove the house edge or make additional wagers risk-free.
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