How to Split Pairs in Blackjack: The Complete Guide
When you're dealt a pair, you have the option to split it into two separate hands — each receiving a new second card — by placing a second bet equal to your original. Whether to split depends on your pair, the dealer's upcard, and whether the game allows doubling after split.
21simulator.com flags every split situation and measures your EV leak from incorrect pair decisions.
The Two Absolute Rules
Before the full table: two pair rules are unconditional. Memorize these first.
- Always split Aces. No exceptions. Two hands starting with an Ace are each dramatically stronger than a soft 12 or hard 2.
- Always split 8s. No exceptions — even vs dealer 10 or Ace. Hard 16 is the worst hand in the game. Splitting creates two new chances at a reasonable outcome. Yes, it costs money to split 8s vs a dealer 10 — it costs less money than standing on 16.
And two pairs you never split:
- Never split 5s. Hard 10 is an excellent doubling hand. Splitting turns it into two weak 5-starting hands.
- Never split 10s. Hard 20 is one of the best hands in blackjack. The EV gain from splitting in rare optimal scenarios is not worth the strategic complexity or the variance.
Complete Pair Splitting Chart (6-Deck, DAS Available)
| Your Pair | Split When | Otherwise | Notes |
|---|---|---|---|
| Aces (A-A) | Always split | — | The highest-priority split in the game. Two starting-Ace hands are each far stronger than soft 12 (playing the pair as 2+12). Most casinos allow only one card per split Ace. |
| 2s (2-2) | Dealer 2–7 | Hit | With DAS, also split vs dealer 2. Without DAS, split only vs 3–7. |
| 3s (3-3) | Dealer 2–7 | Hit | Same conditions as 2-2. With DAS, split vs 2; without DAS, split only vs 3–7. |
| 4s (4-4) | Dealer 5–6 (DAS only) | Hit | Without DAS, never split 4s — hit hard 8 instead. With DAS, splitting vs 5–6 is marginally profitable. |
| 5s (5-5) | Never split | Double vs 2–9; hit vs 10, Ace | Hard 10 is one of the best doubling hands. Never split 5s — you turn an excellent hand into two mediocre starting points. |
| 6s (6-6) | Dealer 2–6 | Hit | With DAS, also split vs 2 without restriction. Hard 12 is a losing stand hand, so splitting creates two chances against a dealer bust card. |
| 7s (7-7) | Dealer 2–7 | Hit | Hard 14 is a weak hand. Against a dealer 8+, hitting is correct. Vs 8 specifically, you might push on a dealer 15–16 — but splitting loses more than hitting. |
| 8s (8-8) | Always split | — | Hard 16 is the worst hand in blackjack. Always split 8s — even vs dealer 10 or Ace. Two independent hard-8 starting hands are significantly better than playing hard 16. |
| 9s (9-9) | Dealer 2–6, 8–9 | Stand | Stand vs dealer 7 (your hard 18 likely wins or pushes; splitting risks two losing 9-hands). Stand vs 10 and Ace (too strong a dealer position to split into two 9-hands). |
| 10s (10-10) | Never split | Always stand | Hard 20 wins the vast majority of hands. Splitting destroys one of the best possible holdings for a marginal EV gain in rare scenarios — not worth it in basic strategy. |
How DAS Changes Splitting Decisions
DAS — double after split — lets you double down on a hand created by splitting a pair. When DAS is available, several marginal splits become correct because you can extract extra money from strong post-split hands.
The key DAS impacts:
- 2s and 3s vs dealer 2: Split with DAS; hit without DAS.
- 4s vs dealer 5–6: Split with DAS; hit without DAS.
- 6s vs dealer 2: Some tables restrict 6-6 splitting to dealer 3–6 without DAS.
If you're unsure whether DAS is available, ask the dealer before your first hand. It should also be posted in the table rules.
Resplitting
If you split a pair and one of the new hands is also a pair, most casinos allow you to split again (up to a maximum of 3–4 total hands). Resplitting follows the same basic strategy rules as the initial split. The notable exception: resplitting Aces is often not allowed — check the posted rules.
Resplitting 8s is always correct when permitted and you receive another 8. Resplitting produces two more starting-8 hands, each better than hard 16.
Why Splitting 8s vs Dealer 10 Loses Less Than Standing
Splitting 8s vs a dealer 10 is the most counterintuitive split in basic strategy. Here's the EV comparison:
- Stand on hard 16 vs dealer 10: EV ≈ −0.54 per unit. The dealer completes their hand and reaches 17+ about 77% of the time.
- Hit hard 16 vs dealer 10: EV ≈ −0.54 per unit (slightly better than standing in some counts).
- Split 8-8 vs dealer 10: EV ≈ −0.48 per unit. Each new 8-starting hand has better independent chances than hard 16 — you hit, double, or stand on the next card rather than playing a 16.
Splitting still loses money on average — the dealer 10 is a strong position. But it loses less, and that is the correct criterion: minimize expected loss when all options are negative.
Pair of 9s: The Nuanced Split
The 9-9 rule trips up many players. Hard 18 feels like a strong standing hand — and it often is. The split rule:
- Split vs dealer 2–6, 8–9: Two 9-starting hands against a weak-to-moderate dealer upcard are more profitable than one 18.
- Stand vs dealer 7: Your 18 beats a dealer who completes to 17, which is the most likely outcome with a 7 upcard.
- Stand vs dealer 10, Ace: The dealer's strength makes splitting into two 9-hands worse than holding 18 and hoping for a push or win.