Decisions assume multi-deck S17 with DAS allowed (the most common ruleset). Source: Wizard of Odds, Blackjack Apprenticeship.
A friend of mine once split 10s against a dealer 6. "The dealer's going to bust," he said, sliding out a second stack of chips with the confidence of someone who'd never consulted a strategy chart in his life.
He turned a beautiful 20 — a hand that wins roughly 85% of the time — into two mediocre hands and ended up losing both.
That's the thing about splitting: when you get it right, you turn one losing hand into two winning ones. When you get it wrong, you turn one winner into two losers. The margin between those outcomes often comes down to a single pair and a single dealer card.
What Does It Mean to Split in Blackjack?
When your first two cards have the same value — like two 8s, two Queens, or two 4s — you can split them into two separate hands. You place a second bet equal to your original wager, and the dealer separates the pair, dealing one new card to each.
From that point on, you play each hand independently: hit, stand, double down — whatever the situation calls for.
Place your matching bet beside (not on top of) your original chips, then hold up two fingers in a V shape — like a peace sign. The dealer does the rest.
Key rules about splitting
- You can only split on your initial two-card hand — not after hitting
- Most casinos allow you to split any pair of equal-value cards (including J-Q or 10-K)
- After splitting, if you get another matching card, most tables let you re-split up to 3 or 4 total hands
- Aces are restricted: most casinos deal only one card per split Ace, no further hitting
- A 10 drawn to a split Ace counts as 21 but typically pays 1:1 (not 3:2 like a natural blackjack)
- DAS — some tables allow you to double down on a split hand. Player-favorable, changes several decisions.
The Complete Splitting Chart
Multi-deck S17 with DAS allowed. Y = Split, N = Don't split.
| Pair | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | A |
|---|---|---|---|---|---|---|---|---|---|---|
| A-A | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 10-10 | N | N | N | N | N | N | N | N | N | N |
| 9-9 | Y | Y | Y | Y | Y | N | Y | Y | N | N |
| 8-8 | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 7-7 | Y | Y | Y | Y | Y | Y | N | N | N | N |
| 6-6 | Y | Y | Y | Y | Y | N | N | N | N | N |
| 5-5 | N | N | N | N | N | N | N | N | N | N |
| 4-4 | N | N | N | Y | Y | N | N | N | N | N |
| 3-3 | Y | Y | Y | Y | Y | Y | N | N | N | N |
| 2-2 | Y | Y | Y | Y | Y | Y | N | N | N | N |
If DAS is not allowed: 2-2 and 3-3 don't split against dealer 2 or 3, 4-4 never splits, and 6-6 doesn't split against dealer 2. Always check the table rules.
The Two Rules That Never Change
A pair of Aces is worth either 2 or 12 — both terrible totals. Split them, and you start two hands each worth 11 — one of the strongest starting positions in the game. ~31% chance of drawing a 10 for 21.
A pair of 8s totals 16 — statistically the worst hand in blackjack. Splitting converts a guaranteed loser into two hands with fighting chances. Even against dealer 10 or Ace.
Why split Aces
With each new hand starting at 11, there's roughly a 31% chance of drawing a 10-value card for 21. Even if you don't hit 21, an 11 base is strong enough to build a winning hand against almost any dealer card.
Casinos know how powerful split Aces are, which is why they restrict them: usually only one card per Ace, no re-splitting, and 21 on a split Ace pays 1:1 instead of 3:2. Even with these restrictions, splitting is overwhelmingly correct. Ed Thorp proved this on an IBM 704 back in 1962 when he published Beat the Dealer.
Why split 8s — even against a dealer 10 or Ace
A pair of 8s totals 16. If you hit, there's a 62% chance of busting. If you stand, the dealer makes 17+ about 77% of the time against most up cards. You lose either way.
This is the part most people struggle with. Yes, you're putting more money on the table against the dealer's strongest cards. But the alternative — playing hard 16 — is even worse. Simulations show splitting 8s vs dealer 10 loses less per dollar than hitting or standing on 16.
The Two Pairs You Should Never Split
Two 10s equals 20. Wins ~85% of the time against any dealer card. Splitting turns one near-guaranteed winner into two hands starting at 10. Just stand and collect.
A pair of 5s is hard 10 — one of the best doubling hands in the game. Splitting turns gold into dirt: two weak hands each starting at 5. Treat 5-5 as hard 10 and double accordingly.
Splitting 10s "because the dealer's going to bust" is one of the most expensive mistakes in blackjack. Standing on 20 wins ~85% of the time. Splitting wins ~64% combined. You'd need to win both split hands just to match the profit of standing. Don't do it.
Every Other Pair: The Detailed Breakdown
9-9: Split against 2–6 and 8–9. Stand against 7, 10, Ace.
A pair of 9s totals 18 — a solid hand. So why split it? Against dealer 2 through 6, the dealer is likely to bust (35–43% chance), and two hands starting at 9 can both reach 19+ with a face card draw.
Your 18 beats the dealer's most likely outcome (17) about 63% of the time. Splitting would break up a winning hand into two that each need to independently beat 17. Not worth it. Against dealer 10 and Ace, the dealer is too strong — splitting creates two hands even more likely to lose.
7-7: Split against 2–7. Hit against 8+.
A pair of 7s totals 14 — a stiff hand you'd normally hit against strong dealer cards. Splitting against dealer 2–7 gives you two hands starting at 7, each with potential to reach 17 (with a face card). Against dealer 8 or higher, the dealer is too strong for split 7s to be profitable.
6-6: Split against 2–6. Hit against 7+.
Similar logic to 7-7 but narrower. A pair of 6s is hard 12, which you'd normally stand on against dealer 4–6 and hit against everything else. Splitting against bust cards (2–6) gives you two fresh chances; against 7+, your split 6s become weak starting hands against strong dealers.
4-4: Split only against 5–6 (with DAS). Otherwise hit.
A pair of 4s totals 8. If you can double after splitting and draw a 7 for 11, you've created a prime doubling opportunity. That secondary value is what makes the split worthwhile against dealer 5 and 6 specifically. Without DAS, never split 4-4. Just hit your hard 8.
3-3 and 2-2: Split against 2–7 (with DAS). Otherwise hit.
Same principle for both. The split value comes from DAS — if you draw a 7 or 8 to a small pair, you're sitting on a strong doubling hand (10 or 11). Without DAS, the split window narrows to dealer 4–7 only.
DAS: The Rule That Changes Everything
DAS (Double After Split) means you can double down on any hand created by splitting. This sounds minor, but it fundamentally changes the math on several pairs.
Without DAS, splitting 2-2 against a dealer 3 is slightly negative. With DAS, the possibility of drawing a 9 (making 11) and then doubling creates enough extra value to flip the decision.
One of the first rules you should check before sitting down. Most American casinos — especially Atlantic City — allow DAS. Some European blackjack games and restrictive tables don't.
| Rule | Effect on Splitting Decisions |
|---|---|
| DAS allowed | More pairs worth splitting (2s, 3s, 4s, 6s gain value) |
| DAS not allowed | Fewer splits — 4-4 never splits, small pairs split less often |
| Re-split allowed | More aggressive on all splits (extra equity from potential re-splits) |
| Re-split Aces restricted | Still always split first time — just no second split |
Common Splitting Mistakes
Even against a dealer 6 (42% bust rate), your 20 wins more often than two split hands starting at 10. Standing wins ~85%. Splitting wins ~64% combined. Don't do it.
Putting more money out against a 10 feels awful. But hard 16 vs 10 is the worst spot in blackjack. Splitting at least gives you a fighting chance. Every simulation confirms this.
A pair of 5s should excite you — it's hard 10, a prime doubling hand. Splitting turns gold into dirt.
Using a DAS chart at a no-DAS table (or vice versa) means several wrong decisions per session. Always check the table felt or rules page.
Splitting is pure math. "I have a good feeling about this" has a negative expected value at the blackjack table. Trust the chart. Every time.
Frequently Asked Questions
Can I split any two cards that add up to the same value?
At most casinos, you can split any two cards of equal rank — and many also let you split any two 10-value cards (like J-Q or 10-K), even though they're different ranks. Some casinos restrict this to identical cards only. Check the house rules.
How many times can I re-split?
Most casinos allow splitting up to 3 or 4 total hands. Re-splitting Aces is often restricted — many tables allow only one split of Aces.
Does a 10 on a split Ace count as blackjack?
No. A split Ace plus a 10-value card pays 1:1 (even money), not the 3:2 bonus that a natural blackjack gets. It's still 21, but it's treated as a regular win.
Should I split 9s against a dealer 7?
No — stand. Your 18 beats the dealer's most likely outcome (17) about 63% of the time. Splitting breaks up a winning hand.
What if I can't afford to split?
If your bankroll can't cover the second bet, you can't split — you'll have to play the pair as a single hand. This is why bankroll management matters: always have enough to take advantage of profitable split opportunities.
📚 Sources & References
- Wikipedia — "Aces and Eights in Blackjack": Historical background and probability foundation for the always-split rule. en.wikipedia.org
- Casino.org — "How to Split in Blackjack": Mechanics, signaling, and decision framework. casino.org
- Blackjack Apprenticeship — "Strategy Charts": Pair-by-pair EV analysis with DAS variants. blackjackapprenticeship.com
- PlayOJO — "How to Split": Beginner-focused guidance on splitting basics. playojo.com
- Outplayed — "When Can You Split": Rule variations and re-split details. outplayed.com
- GamesHub — "When to Split": Casino-side perspective on common splits. gameshub.com
- Casino Player Magazine — "When to Split": Pair-by-pair decision analysis. casinocenter.com