Should you split 10s in blackjack?
No. Stand on 20, even against a dealer 5 or 6.
Expected result per unit bet on a 6-deck table where the dealer hits soft 17, with surrender (the common Las Vegas Strip game): Stand +0.6766 · Split +0.4542.
Practice on this table in the trainerBasic strategy chart for this table
The hand
You
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Dealer
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| Play | Expected result |
|---|---|
| StandBest | +0.6766 |
| Split | +0.4542 |
| Surrender | −0.5000 |
| Hit | −0.8529 |
| Double | −1.7058 |
Average win or loss per unit of the original bet (−0.5000 loses half the bet on average), computed exactly from the cards left in the shoe, with perfect play afterwards. In US games the numbers are after the dealer has checked for blackjack.
Why
A 20 beats everything the dealer can make except 21. Splitting trades one hand that wins most of the time for two hands that each start from 10: good starts, but worth less than the 20 even against the dealer’s weakest cards. Card counters split tens against a 5 or 6 only when the cards left are unusually rich in tens, which basic strategy doesn’t assume.
Do the table rules change the answer?
The answer is the same on all 7 tables below.
| Table | Stand | Split |
|---|---|---|
| 6 decks · H17 · DAS · surrender | +0.6766 | +0.4542 |
| 6 decks · S17 · DAS · surrender | +0.7028 | +0.4522 |
| 8 decks · H17 · DAS · surrender | +0.6770 | +0.4582 |
| 2 decks · H17 · DAS | +0.6733 | +0.4218 |
| 1 deck · H17 · no DAS | +0.6683 | +0.3721 |
| 1 deck · S17 · no DAS | +0.6974 | +0.3788 |
| European: 6 decks · S17 · DAS · no hole card | +0.7028 | +0.5668 |
H17: the dealer hits soft 17. S17: the dealer stands on soft 17. DAS: you can double after splitting. European tables have no hole card, so the dealer only checks for blackjack after you play: those numbers include losing everything you bet to a dealer blackjack. They also allow doubling on 9 to 11 only and one split.
Against every dealer up card
The same hand against each up card, on 6 decks · H17 · DAS · surrender.
| Dealer | Stand | Split |
|---|---|---|
| 2 | +0.6329 | +0.1201 |
| 3 | +0.6436 | +0.1999 |
| 4 | +0.6543 | +0.2834 |
| 5 | +0.6689 | +0.3753 |
| 6 | +0.6766 | +0.4542 |
| 7 | +0.7720 | +0.2886 |
| 8 | +0.7904 | +0.0539 |
| 9 | +0.7561 | −0.2176 |
| 10 | +0.5591 | −0.3666 |
| A | +0.6003 | −0.4010 |