Should you split 4s against a dealer 5?
Split them if you can double after splitting. If you can’t, hit, or double in single deck.
Expected result per unit bet on a 6-deck table where the dealer hits soft 17, with surrender (the common Las Vegas Strip game): Split +0.1130 · Hit +0.0828 · Double +0.0269.
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 |
|---|---|
| SplitBest | +0.1130 |
| Hit | +0.0828 |
| Double | +0.0269 |
| Stand | −0.1538 |
| Surrender | −0.5000 |
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
Each 4 has a good chance to grow into a 9, 10 or 11 that you can double against a weak dealer card, which is where the split earns its money. Without double after split that edge is gone, and a total of 8 is better played as one hand. The tables below show the single-deck games, which don’t allow doubling after a split.
Do the table rules change the answer?
The answer changes on 3 of the 8 tables below, highlighted.
| Table | Split | Double | Hit |
|---|---|---|---|
| 6 decks · H17 · DAS · surrender | +0.1130 | +0.0269 | +0.0828 |
| 6 decks · S17 · DAS · surrender | +0.1100 | +0.0277 | +0.0836 |
| 8 decks · H17 · DAS · surrender | +0.1059 | +0.0208 | +0.0796 |
| 2 decks · H17 · DAS | +0.1709 | +0.0781 | +0.1097 |
| 1 deck · H17 · no DAS | +0.0899 | +0.1621 | +0.1534 |
| 1 deck · S17 · no DAS | +0.0867 | +0.1623 | +0.1539 |
| European: 6 decks · S17 · DAS · no hole card | +0.1006 | — | +0.0836 |
| 6 decks · H17 · no DAS · surrender | −0.0186 | +0.0269 | +0.0828 |
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 | Split | Double | Hit |
|---|---|---|---|
| 2 | −0.1817 | −0.2020 | −0.0222 |
| 3 | −0.0894 | −0.1284 | +0.0093 |
| 4 | +0.0086 | −0.0509 | +0.0463 |
| 5 | +0.1130 | +0.0269 | +0.0828 |
| 6 | +0.2050 | +0.0929 | +0.1134 |
| 7 | −0.1688 | −0.1751 | +0.0866 |
| 8 | −0.3252 | −0.4510 | −0.0591 |
| 9 | −0.5077 | −0.7157 | −0.2098 |
| 10 | −0.6184 | −0.7451 | −0.2480 |
| A | −0.6360 | −0.8294 | −0.2639 |