You're dealt a pair of 9s. The dealer shows a 4. Split or play it as one hand? Basic strategy answers:
| Split ← | +0.3015 |
| Stand | +0.1759 |
| Hit | -0.6175 |
| Double | -1.2349 |
| You bust on the next card | 76.9% |
| Dealer 4 busts | 39.4% |
Split is worth 0.1257 more per unit than Stand. On a $10 bet that is $1.26 handed over every time you get it wrong. Across the 340 situations in this chart it ranks 79th by expected value — better than 261 of them, worse than 78. Expected value is per unit staked, computed for multi-deck, dealer stands on soft 17, double after split allowed. The model and the code are published as data.
Against a dealer 4 (40% bust chance), splitting 9s turns one mediocre total into two playable hands while the dealer is vulnerable. With double-after-split allowed, you also keep the option to press each new hand — that's where the split profit comes from.
Note the famous 9-9 exception: against a 7 you stand, because your 18 beats the dealer's likely 17. Against 8 or 9 you split again. It's the trickiest row of the whole chart.