You hold Ace-4 — a soft 15, meaning the ace still counts as 11. Dealer shows 10. The correct basic-strategy play:
| Hit ← | -0.1737 |
| Double | -0.5140 |
| Stand | -0.5404 |
| You bust on the next card | 0.0% |
| Dealer 10 busts | 23.0% |
Hit is not close: it beats Double by 0.3403 per unit. Getting this one wrong costs $3.40 on a $10 bet, every single time. Across the 340 situations in this chart it ranks 252nd by expected value — better than 88 of them, worse than 251. 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.
The beauty of soft 15 (Ace-4): you cannot bust — the ace simply drops to 1 if the card is big. Against a dealer 10 (only 21% bust chance), your current total isn't good enough to stand on, and doubling doesn't pay against a card this strong. Free shot at improving: take it.
Soft hands are where most casual players leak the most: they play them like hard totals and miss every profitable double. Learning the six soft-total rows of the chart is the fastest win-rate upgrade there is.