Updated 2026-07-22 · 8 decks · S17 · DAS · methodology
Soft 20 (A,9) vs dealer Ace: the verdict
The math is in: stand. Against a dealer Ace, soft 20 (a,9) does best by letting the dealer take the risk of busting.
The numbers
| Action | Win | Push | Lose | EV per $1 |
|---|---|---|---|---|
| Stand | 73.3% | 18.9% | 7.8% | +0.655 |
| Hit | 47.2% | 13.6% | 39.1% | +0.081 |
| Double | 44.3% | 10.8% | 45.0% | −0.014 |
Why stand is correct
A dealer showing Ace busts 16.7% of the time, and that bust chance is doing the work here: standing wins 73.3% of hands without ever risking your own bust. Drawing a card would improve the total sometimes, but the bust risk and the hands you’d ruin cost more than they gain.
For context, a dealer Ace finishes on 17–20 about 75.6% of the time, on 21 7.8%, and busts 16.7%. Those dealer outcomes are the same no matter what you hold — the whole game is choosing the action whose distribution fits them best.
What the mistake costs
Choosing hit instead of stand costs about $1435 per 100 such hands at $25 a hand (−0.574 EV per dollar). The genuinely expensive error here is double: −0.670 per dollar, or roughly $1674 per 100 hands at the same stakes.
Does the rule set change it?
No — stand holds across every common configuration: Vegas Strip, Atlantic City with late surrender, H17 games and European no-hole-card tables all agree here.
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soft 20 against other dealer cards:
Other key hands vs a dealer Ace: