Dealer bust odds by upcard
Every stand-or-hit decision in blackjack is really a bet on one number: how often the dealer busts from the card they’re showing. Here is that number for all ten upcards — computed by exact recursion over every possible dealer draw sequence, not simulated and not copied.
| Upcard | Bust (S17) | Bust (H17) | 17 | 18 | 19 | 20 | 21 |
|---|---|---|---|---|---|---|---|
| 2 | 35.36% | 35.67% | 13.98% | 13.49% | 12.97% | 12.40% | 11.80% |
| 3 | 37.39% | 37.67% | 13.50% | 13.05% | 12.56% | 12.03% | 11.47% |
| 4 | 39.45% | 39.71% | 13.05% | 12.59% | 12.14% | 11.65% | 11.12% |
| 5 | 41.64% | 41.77% | 12.23% | 12.23% | 11.77% | 11.31% | 10.82% |
| 6 | 42.32% | 43.95% | 16.54% | 10.63% | 10.63% | 10.17% | 9.72% |
| 7 | 26.23% | 26.23% | 36.86% | 13.78% | 7.86% | 7.86% | 7.41% |
| 8 | 24.47% | 24.47% | 12.86% | 35.93% | 12.86% | 6.94% | 6.94% |
| 9 | 22.84% | 22.84% | 12.00% | 12.00% | 35.08% | 12.00% | 6.08% |
| 10 | 22.98% | 22.98% | 12.07% | 12.07% | 12.07% | 37.07% | 3.74% |
| A | 16.65% | 20.07% | 18.89% | 18.89% | 18.89% | 18.89% | 7.78% |
Distributions assume US peek rules (a dealer blackjack ends the round before you act, so it is excluded) and stand-on-soft-17 unless marked H17. The pattern to internalize: 5 and 6 bust more than four times in ten — which is why basic strategy stands on totals as low as 12 against them and presses doubles — while 7 through ace complete a pat hand roughly three times in four, forcing you to keep hitting stiff totals. Click any upcard for its full breakdown and the hands it decides.
Why the cliff between 6 and 7
With 2–6 up, the dealer’s most likely hole card (a ten) leaves a stiff 12–16 that must draw again into a rich band of busting cards. With 7 or higher up, that same ten makes an instant 17–21. One rank of upcard moves the bust rate from 42% to 26% — the sharpest edge in the game, and the reason the strategy chart visibly splits into two worlds at that line.