What Is Dealer Bust Probability in Blackjack?
The single upcard the dealer shows you drives nearly every basic strategy decision — because it drives how likely the dealer is to bust.
Short answer
Dealer bust probability is the chance that the dealer's hand goes over 21 once they finish drawing, given only their visible upcard. It's higher for weak upcards (2 through 6) and lower for strong ones (7 through Ace), because the dealer has no choice about how to play — house rules force the dealer to keep hitting any total under 17, with no option to stand early the way a player can.
Dealer bust probability by upcard
Dealer stands on soft 17 (the site's default rule). For a 10 or Ace upcard, the figure assumes the dealer has already checked and does not have blackjack. That's the situation you are deciding in, and it's the same number the trainer shows.
| Dealer upcard | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | A |
|---|---|---|---|---|---|---|---|---|---|---|
| Bust probability | 35.4% | 37.4% | 39.4% | 41.6% | 42.3% | 26.2% | 24.5% | 22.8% | 23.0% | 16.7% |
Three things stand out:
- The cliff between 6 and 7. Bust probability drops from 42.3% to 26.2%. A dealer 6 with a ten-value hole card has 16 and must draw again. A dealer 7 with the same hole card has 17 and stops. That gap is why so many hit/stand lines in basic strategy change at exactly this point.
- 6 is the weakest upcard, not 5. The two are close (42.3% vs 41.6%), but 6 busts slightly more often.
- An Ace busts least. Even once blackjack is ruled out, a dealer Ace busts only 16.7% of the time.
If the dealer hits soft 17 (H17)
Under H17 the dealer draws again on hands like Ace + 6 instead of standing. That changes only the upcards below; 7, 8, 9 and 10 stay exactly the same as in the table above.
| Dealer upcard | 2 | 3 | 4 | 5 | 6 | A |
|---|---|---|---|---|---|---|
| S17 (stands on soft 17) | 35.4% | 37.4% | 39.4% | 41.6% | 42.3% | 16.7% |
| H17 (hits soft 17) | 35.7% | 37.7% | 39.7% | 41.8% | 43.9% | 20.1% |
The biggest changes are for a dealer 6 (+1.6 points) and a dealer Ace (+3.4 points), the two upcards that most often reach soft 17.
How the dealer's hand finishes
Busting is only one of six ways the dealer's hand can end. Here is the full distribution of final totals for each upcard (dealer stands on soft 17; for a 10 or Ace, after the dealer has checked for blackjack). Rows may not add up to exactly 100% because of rounding.
| Dealer upcard | 17 | 18 | 19 | 20 | 21 | Bust |
|---|---|---|---|---|---|---|
| 2 | 14.0% | 13.5% | 13.0% | 12.4% | 11.8% | 35.4% |
| 3 | 13.5% | 13.0% | 12.6% | 12.0% | 11.5% | 37.4% |
| 4 | 13.0% | 12.6% | 12.1% | 11.6% | 11.1% | 39.4% |
| 5 | 12.2% | 12.2% | 11.8% | 11.3% | 10.8% | 41.6% |
| 6 | 16.5% | 10.6% | 10.6% | 10.2% | 9.7% | 42.3% |
| 7 | 36.9% | 13.8% | 7.9% | 7.9% | 7.4% | 26.2% |
| 8 | 12.9% | 35.9% | 12.9% | 6.9% | 6.9% | 24.5% |
| 9 | 12.0% | 12.0% | 35.1% | 12.0% | 6.1% | 22.8% |
| 10 | 12.1% | 12.1% | 12.1% | 37.1% | 3.7% | 23.0% |
| A | 18.9% | 18.9% | 18.9% | 18.9% | 7.8% | 16.7% |
Look along the diagonal: a dealer 7 most often finishes on 17 (36.9%), an 8 on 18 (35.9%), a 9 on 19 (35.1%) and a 10 on 20 (37.1%). A ten-value hole card, the most common card, completes those hands immediately. That's also why 18 is a weak total against a dealer 9: the dealer finishes on 19 or better 53.2% of the time and busts only 22.8%. A dealer Ace is the most spread out, ending on each of 17 through 20 about 18.9% of the time.
Why the dealer can't play like a player
A player can stand on a weak total to avoid busting. A dealer can't — the rules require hitting any hand under 17 (and, at many tables, hitting a soft 17 too). That forced play is exactly why the dealer's upcard is such a strong signal: a dealer showing a 5 or 6 has to keep drawing from a shoe where a large share of the remaining cards are ten-value, which pushes their total past 21 relatively often. A dealer showing a 9, 10, or Ace usually only needs one or two more cards to reach a strong total, so there's much less room for a bust.
How it shapes basic strategy
This single number is the reason the same player total can call for completely different actions depending on the dealer's card. A hard 14, for example, stands against a dealer 6 (their bust risk is high enough that standing lets it work in your favor) but hits against a dealer 9 (their bust risk is low enough that standing usually just hands them the win). Nearly every row of the basic strategy chart reflects this same logic playing out across the dealer's ten possible upcards.
Bust probability vs. final result
Dealer bust probability only describes what happens once the dealer plays out their hand — it's not the same as your win probability, which also depends on your own total and what happens if the dealer doesn't bust. A high dealer bust probability makes standing more attractive on marginal hands, but it doesn't guarantee a win; the dealer still completes a strong hand a meaningful share of the time even against their weakest upcards.
What a "weak" dealer 6 really means
A dealer 6 busts 42.3% of the time, more than any other upcard, which makes it the best upcard for the player. Averaged over every starting hand played its best way, a player can expect about +23% of the bet per hand against a dealer 6.
That average mixes good starts with bad ones. A 20 or an 11 is a big favorite. A hard 12–16 that stands, though, wins only the 42.3% of the time the dealer busts and loses the other 57.7% — a dealer who doesn't bust always finishes on at least 17. Standing is still correct because it loses less than hitting: for a 13, standing has an EV of −0.154 and hitting −0.236.
| Your hand | Best play | Win | Push | Lose | EV |
|---|---|---|---|---|---|
| 20 | Stand | 80.1% | 10.2% | 9.7% | +0.704 |
| 11 | Double | 63.3% | 6.7% | 30.0% | +0.667 |
| 8,8 | Split | 52.6% | 6.4% | 41.1% | +0.326 |
| 12 · 13 · 16 | Stand | 42.3% | 0.0% | 57.7% | -0.154 |
Even against a dealer 6, about 39% of starting hands lose money on average with their best play. So the "right" basic strategy move isn't a way to win that hand — it's the choice that loses the least (or wins the most) on average. Why stand on 12 vs 4? shows the same idea in another spot.
Where the number comes from
These figures aren't copied from a reference table. Blackjack Decision Lab's probability engine computes them by working through every possible sequence of cards the dealer could draw, under your selected soft-17 rule. It uses an infinite-deck approximation, where each card rank keeps the same probability on every draw. The results stay within about 0.2 percentage points of an exact 6-deck calculation. See How It Works for the full calculation process, or watch the live bust probability update for each hand in the trainer.
See Dealer Bust Probability Live