Blackjack Odds and Probabilities

Behind every blackjack decision lies probability. Understanding a few key numbers helps you see why basic strategy recommends what it does. This page explains the most useful odds in plain language. Exact figures vary slightly with the number of decks and the table rules.

How often does the dealer bust?

The dealer must draw until reaching at least 17. How often that ends in a bust depends heavily on the upcard:

• Dealer shows 2 to 6: the dealer busts roughly 35 to 42 percent of the time, with 5 and 6 the weakest cards.
• Dealer shows 7 to 10: the bust rate drops to roughly 21 to 26 percent.
• Dealer shows an ace: the dealer busts least often.

This is why basic strategy often tells you to stand on a weak total against a 4, 5 or 6.

Probability of a natural blackjack

The chance of being dealt a blackjack, an ace plus a ten-value card, is about 4.8 percent, or roughly once every 21 hands. Because a natural is relatively rare, its payout matters a great deal. Read why on our page about house edge and rule variations.

Busting when you hit

The chance that one more card takes you over 21 depends on your total:

• Hard 12: you bust with any ten-value card, about 31 percent of the time.
• Hard 16: you bust with anything above a 5, around 62 percent of the time.
• Hard 11 or lower: you cannot bust with one card.

Even so, hitting a hard 16 against a dealer 10 is still the better choice, because standing loses even more often.

Why insurance is a poor bet

When the dealer shows an ace, you can take insurance: a side bet that pays 2 to 1 if the dealer has blackjack. Roughly 30 percent of the remaining cards are ten-value cards, but you need more than a third to break even. As a result, insurance carries a house edge of around 7 percent for players who do not count cards.

Short-term results

Probabilities describe the long run. In a single session, anything can happen: you can lose many hands in a row or win more than expected. That is normal variance. Plan for it with a fixed budget, as explained in bankroll and session planning.

Blackjack is a game of chance for adults (18+). Play responsibly.