Bust

Busting in blackjack occurs when a hand's total exceeds 21, resulting in an automatic loss regardless of what happens to the dealer's hand. If you are dealt a 10 and a 7 (hard 17) and choose to hit, drawing a 9 gives you a total of 26, which is a bust. Your bet is immediately collected.

The bust is central to the house edge in blackjack. The player must act first, which means if the player busts, they lose even if the dealer would have also busted on the same hand. This sequential structure is the casino's primary advantage. Approximately 28% of all player hands result in a bust when following basic strategy.

The probability of busting varies significantly based on your hand total. Hard 21 cannot bust (no reason to hit). Hard 20 busts 92% of the time when hit. Hard 17 busts about 69% of the time. Hard 12 busts only about 31% of the time. These bust probabilities are why basic strategy dictates different actions at different hand totals.

The dealer also busts, and the frequency depends on their upcard. Dealers bust approximately 42% of the time when showing a 5 or 6 (their weakest upcards) and only about 17% when showing a 7 through Ace. Basic strategy capitalizes on this by being more conservative (standing on lower totals) against weak dealer upcards and more aggressive (hitting more often) against strong ones.