Break-Even Probability

Break-even probability is the minimum win rate you need to neither profit nor lose over the long run at specific odds.

It equals the implied probability of the odds (before accounting for vig). If you're getting -110 odds, you need to win 52.4% of the time just to break even.

This concept is fundamental to value betting: if you believe the true probability is higher than the break-even probability, the bet has positive expected value.