Probability to Odds Converter

About this calculator

Converting a probability into betting odds uses the relationship odds against = (1 − p) / p, expressed as a ratio such as "3 to 1". A probability of 25% (p = 0.25) becomes odds against of (0.75/0.25) = 3, written 3-to-1, while a coin flip's 50% probability becomes even odds, 1-to-1. The reverse direction, odds to probability, is p = 1 / (odds + 1) when odds are expressed as "n to 1" against.

Bookmakers and oddsmakers price markets in odds rather than raw probabilities because odds directly determine payouts, while bettors and analysts often prefer probabilities to compare an implied chance against their own estimate of the true likelihood, spotting value bets where the market's implied probability looks too low.