Statistics Calculators

Odds Calculator

Convert a probability percentage into odds in favor and odds against, expressed as a simplified ratio.

Odds in favor —

Odds against —

Decimal odds (for : against) —

About the Odds Calculator

Odds and probability both describe likelihood, but they're expressed differently. Probability compares favorable outcomes to all outcomes, while odds compare favorable outcomes directly to unfavorable ones.

Formula: Odds in favor = P ÷ (1 − P), simplified to a whole-number ratio · Odds against is the inverse ratio

A probability of 25% converts to odds of 1 : 3 in favor (one favorable outcome for every three unfavorable ones). This conversion is common in betting markets, genetics, and risk communication.