Calculadora de Odds
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
odds = P / (1 − P)
About this calculator
The Odds Calculator converts a probability (P) into odds, representing the ratio of the chance of an event occurring to the chance of it not occurring. The formula used is odds = P / (1 − P), where P is a number between 0 and 1. For example, if the probability of rain is 0.75, the odds are 0.75 / 0.25 = 3, indicating that rain is three times more likely than no rain.
This tool is useful in contexts such as sports betting, risk analysis, gambling, and statistics. Odds are often used to express probabilities intuitively, especially in comparisons. By entering the probability as a percentage (e.g., 75%) or decimal (0.75), the calculator returns the corresponding odds.
Cautions: the probability must be between 0% and 100% (excluding 0% and 100%, as they would result in zero or infinite odds). Odds above 1 indicate the event is more likely to occur than not; below 1, the opposite. Remember that odds and probability are different ways of measuring the same uncertainty.
Frequently asked questions
What does odds 3 to 1 mean?
Odds 3 to 1 (3:1) mean that for every 4 attempts, the event occurs 3 times and does not occur 1 time. The corresponding probability is 3/(3+1) = 0.75 or 75%.
How do I convert odds to probability?
To convert odds (O) to probability, use the formula P = O / (1 + O). For example, odds 2 become probability 2/3 ≈ 0.6667.
Can I use the calculator for decimal betting odds?
Yes. Decimal odds (e.g., 2.50) represent total return per unit staked. Our calculator works with probability odds, but you can convert: decimal odds = 1 / P.
What happens if I enter 0% or 100%?
0% probability results in odds of zero (impossible event). 100% probability results in infinite odds (certain event). The calculator may return an error or infinity.