Chances for success
Chances against success
Probability of winning
Probability of losing
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Odds Calculator

By Bogna Szyk and Steven Wooding
Last updated: Sep 02, 2020

If you ever wondered about your chances of winning a bet with odds 3 to 5, our odds calculator is here to help you. Having given the betting odds, you will now be able to calculate the percentage probability of winning or losing and decide whether the reward is worth the risk. You will also find out how to calculate the odds ratio using the odds equation.

What are the odds...?

The odds are usually presented as a ratio. For example, the odds of your favorite football team losing a match maybe 1 to 5. The odds of you winning a lottery might by 1 to 10,000. On the other hand, the odds of the horse you bet on winning the race may be equal to 4 to 3.

What do these numbers mean? There are two types of odds ratios: "odds of winning" and "odds of losing". For odds of winning, the first number is the chances for success, and the second is the chances against success (of losing). For "odds of losing", the order of these numbers is switched.

Let's analyze one of these options more closely. For example, if the odds for a football team losing are 1 to 5, it means that there are five chances of them winning and only 1 of them losing. That means that if they played six times, they would win five times and lose once.

How to calculate odds

Our betting odds calculator takes a step further and calculates the percentage probability of winning and losing. The team would win 5 out of 6 games and lose 1 of them. By converting fraction to percent, we can say that the chances of winning are 5/6 = 83.33%, and of losing 1/6 = 16.67%.

Do you understand how we calculated this percentage? If not, take a look at the odds formulas:

probability of winning = chances for success / all chances

probability of losing = chances against success / all chances

all chances = chances for success + chances against success

How to use the odds ratio calculator: an example

  1. Find out what the odds are expressed as a ratio. Let's say that the odds of you winning in a school lottery are 5 to 12.
  2. Decide which number represents chances for success (for winning), and which number represents chances against success (for losing). In this case, there are five chances for success and 12 chances against success.
  3. Sum up all of the chances: 5 + 12 = 17.
  4. Calculate the probability of winning according to the odds formulas: 5/17 = 29.41%.
  5. Calculate the probability of losing according to the odds formulas: 12/17 = 70.59%.
  6. Check whether the result is correct with the betting odds calculator.
Bogna Szyk and Steven Wooding
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