Implied Probability Calculator (Odds to Percentage)
Enter odds in any format and the tool shows the implied probability (the chance the price bakes in), along with the same odds in decimal, American, fractional, probability and cents.
Fill in the fields above to see the result.
Odds are probability wearing the costume of a price. The calculator above does the translation: give it the odds and it returns the chance that number represents. It is the first conversion every bettor needs to automate mentally, because comparing 2.10 against 2.15 tells you nothing, and comparing 47.6% against 46.5% tells you everything.
How the math works
With decimal odds it is one division:
implied probability = 1 ÷ odds
Odds of 2.00 imply 1 ÷ 2.00 = 50%. Odds of 4.00 imply 25%. The longer the odds, the smaller the chance the price is assigning.
The way back is the same thing mirrored:
fair odds = 1 ÷ probability
If you think something happens 40% of the time, the price that pays exactly fair is 1 ÷ 0.40 = 2.50. Above that you are being paid more than the risk asks for. Below it, less.
Worked example
| Odds | Implied probability | Reading |
|---|---|---|
| 1.50 | 66.67% | Clear favourite |
| 1.91 | 52.36% | Near coin flip, with the commission |
| 2.00 | 50.00% | Exact coin flip |
| 2.50 | 40.00% | Slight underdog |
| 4.00 | 25.00% | One in four |
| 10.00 | 10.00% | One in ten |
Look at the 1.91 row. That is the classic price on both sides of a balanced market. Each side implies 52.36%, and the two together add up to 104.71%. Since only one can happen, that 4.71% of excess is not probability: it is the bookmaker's commission.
This is how you see that raw implied probability is not true probability. It always arrives inflated, and the size of the inflation is the margin.
Where it misleads
Implied is not true. The book's price carries their margin. Treating 1 ÷ odds as the real chance makes every bet look bad, because you are counting the commission against yourself.
The conversion does not judge the price. It only translates. Knowing 2.10 implies 47.6% does not tell you the bet is good; it tells you what you need to believe for it to be.
Comparing books requires the same format. American, fractional and decimal odds describe the same thing in different clothes, and comparing mixed formats is the fastest way to get a decision wrong.
FAQ
Why do the probabilities in a market add up to more than 100%?
Because the bookmaker needs their margin. That excess is the price of the service. The margin calculator measures exactly how much.
How do I turn implied into true probability?
By removing the margin. You need the prices of every outcome in the market to redistribute the excess. The no-vig calculator does that step.
What is the implied probability of American odds?
For a positive line, 100 ÷ (line + 100). For a negative one, −line ÷ (−line + 100). A line of +110 implies 47.6%, and −110 implies 52.4%. The odds converter handles that and every other format.
Once converted, the next step is comparing against your own estimate: the EV calculator says whether the gap is worth money. The implied probability guide covers each format. Betting is entertainment for adults 18 and over and carries a risk of loss.