Free tool
Odds Converter
Decimal · American · Fractional · Implied probability
Type a price in any format. The other three update as you type, including the implied probability — the percentage the price is really quoting.
The fourth number is the one that matters
Three of these boxes are the same price in different clothes. The fourth, implied probability, is what the price is actually claiming — and it is always overstated, because the bookmaker's fee is inside it. We publish the corrected figure for every football match on the board today.
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The three formats
Decimal is the total return per unit staked, your stake included. 2.50 returns 2.50 for every 1 risked. Standard in Europe and Australia.
American splits into two cases around an even-money bet. A positive price is the profit on 100 staked; a negative price is the stake needed to profit 100. +150 and -200 are 2.50 and 1.50 in decimal. There is no such thing as a price between -99 and +99.
Fractional is profit over stake, the traditional British form. 3/2 is 2.50 decimal; 1/1 is 2.00, or evens.
Implied probability, and why it lies
Divide 1 by the decimal price and you get the percentage the price quotes: 2.50 becomes 40%. Convert every outcome in a market this way and add them up. The total will be more than 100% — often 104 to 108%. The surplus is the fee, and it is inside every one of those percentages.
To get a figure that can be read as a real chance, the fee has to come out. That is what the no-vig calculator does, and the maths page shows the arithmetic in full.
Questions
How do I convert American odds to decimal?
For a positive price, divide by 100 and add 1: +150 becomes 2.50. For a negative price, divide 100 by the price and subtract from 1: -200 becomes 1.50.
How do I convert decimal odds to implied probability?
Divide 1 by the decimal odds and multiply by 100. A price of 2.50 implies 40 percent. This figure still contains the bookmaker's margin, so it overstates the real chance.
What are fractional odds?
Fractional odds express profit over stake. 3/2 pays three units of profit for every two staked, which is 2.50 in decimal odds and 40 percent implied probability.
Why do the implied probabilities add up to more than 100 percent?
Because the bookmaker's fee is built into every price rather than charged separately. The surplus over 100 percent is the margin, also called the vig, juice or overround.