How to read decimal, fractional and American odds
Updated 13 Nov 2026 · 3 min read
A bookmaker can write the same price in three ways, and each way hides the same two facts: what a winning bet pays and how likely the bookmaker thinks it is. This guide reads all three formats with one example and shows where the chance comes from.
Decimal odds: the whole return on one unit
A decimal price is what you get back for every unit you stake, with the stake included. At 2.50, a stake of 100 returns 250: your 100 plus 150 of profit. A price of 2.00 doubles the stake and is called even money.
Decimal is the easiest format to compare, because a higher number always pays more.
Fractional odds: profit over stake
A fraction leaves the stake out. The same price is 3/2: three units of profit for every two staked. Add one to the fraction and you are back at the decimal price.
Fractions under one, such as 1/2, mean the profit is smaller than the stake. That is a favourite.
American odds: one number with a sign
A positive American price says how much profit a stake of 100 makes, so 2.50 becomes +150. A negative price says how much you must stake to win 100: a favourite at 1.50 is written −200, meaning 200 staked for 100 of profit.
The sign flips at even money. Above 2.00 the number is positive, below it negative.
From a price to a probability
Divide one by the decimal price and you get the chance the price implies. At 2.50 that is 40.00%; at 1.50 it is 66.67%. A bet at a given price breaks even only if it wins at least that often.
The odds converter does all four steps at once, from any of the three formats.
Why the chances add up to more than the whole
Take a market with two equal sides, each priced 1.91. Each side implies 52.36%, and together they make 104.71%. The extra 4.71% is the margin of the bookmaker, the same idea as the house edge in a casino game.
So an implied chance is always a little too high. What bookmaker margin is shows how to take it out, and the margin calculator does it for any market.
Questions about reading odds
Which odds format is the easiest to compare?
Decimal. The bigger number always returns more, and the implied chance is simply one divided by it.
What does a minus sign in American odds mean?
That the outcome is the favourite. The number is the stake needed for a profit of 100, so −200 asks for 200.
Is the implied probability the real chance?
No. It is the view of the bookmaker with the margin added on top, so the implied chances of all outcomes sum to more than a whole.
How do I turn a fraction into a decimal price?
Divide the top number by the bottom one and add one. For 3/2 that gives 2.50.
Tools for converting and checking a price
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