Odds converter
Type into any box — fractional, decimal, American or implied probability — and the others update instantly.
How odds formats work
Fractional odds (5/2) show profit against stake: win £5 for every £2. Decimal odds (3.50) show the total return per £1, stake included — the format betting exchanges and most of our tools use. American odds show profit on £100 (+250) or the stake needed to win £100 (−150). Implied probability is 1 divided by the decimal odds: the chance the price says the outcome has, before the bookmaker's margin comes out.
Implied probability is the one to watch. Add up the implied chances for every outcome in a market and you'll get more than 100% — the excess is the bookmaker's margin. Measure it with our margin calculator →
Questions
How do I convert fractional odds to decimal?
Divide the first number by the second and add 1. So 5/2 is 2.5 + 1 = 3.50, and evens (1/1) is 2.00.
How do I turn odds into a probability?
Divide 1 by the decimal odds. Odds of 4.00 imply a 25% chance; 1.50 implies 66.7%.
More free tools
- Bet builder calculator — Work out the fair odds of any bet builder and see whether your bookmaker's price is value.
- Bookmaker margin calculator — See how much margin is built into a market, and the fair odds once it's taken out.
- Value bet calculator — Compare a bookmaker's price with the fair price and see the edge and expected profit.
- Arbitrage calculator — Two or three outcomes, back or lay: exact stakes for a guaranteed profit.