This odds converter switches a price between decimal, fractional and American odds, and shows the implied probability: the chance of the outcome that the price suggests.
Whatever format a bookmaker uses, you can read every price the same way.
Odds converter
Key points
- Decimal odds include your stake, so 4.50 returns £4.50 for every £1.
- Fractional a/b becomes a/b + 1 in decimal.
- Implied probability = 1 ÷ decimal odds.
Using the converter
Type a price into any one box, decimal, fractional or American, and the converter fills in the other two formats plus the implied percentage.
For American odds, use a plus sign for prices bigger than evens, such as +350, and a minus sign for favourites, such as −250.
Worked example
Worked example
Take a price of 7/2. In decimal that is 7 ÷ 2 + 1 = 4.50, and in American odds it is +350, because a £100 stake would win £350.
The implied chance is 1 ÷ 4.50 = 22.2%.
Now try Arsenal at 2/5 at home to Leeds. That is 2 ÷ 5 + 1 = 1.40 in decimal, or −250 in American odds, because you stake £250 to win £100. The implied chance is 1 ÷ 1.40 = 71.4%.
Reading the results
The implied percentage is the chance at which the price would be fair, not the true chance. Bookmakers build in a margin, so the implied percentages across a market always add up to more than 100%. Our implied probability guide explains this in full.
If you believe the real chance is higher than the implied percentage, the price may be value, though that is only your estimate. To strip out the margin, use the fair odds calculator, and to compare a price with your own view, try the expected value calculator.
Why convert odds at all?
Many UK sites show fractions, while exchanges and most tools use decimals, and US sources quote American odds. Converting puts them all on one scale so you can compare like with like. For background on the formats, see the Wikipedia article on odds.
Related guides and calculators
- Implied probability: what betting odds really say
- Fair odds and bookmaker margins
- All betting calculators
18+ only. Betting should stay fun. Set a budget before you start, only bet what you can comfortably afford, and take a break whenever you need one. For free, confidential support, visit BeGambleAware.org or call the National Gambling Helpline on 0808 8020 133.