Odds Converter

The four ways to write odds

Every price says the same thing — how much you win and how likely the outcome is — just in a different dialect:

• Decimal (2.50) — the standard in Australia and Europe. Your total return per $1 staked, stake included. Bet $10 at 2.50 and you get $25 back.
• American (+150 / −200) — common in the US. A positive number is the profit on a $100 stake; a negative number is the stake needed to win $100.
• Fractional (3/2) — traditional UK racing format. The profit relative to the stake: 3/2 means win $3 for every $2 staked.
• Implied probability (40%) — the chance the price suggests, before any bookmaker margin.

How implied probability works

Implied probability is the most useful number of the four because it tells you what the odds actually mean. For decimal odds it is simply 1 ÷ decimal odds: a price of 2.50 implies 1 ÷ 2.50 = 40%. The shorter the price, the higher the implied chance.

Add up the implied probability of every outcome in a market and you’ll get more than 100% — the excess is the bookmaker’s margin. Stripping it out is what our No-Vig Fair Odds tool does, and comparing it to the true chance is the job of the EV Calculator.

Why it matters

Reading a price fluently is the first skill of a disciplined bettor. Once odds and probability are interchangeable in your head, spotting a mispriced bet — or a better price at another book — becomes second nature.