Convert odds to implied probability
Implied probability is the percentage represented by a quoted price. It is a property of the odds, not a forecast that the outcome will happen.
Formula and worked example
Implied probability = 1 / Decimal odds
Decimal odds of 2.50 imply a probability of 1 / 2.50 = 0.40, or 40%. Fractional odds of 3/2 and American odds of +150 represent the same price.
Why this is not a no-vig probability
A single implied probability does not reveal the bookmaker margin. You need the prices for every mutually exclusive outcome, add their implied probabilities, then normalise each one against that total. Use the vig calculator for that market-wide calculation.
Limits and responsible use
The result does not predict the outcome and does not account for settlement rules. UK-licensed operators must publish rules covering voids, errors, withdrawals and maximum payouts. See Gambling Commission LCCP 4.2.6.
Set a spending limit before gambling and do not chase losses. Read GambleAware's advice and our responsible gambling guidance.
Related tools and guides
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Frequently asked questions
How do you convert odds to a percentage?
Implied probability = 1 / decimal odds, expressed as a percentage. Decimal odds of 2.50 give 1 / 2.50 = 0.40, or 40%. For moneyline, negative odds use odds / (odds + 100) and positive odds use 100 / (odds + 100).
What does implied probability mean?
It is the chance of an outcome that a price represents. A shorter price implies a higher chance. It reflects what the market is charging, not a guarantee of what will happen.
Why do the probabilities add up to more than 100%?
Because the bookmaker's margin is included in every price. A two-way market at -110 on both sides implies 52.4% twice, or 104.8% in total. The 4.8% above 100% is the margin.
How do I get the true probability instead?
Divide each implied probability by the market total so they sum to 100%. That removes the margin proportionally and gives the fair, or no-vig, probability. The no-vig calculator does this for two to six outcomes.
Sources
- Gambling Commission, LCCP condition 4.2.6. Current code accessed 30 July 2026.
- GambleAware, Advice to consider if you're gambling. Accessed 30 July 2026.