Odds converter
Every odds format is the same number wearing a different coat: a probability. Convert between decimal, fractional, American and implied percentage instantly — then strip out the bookmaker's margin to see what the market really thinks.
Fair probabilities use the multiplicative method — the standard first-order de-vig. Sharper methods exist for longshot-heavy markets; for two- and three-way markets this is the one to use.
Convert odds
Type into any format — the rest follow.
Odds of 2.50 mean the book prices this outcome at 40.0% — a fair bet only if you think the true chance is higher.
Remove the vig
Enter every outcome of one market (decimal odds) to see the bookmaker's margin and the fair probabilities underneath it.
This book runs a 4.7% margin — the implied probabilities total 104.7%.
| Implied | Fair | Fair odds | |
|---|---|---|---|
| A | 52.4% | 50.0% | 2.00 |
| B | 52.4% | 50.0% | 2.00 |
Frequently Asked Questions
How do I convert odds to a percentage?
Divide 1 by the decimal odds and multiply by 100. Decimal odds of 2.50 imply 1 ÷ 2.50 = 40%. For fractional odds, convert to decimal first (add 1 to profit ÷ stake); for American odds, +150 means 100 ÷ (150 + 100) = 40%, and -200 means 200 ÷ (200 + 100) = 66.7%.
What is implied probability?
The chance of an outcome that a price implies. Odds of 2.50 imply 40% — if you believe the true chance is above 40%, the price is value; below it, the price is against you. Prediction market prices are implied probabilities stated directly: a contract at 40¢ is the market saying 40%.
Why do the implied probabilities add up to more than 100%?
That excess is the bookmaker's margin — the vig or overround. A coin-flip market priced at 1.91/1.91 implies 52.4% + 52.4% = 104.8%; the 4.8 points above 100 are the book's edge. The fair probabilities are what remains after normalising that margin away.
Which odds format do New Zealand casinos and bookmakers use?
Decimal, as across most of Europe and Australia. Fractional odds persist in the UK and Ireland, and American odds (+150/-200) dominate US books and are increasingly common on crypto sportsbooks and prediction markets serving international players.