Odds Calculator
Convert betting odds between American, decimal and fractional formats, see the implied probability, payout and profit for any stake, and enter the other side of the market to measure the bookmaker margin (vig) and find fair no-vig odds. Example: -110 on both sides is 52.38% each, a 4.76% margin, and true odds of 50/50.
Show steps
How to use the Odds Calculator
- Pick the odds format and type the odds for your side.
- To see the bookmaker margin, enter the odds for the other side of the same market in the same format.
- Enter your stake and press Calculate for payout, profit, implied probability and fair odds.
Formula and method
Decimal odds from American: positive a gives 1 + a/100; negative a gives 1 + 100/|a|. Fractional n/d gives 1 + n/d. Implied probability = 1 / decimal odds. Profit = stake x (decimal – 1). Margin = sum of implied probabilities – 1. No-vig probability = implied probability / sum of implied probabilities.
Odds conversion cheat sheet
| American | Decimal | Fractional | Implied probability |
|---|---|---|---|
| -200 | 1.50 | 1/2 | 66.67% |
| -110 | 1.91 | 10/11 | 52.38% |
| +100 | 2.00 | 1/1 | 50.00% |
| +150 | 2.50 | 3/2 | 40.00% |
| +250 | 3.50 | 5/2 | 28.57% |
| +400 | 5.00 | 4/1 | 20.00% |
| +1000 | 11.00 | 10/1 | 9.09% |
Worked example: -110 on both sides
| Step | Result |
|---|---|
| Decimal odds | 1.9091 |
| Implied probability each side | 52.38% |
| Total of both sides | 104.76% |
| Bookmaker margin | 4.76% |
| No-vig probability | 50.00% each |
| Profit on a $100 stake | $90.91 |
What the margin means
A fair coin-flip market would pay +100 on each side. At -110 on both sides you must win 52.38% of the time just to break even, and the 4.76% margin is the bookmaker’s built-in edge.
Odds formats by region
American odds are common in the United States, decimal odds in Europe, Canada and Australia, and fractional odds in the United Kingdom and Ireland. They all describe the same price.
Frequently asked questions
How do I convert American odds to decimal?
For positive odds, divide by 100 and add 1. For negative odds, divide 100 by the absolute value and add 1.
What does -110 mean?
You must stake $110 to win $100 profit, which is decimal 1.91 and an implied probability of 52.38%.
What is implied probability?
The chance the odds suggest, equal to 1 divided by the decimal odds.
What is the vig or overround?
The bookmaker margin: the amount by which the implied probabilities of all outcomes add to more than 100%.
What are no-vig or fair odds?
The odds you would see if the margin were removed, found by scaling each implied probability so they total 100%.
Does a high implied probability mean a bet is good?
No. Value exists only when your own estimate of the true probability beats the implied probability.
Sources
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