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Odds Converter and Implied Probability Calculator
Type a price in any format and get the rest: American, decimal, fractional, the implied probability, and what a $100 stake wins. The implied probability is also the break-even win rate the price needs, which is the number every bet should be judged against.
Read as American odds.
Implied probability includes the book's margin. To see what the market really thinks, put both sides of the line into the no-vig calculator.
How the math works
Decimal odds are the payout per dollar staked, stake included, and every other format is a way of writing the same number. Convert to decimal first and the rest falls out:
positive American +A: decimal = 1 + A ÷ 100 · negative American −A: decimal = 1 + 100 ÷ A
implied probability = 1 ÷ decimal · fractional = (decimal − 1), written as a fraction
Worked example: −110 is 1 + 100 ÷ 110 = 1.909 decimal. One divided by 1.909 is52.4%, so a −110 bet has to win 52.4% of the time just to break even, not 50%. That gap is the vig, and it is why −110 is not a 50/50 bet. The two sides of any line add up to more than 100% for the same reason; the no-vig calculator removes that margin and gives the fair price.
Common prices
| American | Decimal | Fractional | Implied probability | $100 wins |
|---|---|---|---|---|
| -300 | 1.33 | 1/3 | 75.0% | $33 |
| -200 | 1.50 | 1/2 | 66.7% | $50 |
| -150 | 1.67 | 2/3 | 60.0% | $67 |
| -110 | 1.91 | 10/11 | 52.4% | $91 |
| +100 | 2.00 | 1/1 | 50.0% | $100 |
| +120 | 2.20 | 6/5 | 45.5% | $120 |
| +150 | 2.50 | 3/2 | 40.0% | $150 |
| +200 | 3.00 | 2/1 | 33.3% | $200 |
| +300 | 4.00 | 3/1 | 25.0% | $300 |
| +500 | 6.00 | 5/1 | 16.7% | $500 |
Odds questions
What is implied probability?
The win rate a price needs to break even. Divide one by the decimal odds: −110 is 1.909 decimal, so 52.4%. It includes the book's margin, so both sides of a line add up to more than 100%.
How do I convert American odds to decimal?
A plus price pays its number per $100: +150 is 1 + 150 ÷ 100 = 2.50. A minus price makes you risk its number to win $100: −150 is 1 + 100 ÷ 150 = 1.67. Fractional odds are the decimal minus one, so +150 is 3/2.
Why do the two sides of a bet add up to more than 100%?
Because the book keeps a margin. At −110 each side implies 52.4%, so the pair sums to 104.8% and the extra 4.8% is the vig. Strip it out with the no-vig calculator and you have the market's honest estimate, which is the price every bet should be compared with. How to devig odds walks through it.
Which format should I use?
They are the same bet written three ways. Decimal is easiest for math and for parlays, American is what the US books show, and fractional is the UK habit. Whatever you read, judge the bet by the implied probability, because that is the number you have to beat. What +EV betting means starts from there.
Want the prices judged for you every morning?
The Lab converts, devigs and compares every prop on the board across every book quoting it, and shows the work.