Odds Converter: American, Decimal and Fractional
American odds show the profit on a $100 bet when positive and the stake needed to win $100 when negative. Decimal odds show the total return per $1 staked, and fractional odds show profit relative to stake. All three describe the same price and convert exactly.
Key facts
- American odds of +150 equal decimal 2.50 and fractional 3/2.
- Decimal odds = total return per unit staked, including the stake (Wikipedia, Decimal odds).
- Implied probability = 1 ÷ decimal odds.
Sportsbooks quote the same price three different ways. This converter takes any of them and shows the other two, the win chance the price implies, and the payout on whatever stake you choose. It runs in your browser, sends nothing anywhere and forgets your numbers when you close the page.
Odds converter
Turn on JavaScript to use the calculator. The worked example below shows the same math by hand.
What you enter and what you get
You enter
- Odds: Type -110, +150, 2.5 or 3/2.
- Stake ($) (optional): Default is $100.
You get
- Implied probability
- American
- Decimal
- Fractional
- Profit on your stake
- Total back on your stake
How the calculator works
- Positive American odds: decimal = 1 + odds ÷ 100.
- Negative American odds: decimal = 1 + 100 ÷ |odds|.
- Fractional odds a/b: decimal = 1 + a ÷ b.
- Implied probability is 1 ÷ decimal odds.
A worked example
Odds of +150 on a $100 stake.
| Item | Result |
|---|---|
| Implied probability | 40% |
| American | +150 |
| Decimal | 2.5 |
| Fractional | 3/2 |
| Implied probability | 40% |
| Profit on $100 | $150 |
| Total back on $100 | $250 |
What the calculator leaves out
- Fractions are shown as the closest simple fraction, so some prices round.
- It converts a price; it doesn't say whether the price is fair.
- Plain whole numbers of 100 or more are read as American odds.
How we checked it
Before it went on the page we checked it against values worked by hand: -110 has to come out at an implied probability of 52.38%, and the same price typed as American, decimal or fractional has to give the same answer. The calculator is also run against thousands of odd entries such as blanks, zeros and huge numbers, so a bad entry shows a plain prompt and never a wrong number. The worked example above comes from the same code the calculator runs.
At a sweepstakes sportsbook
Sweepstakes sportsbooks show odds in whichever format they choose, and the conversion is identical. The part to check is what a payout in the site's coins is worth under its rules, which Gold Coins vs Sweeps Coins explains.
Betting math is not betting advice. Only play with money you can afford to lose, and if gambling stops being fun, call or text 1-800-GAMBLER.
Frequently asked questions
What does -110 mean?
You risk $110 to win $100. In decimal that is 1.909, and the implied win chance is 52.38%.
What does +150 mean?
A $100 bet wins $150 in profit. In decimal that is 2.50, and the implied chance is 40%.
Which format is best?
Decimal is the easiest for math, American is common in US sportsbooks and fractional is common in the UK.
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- Odds, Wikipedia (read 2026-10-05)
- Decimal odds, Wikipedia (read 2026-10-05)
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