▌ Calculator · odds converter · updated 2026-05-09
American, decimal, fractional, implied probability — four ways to express the same number. Sportsbooks in the US show moneylines. European sites use decimal. UK bookmakers use fractions. Exchanges show implied probability. Switching between them manually means errors. This converter does it instantly.
Enter any format and all four update live. Works for underdogs (+200), heavy favorites (-800), even money (+100 / 2.00 / 1/1 / 50%), and everything between. Shareable URL syncs with each entry. After converting, use the payout calculator to see your returns or the implied probability calculator to detect edge.
▌ Input format
Enter any format above. All four representations update live.
▌ All formats
American
-110
Decimal
1.91
Fractional
10/11
Implied probability
52.38%
▌ Derivation · conversion formulas
All formats represent the same probability. Decimal odds are the base unit — the cleanest form because they directly express payout-per-unit-staked including stake return. Every other format converts through decimal.
Positive moneyline (underdog): decimal = american / 100 + 1.
At +200: 200 / 100 + 1 = 3.00.
Negative moneyline (favorite): decimal = 100 / |american| + 1.
At -150: 100 / 150 + 1 = 1.667.
Reverse (decimal → American): if decimal ≥ 2,
american = (decimal − 1) × 100 (positive).
If decimal < 2, american = −100 / (decimal − 1) (negative).
Fractional odds express profit per unit staked. 5/1 means
$5 profit on $1 staked. To convert to decimal:
decimal = numerator / denominator + 1. So
5/1 → 5/1 + 1 = 6.0. And
10/11 → 10/11 + 1 = 1.909.
Reverse (decimal → fractional): subtract 1 to get the fraction value, then find the nearest simple ratio with denominator ≤ 100. This is why the converter sometimes rounds fractional odds slightly — UK bookmakers do the same.
probability = 1 / decimal × 100%. At 1.909 decimal:
1 / 1.909 × 100 = 52.38%. Reverse:
decimal = 1 / (probability / 100). At 40%:
1 / 0.40 = 2.50.
Implied probability is the bookmaker's embedded estimate of that outcome's chance of occurring — inflated by the vig. Strip the vig with the no-vig calculator to find the true probability the market implies.
| American | Decimal | Fractional | Prob |
|---|---|---|---|
| +500 | 6.00 | 5/1 | 16.67% |
| +200 | 3.00 | 2/1 | 33.33% |
| +150 | 2.50 | 3/2 | 40.00% |
| +110 | 2.10 | 11/10 | 47.62% |
| −110 | 1.909 | 10/11 | 52.38% |
| −150 | 1.667 | 2/3 | 60.00% |
| −200 | 1.500 | 1/2 | 66.67% |
| −400 | 1.250 | 1/4 | 80.00% |
▌ Worked example
-300 (heavy favorite — betting favorite to win) 100 / 300 + 1 = 0.333 + 1 = 1.333 1.333 − 1 = 0.333 = 1/3 1 / 1.333 × 100 = 75.00% The book implies a 75% win chance. A $300 bet wins $100 profit ($400 total). ▌ Format guide
DraftKings, FanDuel, BetMGM, Caesars, PointsBet — all display moneylines in American format. The minus sign shows favorites (stake to win $100); the plus shows underdogs (profit on $100). Negative odds are never less than -101.
Bet365, Unibet, William Hill (UK), Betway, Pinnacle default to decimal. Multiply your stake by the decimal to get total return. 2.00 is even money. Below 2.0 means the outcome is favored; above 2.0 is underdog territory. Simplest format for payout calculations.
Horse racing, football pools, and UK betting shops traditionally use fractionals. The ratio shows profit relative to stake — 5/2 means $5 profit per $2 staked ($7 total). "Evens" (1/1) is the equivalent of +100 American or 2.00 decimal.
Useful for comparing across books or against your own model. Odds are meaningless without a probability comparison — if you think Team A wins 60% of the time but the book offers 50% implied probability, you have 10% edge. Use the implied probability calculator to convert any line to a percentage directly.
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