Odds Converter
Convert between American, Decimal, and Fractional odds; plus see the implied probability for any line. All math runs in your browser; nothing is sent or stored.
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Odds formats in plain English
Every odds format describes the same thing; how much you win per dollar staked; but expresses it differently. Once you can read all three formats fluently, line-shopping across multiple sportsbooks (some of which display in decimal by default) becomes much faster.
American (US default)
American odds use a + or − prefix with a number based on $100. A positive number shows profit on a $100 bet (so +150 means a $100 bet wins $150 profit). A negative number shows the stake required to win $100 (so -180 means you stake $180 to win $100). The +/− tells you immediately who is favored.
Decimal (European standard)
Decimal odds represent your total return per dollar staked, including the stake. A bet at 2.50 returns $250 for every $100 staked: $150 profit plus the $100 stake back. Decimal is cleaner for math because computing payout is just stake × decimal odds. Most serious bettors track lines in decimal even when their sportsbook displays American.
Fractional (UK standard)
Fractional odds (3/2, 5/1, 9/4) show profit-to-stake ratio. A bet at 3/2 wins $3 profit for every $2 staked; equivalent to American +150 or decimal 2.50. UK bookmakers and traditional horse-racing books default to this format.
Implied probability
Implied probability is the win probability that the price suggests. American +150 = 40.0% implied probability (100 / (150 + 100)); American -180 = 64.3% implied probability (180 / (180 + 100)); decimal 2.50 = 40.0% (1 / 2.50). When you sum implied probabilities across both sides of a market, the total exceeds 100% by the operator's hold percentage. Two sides at -110 each = 52.38% + 52.38% = 104.76%, meaning the hold is 4.76%. To strip the hold and see the fair-market probability, use our no-vig calculator.
Conversion cheat sheet
| American | Decimal | Fractional | Implied % | Plain English ($100 stake) |
|---|---|---|---|---|
| +300 | 4.00 | 3/1 | 25.0% | Win $300 profit |
| +200 | 3.00 | 2/1 | 33.3% | Win $200 profit |
| +150 | 2.50 | 3/2 | 40.0% | Win $150 profit |
| +100 | 2.00 | 1/1 (evens) | 50.0% | Win $100 profit (double up) |
| -110 | 1.91 | 10/11 | 52.4% | Win $91 profit (standard juice) |
| -150 | 1.67 | 2/3 | 60.0% | Win $67 profit |
| -200 | 1.50 | 1/2 | 66.7% | Win $50 profit |
| -300 | 1.33 | 1/3 | 75.0% | Win $33 profit |
All entries above represent the same payout in different formats. None is "better"; choose the one your brain reads fastest.
Common questions
How do I convert American odds to decimal?
For positive American odds (e.g. +150): decimal = (odds / 100) + 1, so +150 = 2.50. For negative American odds (e.g. -180): decimal = (100 / odds) + 1, so -180 = 1.556. Decimal odds represent the TOTAL return per $1 staked (including your stake back), so a $100 bet at 2.50 returns $250 total ($150 profit + $100 stake).
How do I convert American odds to implied probability?
For positive odds (+150): probability = 100 / (odds + 100), so +150 = 100 / 250 = 40.0%. For negative odds (-180): probability = -odds / (-odds + 100), so -180 = 180 / 280 = 64.3%. Implied probability includes the sportsbook margin; the sum of both sides of a market typically exceeds 100% by the hold percentage.
What is fractional odds (the UK format)?
Fractional odds (e.g. 3/2, 5/1, 9/2) show profit relative to stake. 3/2 means "for every $2 staked, $3 profit"; equivalent to American +150 or decimal 2.50. A $20 bet at 3/2 wins $30 profit ($50 total return). UK bookmakers and horse-racing books default to this format.
Why do US sportsbooks use American odds?
Historical convention dating to early-1900s US bookmaking. The +/- format communicates favorite/underdog status instantly without computation. Decimal odds are more mathematically clean but require an extra step to identify the favorite. Most US-licensed sportsbooks now offer a settings toggle to switch displays to decimal or fractional.
Which format is best?
For computation and probability work: decimal. For instant favorite/underdog identification: American. For traditional horse racing: fractional. Most serious bettors track in decimal (cleanest math) but place bets in whatever format their sportsbook displays. Conversions are lossless; no information is gained or lost between formats.
What is "implied probability" and why does the sum exceed 100%?
Implied probability is the win probability that a sportsbook's odds suggest. When you sum both sides of a two-way market, the total exceeds 100% by the operator's margin (the "vig" or "hold"). For example, two sides priced at -110 each have implied probabilities of 52.38% + 52.38% = 104.76%, meaning the hold is 4.76%. Strip the vig with our no-vig calculator to see the operator's "fair" probability assessment.