Odds Converter — American, Decimal and Fractional Odds
Type a price in American, decimal or fractional odds and see it in the other two formats, with the implied probability and the payout on your stake.
Type a price in any box — the other formats update as you type.
e.g. -110 or +150 · your saved format
e.g. 1.91 or 2.50
e.g. 10/11 or 6/4
Profit and payout are priced on this stake
Implied Probability
52.38%
Profit on a $100.00 stake
$90.91
Total payout on $100.00
$190.91
Break-even: the bet must win more than 52.38% of the time to profit. Implied probability includes the bookmaker's margin.
Last reviewed · How we check our calculators
How it differs: this calculator translates a price between American, decimal and fractional odds. To see what a stake pays at that price, use the Betting Odds Calculator.
How to Use the Odds Converter
The converter has three boxes — American, Decimal and Fractional. Type a price into whichever box matches the odds you were quoted and the other two update as you type. There is no need to pick a direction first: the box you typed in is the source, and the rest are worked out from it.
- American odds (moneyline) — enter a negative number for a favourite such as -110 and a positive number for an underdog such as +150. The plus sign is optional.
- Decimal odds — enter the total return per unit staked, such as 1.91 or 2.50.
- Fractional odds — enter profit over stake with a slash, such as 5/2 or 10/11. "Evens" works too.
Under the boxes you get the implied probability — the win rate the price assumes, which is also the break-even win rate for the bet — and the profit and total payout on your stake: $100 until you change it, and the stake you set is remembered on this device like the odds format.
The box for your saved odds format comes first and holds the starting price. The format is the one you picked on any CalcVault betting calculator, so the converter opens in the format you bet in. Use Share results to copy a link that reopens the converter with the exact price you typed.
The Formula
Every conversion goes through decimal odds, the total return per 1 staked. Write D for decimal odds, A for American odds and n/d for fractional odds.
American → decimal
- Positive A: D = A ÷ 100 + 1 (+150 → 2.50)
- Negative A: D = 100 ÷ |A| + 1 (-110 → 1.909…)
Decimal → American
- D ≥ 2.00: A = (D − 1) × 100 (3.40 → +240)
- D below 2.00: A = −100 ÷ (D − 1) (1.65 → −153.8, shown as -154)
Fractional ⇄ decimal
D = n ÷ d + 1, so 5/2 is 3.50. Going the other way, D − 1 is the profit per unit, which is turned into the fraction a bookmaker would quote.
Implied probability
Implied probability = 1 ÷ D × 100%. At -110 that is 1 ÷ 1.909 = 52.38%.
Why the numbers do not drift
A typed price carries a precision. -110 stands for anything that rounds to -110, and 1.91 for anything from 1.905 up to 1.915. Converting naively and rounding at each step makes prices creep: 1.91 becomes -109.89, and 8/13 becomes 1.62 and then 13/21. This converter does two things instead:
- Each converted figure is the shortest one that converts back to the price you typed. -110 shows as 1.91 because 1.91 converts back to -110. -300 shows as 1.333, because 1.33 would convert back to -303.
- The fraction is the bookmaker price inside the range the typed price stands for, when there is one (1.91 → 10/11, 1.83 → 5/6, 1.01 → 1/100); otherwise an exact fraction (-115 is 20/23) or the simplest fraction inside the range, found with the Stern–Brocot method.
So -110 → 1.91 → -110, 10/11 → -110 → 10/11 and 1.62 → 8/13 → 1.62, however many times you switch boxes. The implied probability and payout always use the exact price, never a rounded figure.
Practical Examples
Example 1 — NFL spread at -110
A US sportsbook prices both sides of a spread at -110. Typed into the American box:
- Decimal: 1.91 · Fractional: 10/11
- Implied probability: 52.38%
- Profit on $100: $90.91 · Total payout: $190.91
To break even at -110 you have to win more than 52.38% of these bets. Both sides together imply 104.76%, and the 4.76 points over 100% are the bookmaker's margin.
Example 2 — Horse at 5/2
A UK bookmaker offers a horse at 5/2. Typed into the fractional box:
- American: +250 · Decimal: 3.50
- Implied probability: 28.57%
- Profit on $100: $250.00
Example 3 — Exchange price of 1.65
A betting exchange shows 1.65. Typed into the decimal box:
- American: -154 · Fractional: 13/20
- Implied probability: 60.61%
- Profit on $100: $65.00
Example 4 — +333 and 100/30
+333 converts to decimal 4.33 and fractional 10/3, which UK books write as 100/30. The implied probability is 23.09%.
Conversion chart
Common lines in all three formats, converted by the same code as the calculator above.
| American | Decimal | Fractional | Implied probability |
|---|---|---|---|
| -500 | 1.20 | 1/5 | 83.33% |
| -300 | 1.333 | 1/3 | 75.00% |
| -200 | 1.50 | 1/2 | 66.67% |
| -150 | 1.667 | 2/3 | 60.00% |
| -120 | 1.83 | 5/6 | 54.55% |
| -110 | 1.91 | 10/11 | 52.38% |
| -105 | 1.95 | 20/21 | 51.22% |
| +100 | 2.00 | 1/1 | 50.00% |
| +120 | 2.20 | 6/5 | 45.45% |
| +150 | 2.50 | 3/2 | 40.00% |
| +200 | 3.00 | 2/1 | 33.33% |
| +250 | 3.50 | 5/2 | 28.57% |
| +300 | 4.00 | 3/1 | 25.00% |
| +500 | 6.00 | 5/1 | 16.67% |
| +1000 | 11.00 | 10/1 | 9.09% |
To see what a stake pays at any of these prices, use the Betting Odds Calculator. To remove the bookmaker's margin from a pair of prices, use the No-Vig Calculator.
Frequently Asked Questions
For positive American odds, divide by 100 and add 1: +150 becomes 2.50. For negative American odds, divide 100 by the odds without the minus sign and add 1: -110 becomes 100 ÷ 110 + 1 = 1.909, shown as 1.91. Decimal odds always include your stake.
If the fraction is 1/1 or longer, multiply it by 100: 5/2 is +250. If it is shorter than evens, divide −100 by the fraction: 10/11 is −100 ÷ (10/11) = -110. Evens (1/1) is +100.
Because 1.91 converts back to -110, so the extra digit adds nothing. The converter shows the shortest figure that converts back to the price you typed. When two decimals are not enough, as with -300 (1.333), it shows three or more.
It is the win rate the odds assume: 1 divided by the decimal odds. At 2.50 it is 40%. If you think the real chance is higher than the implied probability, the price is value. Remember that a bookmaker's prices carry a margin, so the implied probabilities of all outcomes add up to more than 100%.
Use whatever your sportsbook shows. US books quote American odds, European, Australian and exchange sites quote decimal, and UK and Irish horse racing quotes fractional. The price is the same in all three formats, so the payout is identical. Decimal odds are the easiest to compare and to multiply in parlays.
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