- Pick the format of the odds you have and enter the value.
- Read the equivalent in American, Decimal, Fractional, Probability, and Contract formats.
Odds Converter
An odds converter for American, decimal, and fractional sports betting odds. Convert between formats and see the implied probability for any line.
How to Use This Calculator
What is an odds converter?
An odds converter translates sports betting odds between three formats: American, decimal, and fractional. The same bet can be quoted as -110, 1.91, or 10/11, and the math underneath is identical. The format affects how the number is read but not what it represents.
American odds
The default format in US sportsbooks. Positive numbers (+100, +200) show how much profit a $100 bet returns. Negative numbers (-110, -200) show how much needs to be bet to win $100.
Decimal odds
The default format in most of Europe and Australia. A decimal of 2.00 means a $1 bet returns $2 total (including the original stake). Decimal odds multiply cleanly, which makes them the standard format for parlay math.
Fractional odds
Common in the UK and Ireland. Expressed as a ratio (10/11, 5/2, 1/2). The fraction represents profit over stake. 5/2 means a $2 bet returns $5 in profit plus the $2 stake.
Worked example
A standard moneyline at -110 American odds converts across formats as follows.
\[
\begin{aligned}
\text{Decimal} &= \dfrac{\strut 100}{\strut 110} + 1 = 1.91 \\[6pt]
\text{Fractional} &= \dfrac{\strut 10}{\strut 11} \\[6pt]
\text{Implied Probability} &= \dfrac{\strut 110}{\strut 210} \approx 52.38\%
\end{aligned}
\]
All four representations describe the same bet at the same price.
Why odds conversion matters for sports bettors
Different sportsbooks default to different formats, and different calculations are easier in different formats. American odds are how most US bets are displayed. Decimal odds are how parlays multiply cleanly. Implied probability is how expected value is calculated. Fluent bettors switch between formats as needed.
For a complete walkthrough of how sportsbook odds work, read our How to Read Sportsbooks Odds guide. Pair this converter with the Implied Probability Calculator to see the win percentage behind any odds.
Common mistakes
- Confusing +100 and 2.00. They are the same price (even money). +100 American equals 2.00 decimal.
- Forgetting to add 1 when converting decimal to fractional. Decimal 2.50 is 3/2 fractional, not 2.50/1. The stake is included in the decimal number but not in the fractional.
- Reversing the favorite formula. Negative American odds get larger in magnitude as the favorite gets heavier (-110 is barely favored, -500 is a heavy favorite). Decimal odds get smaller in the same direction (1.91 versus 1.20).
- Treating implied probability as a percentage with no vig. The implied probability from any single odds includes the vig. The no-vig probability requires looking at both sides of a market.
Frequently Asked Questions
What is an odds converter?
An odds converter translates sports betting odds between American, decimal, and fractional formats. Enter the odds in any one format and the calculator returns the equivalent in all three, plus the implied probability.
How do I convert American odds to decimal?
For positive American odds, divide the odds by 100 and add 1. For negative American odds, divide 100 by the absolute value of the odds and add 1.
\[
\begin{aligned}
\text{Decimal (positive odds)} &= \dfrac{\strut \text{American}}{\strut 100} + 1 \\[6pt]
\text{Decimal (negative odds)} &= \dfrac{\strut 100}{\strut -\text{American}} + 1
\end{aligned}
\]
So +150 is 2.50 decimal, and -150 is 1.67 decimal.
How do I convert decimal odds to American?
For decimal odds 2.00 or higher, subtract 1 and multiply by 100. For decimal odds below 2.00, divide -100 by the decimal minus 1.
\[
\begin{aligned}
\text{American (decimal} \geq 2.00) &= (\text{Decimal} - 1) \times 100 \\[6pt]
\text{American (decimal} < 2.00) &= \dfrac{\strut -100}{\strut (\text{Decimal} - 1)}
\end{aligned}
\]
So 2.50 decimal is +150 American, and 1.67 decimal is approximately -150 American.
How do I read fractional odds?
Read the numerator as profit and the denominator as stake. 7/2 means a $2 bet returns $7 in profit (plus the $2 stake back). 1/3 means a $3 bet returns $1 in profit (plus the $3 stake back).
Which odds format is the most accurate?
All three formats represent the same underlying probability. None is more accurate. They differ only in presentation.
Should I always work in decimal odds?
For parlay math and quick comparisons, decimal odds are easier because they multiply cleanly. For evaluating expected value, implied probability is cleanest. For reading US sportsbook displays, American is necessary. Use the format that fits the task.
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