Odds Converter Calculator
Convert betting odds between decimal, fractional and American formats and instantly see the implied probability.
Odds converter inputs
How to use the odds converter
This free odds converter allows you to enter decimal, fractional or American odds and instantly translate the price into the other major formats. It also calculates the implied probability and the theoretical profit on a 100-unit stake.
Select the format you want to enter, type the odds and press Convert odds. The calculator converts the price without changing its mathematical value.
What are decimal odds?
Decimal odds show the total return per unit staked, including the original stake. Decimal odds of 2.50 mean that a 100-unit stake would return 250 units in total: 150 units of profit plus the original 100-unit stake.
Stake × Decimal oddsDecimal odds are widely used in Europe and are usually the easiest format for accumulator calculations because prices can be multiplied directly.
What are fractional odds?
Fractional odds show net profit relative to stake. Odds of 3/2 mean three units of profit for every two units staked. A two-unit stake would therefore return five units in total: three units of profit plus the two-unit stake.
(Numerator ÷ Denominator) + 1Fractional odds remain common in the United Kingdom and Ireland. The converter accepts formats such as 3/2, 5/4, 10/11 and 1/1.
What are American odds?
American odds use positive and negative numbers. Positive odds show how much profit a 100-unit stake would produce. For example, +150 means 150 units of profit from a 100-unit stake.
Negative odds show how much must be staked to win 100 units. For example, -200 means a 200-unit stake is required to make 100 units of profit.
(American ÷ 100) + 1(100 ÷ |American|) + 1What is implied probability?
Implied probability converts the market price into a percentage. For decimal odds, the basic formula is:
100 ÷ Decimal oddsDecimal odds of 2.50 imply a probability of 40%. This is a price-based figure and does not automatically represent the true probability because bookmaker margin may be included.
Odds conversion formulas
| Conversion | Formula |
|---|---|
| Decimal to fractional | Decimal odds − 1, then express as a fraction |
| Decimal to American, decimal ≥ 2.00 | (Decimal − 1) × 100 |
| Decimal to American, decimal < 2.00 | −100 ÷ (Decimal − 1) |
| Fractional to decimal | (Numerator ÷ Denominator) + 1 |
| Positive American to decimal | (American ÷ 100) + 1 |
| Negative American to decimal | (100 ÷ |American|) + 1 |
Odds conversion examples
| Decimal | Fractional | American | Implied probability | Profit per 100 |
|---|---|---|---|---|
| 1.50 | 1/2 | -200 | 66.67% | 50 |
| 2.00 | 1/1 | +100 | 50.00% | 100 |
| 2.50 | 3/2 | +150 | 40.00% | 150 |
| 3.00 | 2/1 | +200 | 33.33% | 200 |
| 1.91 | 10/11 | -110 | 52.36% | 91 |
Example 1: decimal to fractional
Decimal odds of 2.50 become 3/2 fractional odds because 2.50 minus 1 equals 1.50, which simplifies to 3/2.
Example 2: decimal to American
Because 2.50 is greater than 2.00, subtract 1 and multiply by 100. The result is +150.
Example 3: negative American odds
American odds of -200 convert to decimal odds of 1.50. A 200-unit stake would make 100 units of profit.
Why odds format does not change value
Decimal, fractional and American odds are different ways of expressing the same underlying price. Converting 2.50 into 3/2 or +150 does not improve or reduce the value of the bet. Only the presentation changes.
Common odds conversion mistakes
- Confusing return with profit. Decimal odds include the returned stake, while fractional odds focus on profit.
- Removing the plus or minus sign from American odds. +150 and -150 represent very different prices.
- Entering fractional odds as a decimal. 3/2 must be entered as a fraction, not as 1.5 in fractional mode.
- Assuming implied probability is fair probability. Bookmaker margin may be included.
- Rounding too early. Rounding can create small differences between formats.
- Comparing prices in different formats without converting them first.
Odds conversion and bookmaker margin
Converting a single price does not remove bookmaker margin. To estimate a no-vig market, you need the odds for every possible outcome and must normalise the total implied probability back to 100%.
Related odds and probability guides
Convert the price, then understand what it means
Odds format is only presentation. Explore the Academy for implied probability, value, margin and bankroll-management guidance.
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Odds Converter FAQ
What is an odds converter?
An odds converter translates the same betting price between decimal, fractional and American formats.
Which odds format is best?
No format is mathematically superior. Decimal odds are usually easiest for return and accumulator calculations.
Does converting odds change the value?
No. The underlying betting price remains the same.
How do I convert decimal odds to fractional?
Subtract 1 from the decimal price and express the result as a fraction.
How do I convert fractional odds to decimal?
Divide the numerator by the denominator and add 1.
How do I convert positive American odds to decimal?
Divide the American odds by 100 and add 1.
How do I convert negative American odds to decimal?
Divide 100 by the absolute American odds and add 1.
What does +150 mean?
It means a 100-unit stake would produce 150 units of profit.
What does -200 mean?
It means a 200-unit stake is required to make 100 units of profit.
Why is the fractional result approximate?
Some decimal prices do not convert into a simple fraction, so the calculator uses a close rational representation.
What is implied probability?
It is the probability represented by the odds, calculated from the converted decimal price.
Does implied probability include bookmaker margin?
A single quoted price may include margin. Removing margin requires all outcomes in the market.
Can I enter fractional odds such as 10/11?
Yes. Select Fractional and enter the price in numerator/denominator format.
Can I enter positive and negative American odds?
Yes. Select American and include the plus or minus sign.
Is my data stored?
No. The conversion runs locally in your browser and requires no registration.