Betting Odds Converter
Convert between decimal, fractional, and American moneyline odds with implied probability and payout calculation.
Did this tool work for you?
How to use this calculator
All odds are converted through decimal format as a common base. Implied probability is the inverse of decimal odds expressed as a percentage.
- 1
Select the odds format your sportsbook displays.
- 2
Enter the odds value (e.g. 2.50, 3/2, or +150).
- 3
Enter your stake amount.
- 4
Read the converted odds in all three formats, the implied probability, and your potential payout.
Frequently asked questions
How does the converter move between odds formats?
This tool turns whatever you enter into decimal odds first. Fractional a/b becomes a ÷ b + 1. American +N becomes N ÷ 100 + 1, and American −N becomes 100 ÷ N + 1. The other two formats and the implied probability are then calculated from that decimal figure.
How is implied probability calculated?
As 1 ÷ decimal odds, shown as a percentage to one decimal. Decimal 2.50 gives 40.0% and decimal 1.50 gives 66.7%. It is the arithmetic inverse of the price. It is not a prediction and it does not remove a bookmaker’s margin.
How are the American and fractional results produced?
For decimal odds of 2.00 or more the American figure is +(decimal − 1) × 100, rounded. Below 2.00 it is −100 ÷ (decimal − 1), rounded. The fraction is the one with the smallest denominator (up to 100) that matches decimal − 1 to within 0.0005, so 2.50 shows as 3/2 and 3.75 as 11/4.
Why does 1/3 show a decimal of 1.33 but an American price of −300?
The decimal figure is displayed to two places, but the other conversions use the unrounded value 1.3333…. Converting from the unrounded number is what gives exactly −300. Profit and return are also calculated from the unrounded decimal.
What inputs does it reject?
Decimal odds of 1.00 or below, a fraction with a zero or negative part, American odds between −100 and +100, and anything that is not a number return a message asking you to check the format. A comma in decimal odds such as 2,50 is read as a decimal point. Negative stakes are treated as zero.
Is the stake included in the total return?
Yes. Total return is stake × decimal odds, and potential profit is stake × (decimal − 1). A $10 stake at 2.50 shows $15.00 profit and $25.00 return. The figures describe a winning outcome only; a losing outcome returns nothing.
Does it show a bookmaker’s margin or tell me what to back?
No. It converts one price at a time, so it cannot show how much margin is built into a market, and it makes no judgement about any selection. Gambling involves a risk of loss, and whether it is legal depends on where you are.
Betting odds converter: decimal, fractional and American
One price, three notations
Sportsbooks quote the same price in different notation depending on region: decimal in much of continental Europe and Australia, fractional in the UK and Ireland, American moneyline in the United States. The converter takes a price in any of the three, converts it through decimal odds, and prints all three along with the implied probability, the profit and the total return for a stake. The arithmetic is deterministic, so the same price always gives the same numbers.
| Output | Formula | Rounding |
|---|---|---|
| Fractional | (d − 1) as the simplest fraction, denominator up to 100 | Within 0.0005 |
| American, d ≥ 2 | +(d − 1) × 100 | Nearest whole number |
| American, d < 2 | −100 ÷ (d − 1) | Nearest whole number |
| Implied probability | 1 ÷ d × 100 | One decimal |
| Profit / return | Stake × (d − 1) / stake × d | Two decimals |
Worked examples across formats
Decimal 2.50 with a $10 stake converts to 3/2 and +150, an implied probability of 40.0%, profit of $15.00 and return of $25.00. Entering 3/2 as a fraction, or +150 as American, lands on the same decimal 2.50. A favourite works the other way: American −200 is decimal 1.50, which is 1/2, with an implied probability of 66.7%. A $50 stake returns $75.00, of which $25.00 is profit.
| Entered | Stake | Decimal | Fractional | American | Implied | Profit | Return |
|---|---|---|---|---|---|---|---|
| 2.50 (decimal) | $10 | 2.50 | 3/2 | +150 | 40.0% | $15.00 | $25.00 |
| −200 (American) | $50 | 1.50 | 1/2 | −200 | 66.7% | $25.00 | $75.00 |
| 1/3 (fractional) | $30 | 1.33 | 1/3 | −300 | 75.0% | $10.00 | $40.00 |
| 11/4 (fractional) | $10 | 3.75 | 11/4 | +275 | 26.7% | $27.50 | $37.50 |
Reading a conversion
A longer price means a lower implied probability. The 11/4 line implies 26.7%, the 3/2 line 40.0%, the 1/3 line 75.0%. The 1/3 row also shows why the displayed decimal and the American figure can look inconsistent: 1.33 is a rounded display of 1.3333, and −300 is converted from the unrounded number. When you enter a fraction the tool searches for the neatest matching fraction, so values such as 5/2 or 7/4 come back as entered.
Input rules
Pick the format in the selector before typing the price, because the same text means different things in each. “150” in American mode is +150. Decimal odds must be above 1.00, and American odds must be at least 100 in size, since American prices cannot lie between −100 and +100. A price that fails these checks returns a message instead of silently defaulting to a value.
Scope and a note on risk
The converter is an arithmetic aid. It does not compare bookmakers, remove margin from a market, or say which outcome is likely. Betting involves a risk of losing the stake, and legality differs between countries and regions, so check the rules where you live before taking part.
Learn more from an authoritative source:
WikipediaParlay Payout Calculator
Calculate potential parlay payout from multiple betting selections (legs) using decimal odds.
Implied Probability Calculator
Convert betting odds to implied probability and identify value bets by comparing with your own probability estimate.
Batting Average Calculator
Calculate cricket or baseball batting average and related performance statistics.
Moneyline Payout Calculator
Calculate moneyline bet profit and return for American odds favourites and underdogs.
Golf Handicap Calculator
Calculate your golf handicap index from recent scores using the World Handicap System formula.
Cricket Run Rate Calculator
Calculate current run rate, required run rate, and match projections for cricket innings.
Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →