Enter a moneyline with its sign and the converter returns the fraction, reduced, alongside the decimal price and the implied probability. Both formats already describe profit against stake, so no stake needs removing. A positive line divides by 100, a negative line divides 100 by itself, and the result reduces.
Two Formats That Already Speak the Same Language
A World Cup outright quoted at +225 on a US site and 9/4 in a UK antepost list is one price written twice. Decimal odds include your stake and these two do not, which makes the conversion between them the shortest of the six.
Positive moneylines become numerator over 100: +225 reduces to 9/4.
Negative moneylines become 100 over the absolute value: -300 reduces to 1/3.
| American | Fractional | Decimal |
|---|---|---|
| -300 | 1/3 | 1.33 |
| -200 | 1/2 | 1.50 |
| -140 | 5/7 | 1.71 |
| +105 | 21/20 | 2.05 |
| +140 | 7/5 | 2.40 |
| +225 | 9/4 | 3.25 |
| +500 | 5/1 | 6.00 |
| +1000 | 10/1 | 11.00 |
A Worked Example
One line either side of evens.
- +150: divide by 100 for 150/100, which reduces to 6/4. Some books print the same price as 3/2.
- -125: divide 100 by 125 for 100/125, which reduces to 4/5.
Sense-check both. At +150 a 100 stake wins 150, and at 6/4 a 4 stake wins 6 – the same ratio scaled down. At -125 you risk 125 to win 100, and 4/5 risks 5 to win 4. The arithmetic never left the page, only the units did.
Reading the Fraction You Get Back
The sign of the moneyline maps onto the shape of the fraction. Negative lines always produce odds-on fractions with the smaller number on top, so -140 becomes 5/7 and risks 7 to win 5. Positive lines produce odds-against fractions: +140 becomes 7/5.
For probability, add the two halves of the fraction and divide the denominator by the sum. With 9/4 that gives 4 ÷ 13 = 30.8%, the break-even win rate the price demands. The Implied Probability Calculator handles the same step from a decimal input.
Fractional format also carries each-way terms, which arrive as a fraction of the win odds rather than as a price of their own. The Each-Way Calculator settles both halves of that bet.
Where the Two Ladders Disagree
Arithmetic gives a clean answer and a bookmaker’s board may not print it. A moneyline of +105 converts exactly to 21/20, which no UK book has ever chalked up; the nearest rung on the traditional ladder is 11/10, which is a decimal price of 2.10 rather than 2.05. The conversion is right and the display is unavailable, and the gap between them is real money over a season.
American odds carry a hole of their own. Nothing exists between -100 and +100, and both of those write the fractional price 1/1. A US book has no way to quote a shade either side of evens, so it moves to -105 or +105 and skips the ground in between.
The stubborn part is that neither ladder affects value. Rewriting -110 as 10/11 leaves the bookmaker’s margin exactly where it sat, and a market showing two sides at -110 prices at 104.8% however you display it. The Hold / Vig Calculator returns that as a 4.6% hold. Decimal is where the day-to-day football betting work happens, since neither the fractional ladder nor whole-number moneylines can express the differences an EV calculation turns on.
Further Reading
- All betting calculators: the full library of 34 free tools
- Glossary: the terms you will see across Gecko Edge
What is +150 in fractional odds?
+150 converts to 6/4, which some bookmakers write as 3/2. Divide 150 by 100 and reduce. Both forms mean the bet pays 1.5 times the stake in profit, so a 20 stake wins 30. The decimal equivalent is 2.50 and the implied probability is 40%.
What is -125 in fractional odds?
-125 converts to 4/5. Divide 100 by 125 to get 100/125, then reduce. The price risks 5 to win 4, or 125 to win 100 in moneyline terms. In decimal that is 1.80, with an implied probability of 55.6%.
How do I convert negative American odds to a fraction?
Put 100 over the absolute value of the line and reduce the result. A line of -200 becomes 100/200, which reduces to 1/2. A line of -140 becomes 100/140, or 5/7. Every negative moneyline produces an odds-on fraction, since the stake is larger than the profit it wins.
Why do the converted fractions not match the bookmaker’s board?
Bookmakers price from a traditional ladder of fractions rather than from exact arithmetic, and that ladder has gaps. A conversion may produce 21/20 or 100/140 where the board offers 11/10 or 5/7. The converted number is mathematically correct; the printed one is the price you can back, and it usually rounds against you.