Enter a decimal price and the converter returns the fraction, reduced to its lowest useful terms, with the profit per unit staked shown alongside. The step is a subtraction: decimal odds include your stake, fractional odds do not, so 2.50 becomes 1.50 of profit per 1 risked and prints as 6/4.
Taking the Stake Back Out
An exchange screen quotes 2.375 while the shop board across the road has the same runner at 11/8. The two prices match, and the reason takes one line of arithmetic: subtract the stake from the decimal figure and write what is left as a fraction.
2.375 – 1 = 1.375, which reduces to 11/8. Every conversion runs that way. The denominator is what you risk, the numerator is what the bet pays on top.
| Decimal | Fractional | Profit per 1 staked |
|---|---|---|
| 1.33 | 1/3 | 0.33 |
| 1.57 | 4/7 | 0.57 |
| 2.10 | 11/10 | 1.10 |
| 2.375 | 11/8 | 1.375 |
| 2.75 | 7/4 | 1.75 |
| 3.50 | 5/2 | 2.50 |
| 4.33 | 10/3 | 3.33 |
| 6.00 | 5/1 | 5.00 |
A Worked Example
Two prices, one that converts exactly and one that does not.
- 2.375 decimal: subtract the stake for 1.375, reduce, and the price is 11/8. A 40 stake wins 55.
- 1.83 decimal: subtract the stake for 0.83, which sits fractionally above 5/6 at 0.8333. The board would print 5/6.
- 2.50 decimal: 1.50 of profit, written 6/4 rather than 3/2 in most UK shops, though the two are identical.
The 1.83 line is the one worth holding on to. Its true fraction is 83/100, a price no bookmaker has ever chalked up. 5/6 is what gets displayed, and the difference between them is 0.0033 of a unit.
Reading the Fraction
Compare the two halves. Anything with a numerator larger than its denominator is odds-against, so 11/8 pays more than it risks. Anything with a smaller numerator is odds-on: 4/7 risks 7 to win 4. Equal halves are evens.
For probability, add the two numbers and divide the denominator by the total. With 11/8 that is 8 ÷ 19 = 42.1%. The Implied Probability Calculator does the same job from the decimal side, where it is a single division.
Fractions also govern each-way terms, which are quoted as a fraction of the win odds rather than as a price: 1/5 odds and three places on a 10.0 shot produce place odds of 2.8. The Each-Way Calculator splits the stake and settles both parts.
The Ladder Is a Convention, Not a Calculation
Bookmakers price from a traditional ladder: 1/3, 4/9, 1/2, 8/15, 4/7, 8/13, 4/6, 8/11, 4/5, 5/6, evens, 11/10, 6/5, 5/4 and upward. Decimal prices between two rungs get shown as the nearest one, and the nearest one is rarely in your favour.
That rounding is why a decimal-native bettor comparing an exchange price with a shop board is often comparing 2.36 with 2.375 and calling them the same. Over one bet the gap is trivial. Over a season of shop prices it is a slow leak, and it runs in a single direction.
Conversion also leaves the margin exactly where it was. A price of 5/6 carries whatever overround the bookmaker built into 1.83, and the Hold / Vig Calculator is the tool that measures it. Pricing work happens in decimal for that reason, since a ladder cannot express the small differences an EV test depends on.
Further Reading
- All betting calculators: the full library of 34 free tools
- Glossary: the terms you will see across Gecko Edge
What is 2.50 in fractional odds?
2.50 decimal is 6/4, which some books write as 3/2. Subtract the stake from 2.50 to leave 1.50 of profit per 1 risked, then express that as a fraction. A 20 stake at 6/4 wins 30 for a 50 total return. The implied probability is 40%.
How do you convert a decimal price to a fraction?
Subtract 1 to remove the stake, then write the remainder as a fraction and reduce it. A price of 3.50 leaves 2.50, which becomes 5/2. Where the remainder is a recurring decimal, take the nearest rung on the bookmaker ladder: 4.33 leaves 3.33 and prints as 10/3.
Why does 2.375 show as 11/8 and not 11/8 exactly?
It is exact. 11 ÷ 8 = 1.375, and adding the stake gives 2.375 with no rounding at all. Most decimal prices are less obliging, which is where the ladder takes over and the printed fraction becomes an approximation rather than a conversion.
Are fractional odds still used in football betting?
Less than they once were. UK bookmakers default to fractional on racing boards and in shops, and many football coupons still print them, but online football markets and every exchange run on decimal. Anyone betting across several books ends up converting, since price comparison in mixed formats is slow and error-prone.