Fractional odds are the traditional format in the UK and Ireland, especially in horse racing and football. You will see prices like 5/2, 4/6 or "evens". They look old-fashioned, but the logic is simple once you know which number is which.
How to read a fraction
A fractional price is written as profit / stake.
- 5/2 means you win 5 for every 2 you stake.
- 4/6 means you win 4 for every 6 you stake.
- 1/1, called evens, means you win 1 for every 1 you stake.
People often say these out loud: "five to two", "four to six", "evens".
A useful shortcut: if the first number is bigger than the second, the selection is an underdog (you win more than you risk). If the first number is smaller, it is a favorite. A price with a smaller first number is sometimes described as odds-on. A price with a bigger first number is odds-against.
The formula
Profit = stake × (top number ÷ bottom number)
Total return = stake + profit
Worked example: 5/2
You stake 10 at 5/2.
- Profit = 10 × (5 ÷ 2) = 10 × 2.5 = 25
- Total return = 10 + 25 = 35
Worked example: 4/6
You stake 12 at 4/6.
- Profit = 12 × (4 ÷ 6) = 12 × 0.667 = 8
- Total return = 12 + 8 = 20
Worked example: evens
You stake 20 at evens (1/1).
- Profit = 20
- Total return = 40
Converting fractional odds to probability
Implied probability = bottom ÷ (top + bottom)
- 5/2 → 2 ÷ 7 = 28.6%
- 4/6 → 6 ÷ 10 = 60%
- Evens → 1 ÷ 2 = 50%
- 10/1 → 1 ÷ 11 = 9.1%
- 1/4 → 4 ÷ 5 = 80%
This is the key number to keep in mind. A 10/1 shot is not "nearly impossible". It is roughly a one-in-eleven chance, which happens regularly.
Converting to decimal and American
To decimal: (top ÷ bottom) + 1.
- 5/2 → 2.5 + 1 = 3.50
- 4/6 → 0.667 + 1 = 1.67
To American:
- If the fraction is above 1 (odds-against): (top ÷ bottom) × 100, with a plus. 5/2 → +250.
- If the fraction is below 1 (odds-on): −100 ÷ (top ÷ bottom). 4/6 → −100 ÷ 0.667 = -150.
So 4/6, 1.67 and -150 are the same price written three ways.
Common fractions you will see
| Fractional | Decimal | American | Implied % | |---|---|---|---| | 1/5 | 1.20 | -500 | 83.3% | | 1/2 | 1.50 | -200 | 66.7% | | 4/6 | 1.67 | -150 | 60.0% | | 10/11 | 1.91 | -110 | 52.4% | | Evens | 2.00 | +100 | 50.0% | | 6/4 | 2.50 | +150 | 40.0% | | 2/1 | 3.00 | +200 | 33.3% | | 5/1 | 6.00 | +500 | 16.7% |
Notice 10/11. That is the fractional version of -110, the standard price on point spreads and totals.
Why fractions can be awkward
Fractional odds are great for quick mental profit on round stakes, but harder for comparing prices. Is 11/8 better than 7/5? You need to convert to check: 11/8 is 1.375 and 7/5 is 1.40, so 7/5 pays slightly more. Decimal odds make that comparison instant, which is why many people switch formats once they get serious about comparing value.
Fractions are also clumsy for multiplying picks together in a parlay (an "accumulator" in UK terms). Converting to decimal first is the easiest approach. See what is a parlay.
Fractional odds and the house margin
Like every format, fractional prices include a margin. In a two-way market at 10/11 on both sides, each side implies 52.4%, adding up to 104.8%. The extra 4.8% is the bookmaker's edge. Our guide on the vig explains why that matters over many picks.
A quick mental trick
To estimate probability fast, turn the fraction into "X in Y" chances. 3/1 means three losses for every one win in a fair world, so one win in four, or 25%. 7/2 means seven to two, so two wins in nine, or about 22%. With practice you can read these instantly.
Practice reading prices
You can switch between formats in your head more easily if you see lots of real lines. MockSport lets you make free play-money picks on real games with no deposits and no prizes, which makes it a calm place to practice. Check today's lines on the odds page, or read more in the learn hub.
FAQ
What does 2/1 mean?
At 2/1 you win 2 for every 1 you stake. A 10 stake profits 20 and returns 30 total. The implied probability is 1 ÷ 3, about 33.3%.
What does odds-on mean?
Odds-on means the price is shorter than evens, like 1/2 or 4/6. You win less than you stake, and the implied probability is above 50%.
Is 9/4 bigger than 2/1?
Yes. 9/4 equals 2.25 to 1, while 2/1 equals 2 to 1. So 9/4 pays a little more, and implies a slightly lower chance (about 30.8% vs 33.3%).