Fractional odds explained with real prices
Fractional odds like 17/4 show profit per unit staked. How to read them and convert them to decimal and to a chance, using this week's real Desk prices.
On this page
Fractional odds tell you the profit for each unit you stake. At 4/1 you win 4 for every 1 staked and get the stake back, so 10 returns 50. To turn a fraction into decimal odds, divide the top by the bottom and add 1: 4/1 is 5.0. To turn it into a chance, divide the bottom by the top plus the bottom: 4/1 is 1 in 5, or 20%. That is all there is to the format. It changes how the price looks, never what it pays.
Reading a fraction
The number on the left is profit, the number on the right is stake.
| Fraction | Read it as | Profit on 10 | Total return on 10 |
|---|---|---|---|
| 4/1 | win 4 for every 1 | 40 | 50 |
| 17/4 | win 17 for every 4 | 42.50 | 52.50 |
| 7/5 | win 7 for every 5 | 14 | 24 |
| 4/6 | win 4 for every 6 | 6.67 | 16.67 |
When the left number is smaller, as in 4/6, the price is odds-on: you win less than you stake. That idea has its own explainer in odds-on and odds-against explained.
This week's Desk prices as fractions
Every BAI8 card shows decimal prices. Here are this morning's best prices converted. Bookmakers that show fractions round to a familiar one, so the exact fraction and the one you would usually see can differ slightly.
| Card | Best price (decimal) | Exact fraction | Usual fraction | Implied chance | Our chance |
|---|---|---|---|---|---|
| Gent at SC Braga | 5.25, Coolbet | 17/4 | 17/4 | 19.0% | 43.8% |
| Lech Poznań v Sunderland | 5.00, Nordic Bet | 4/1 | 4/1 | 20.0% | 40.6% |
| Feyenoord at Real Betis | 5.60, Unibet (NL) | 23/5 | 9/2 is 5.50 | 17.9% | 37.8% |
| Lugano at Getafe | 4.62, 1xBet | 181/50 | 18/5 is 4.60 | 21.6% | 38.9% |
| Pelicans v Pacers | 2.43, 1xBet | 143/100 | 7/5 is 2.40 | 41.2% | 59.1% |
| Amed SK at Samsunspor | 2.33, betPARX | 133/100 | 4/3 is 2.33 | 42.9% | 58.1% |
Prices quoted between 04:00 and 04:58 UTC on 21 October. The gap between the implied chance and our chance is the edge on each card, and what that gap means is in what a positive edge actually means.
The three conversions
- Fraction to decimal: top ÷ bottom + 1. 17/4 = 4.25 + 1 = 5.25.
- Decimal to fraction: subtract 1 and write what is left as a fraction. 5.60 − 1 = 4.60, which is 23/5.
- Fraction to chance: bottom ÷ (top + bottom). 17/4 = 4 ÷ 21 = 19.0%.
The chance you get is the bookmaker's implied chance, margin included. Why that margin matters is in what the bookmaker's margin really costs you.
Why rounding matters a little
A fraction like 9/2 is easy to read but rounds 5.60 down to 5.50. On a single bet the difference is small; across hundreds it is real money. If your bookmaker offers decimal odds, they are usually the more precise view of the same price, which is the argument in why odds formats do not change the bet.
What this does not tell you
A fraction tells you what a bet pays, not whether it is worth taking. That depends on your own estimate of the chance, and ours are estimates, not promises. The usual fractions above are typical roundings; a given bookmaker may show a different one.
18+. Bet only what you can afford to lose.
Common questions
How do fractional odds work?
The first number is your profit and the second is your stake. At 4/1 you win 4 for every 1 you stake, and get your stake back, so a 10 stake returns 50.
How do you convert fractional odds to decimal?
Divide the first number by the second and add 1. 17/4 is 4.25 plus 1, which is 5.25 in decimal.
How do you turn fractional odds into a probability?
Divide the second number by the sum of both. 4/1 is 1 divided by 5, which is 20%. 17/4 is 4 divided by 21, about 19%.
What does odds-on mean in fractional odds?
The first number is smaller than the second, as in 4/6. You win less than you stake, and the implied chance is above 50%.
Do fractional odds pay differently from decimal odds?
No. The same price written two ways pays the same. Fractional prices are often rounded to a familiar fraction, so the decimal can be slightly more precise.