Decimal and fractional odds explained, with examples
Decimal odds give the total return per shilling staked, stake included: 3.50 returns KES 350 on KES 100. Fractional odds give the profit against the stake: 5/2 means KES 5 of profit per KES 2 staked. Both describe the same price, and decimal = fraction + 1.
Two ways to write one price
A price tells you what a winning bet pays. Decimal odds state the total returned per shilling staked, and fractional odds state only the profit. Because the two formats differ by exactly the returned stake, any price can be written either way.
Once you can move between them, you can also turn either into a probability, as shown in the guide on converting betting odds to implied probability. The odds converter performs the same sums if you want to check your own.
How decimal odds work
Decimal odds, written here as D, multiply your stake to give the total return. The stake is inside that return, so profit is the return minus the stake.
Illustrative example
A stake of KES 200 at decimal odds of 2.40. Total return if it wins: 200 × 2.40 = KES 480. Profit: 480 − 200 = KES 280. If it loses, the return is nothing and the KES 200 is gone.
How fractional odds work
Fractional odds are written a/b, read "a to b". For every b shillings staked, a winning bet pays a shillings of profit, and the stake is handed back on top.
Illustrative example
A stake of KES 200 at 5/2. Profit: 200 × 5 ÷ 2 = KES 500. Total return: 500 + 200 = KES 700. The decimal equivalent is 5 ÷ 2 + 1 = 3.50, and 200 × 3.50 = KES 700 as well.
Fractions are often not reduced the way you would in school, so 10/20 and 1/2 are the same price. Compute the division first and the comparison becomes plain.
Converting between the two
From fractional to decimal, divide and add 1. From decimal to fractional, subtract 1 and write the result as a fraction.
Take decimal 2.60. Subtract 1 to get 1.60, which is 160/100, or 8/5 in lowest terms. Check it: 8 ÷ 5 + 1 = 2.60. Take decimal 1.80: 0.80 is 80/100, or 4/5, and 4 ÷ 5 + 1 = 1.80.
Common prices side by side
Each row is the same price written both ways, with the implied probability (1 ÷ D) and the profit and total return on a stake of KES 100. Percentages are rounded to two decimal places.
| Fractional | Decimal | Implied probability | Profit on KES 100 | Total return on KES 100 |
|---|---|---|---|---|
| 1/10 | 1.10 | 90.91% | KES 10 | KES 110 |
| 1/4 | 1.25 | 80.00% | KES 25 | KES 125 |
| 4/5 | 1.80 | 55.56% | KES 80 | KES 180 |
| 1/1 | 2.00 | 50.00% | KES 100 | KES 200 |
| 11/10 | 2.10 | 47.62% | KES 110 | KES 210 |
| 9/4 | 3.25 | 30.77% | KES 225 | KES 325 |
| 5/2 | 3.50 | 28.57% | KES 250 | KES 350 |
| 6/1 | 7.00 | 14.29% | KES 600 | KES 700 |
Odds-on, evens and odds-against
Fractional odds have everyday names. "Evens" is 1/1, where profit equals stake and the decimal price is 2.00. "Odds-against" means the fraction is above 1/1, so the profit is larger than the stake, as in 9/4. "Odds-on" means the fraction is below 1/1, so the profit is smaller than the stake, as in 1/4.
The lower the price, the higher the implied probability, but the figure still includes the bookmaker's built-in charge. That charge is explained in the note on what overround means, and the sums are set out in how to calculate the bookmaker's margin.
Mistakes that come from mixing the formats
- Treating 5/2 as 5.2 or 2.5. The fraction is a division, 5 ÷ 2 = 2.50, and the decimal price is that plus 1, which is 3.50.
- Forgetting the stake. A fractional price states profit only. KES 100 at 5/2 earns KES 250 profit but receives KES 350 in total.
- Thinking a larger number means a better price. A fractional 1/10 and a decimal 1.10 are the same price. Compare formats only after converting.
- Reading profit as return. Decimal 1.25 on KES 100 returns KES 125, which is a profit of only KES 25.
- Judging by the stake you can afford. Long prices such as 6/1 lose far more often than they win, so set limits first, as covered in the guide on setting a betting budget and limits.
What the law says about showing odds
Regulation 23(1) of the Gambling Control (Conduct of Gambling Operations) Regulations, 2026 says a licensee shall clearly display betting odds, rules and terms applicable to each bet. The regulation does not choose between decimal and fractional formats, so a reader should expect to meet either. Section 71(1) of the Gambling Control Act, 2025 sets the minimum online bet at twenty shillings, which is the smallest stake the examples above scale down to; see the note on the minimum online stake.
Betting is for adults aged 18 and over. Gambling is addictive: a price is the cost of a bet written as a number, and no format changes the long-run result.
Questions and answers
Are 5/2 and 3.50 the same price?
Yes. 5/2 is 5 divided by 2 = 2.50 of profit per shilling, and adding the returned stake gives 3.50. A KES 100 stake returns KES 350 in total either way, which is KES 250 of profit.
Which format is better?
Neither pays more. They are two ways of writing one price, so the choice is about which is easier for you to read. Decimal makes comparison and arithmetic simpler because the stake is already included.
What do odds-on and odds-against mean in fractional odds?
Odds-against means the fraction is larger than 1/1, so the profit exceeds the stake, for example 5/2. Odds-on means the fraction is smaller than 1/1, for example 1/4, so the profit is smaller than the stake. In decimal terms these are prices above 2.00 and below 2.00.
Can decimal odds be below 1.00?
No. A winning bet returns the stake plus any profit, so decimal odds are at least 1.00. A price of exactly 1.00 would return only the stake and pay no profit.
Does Kenyan law require a particular odds format?
Regulation 23(1) of the Gambling Control (Conduct of Gambling Operations) Regulations, 2026 requires a licensee to clearly display betting odds, rules and terms applicable to each bet. It does not name a format.