Odds converter: decimal, fractional and implied probability
Type the odds you were given and see the chance they stand for. Then enter the three prices of one match and see how much of the market is the bookmaker's margin. Nothing you type leaves your browser.
Odds to implied probability
Type a price as the bookmaker shows it. The converter gives the implied probability, the same price in the other format and what a KES 100 stake returns if the bet wins.
Worked example
1 / 2.50 = 0.40, so 40%
Divide 1 by the decimal odds. Odds of 2.50 stand for a 40% chance, so the bet only breaks even if that result comes in four times in ten. The fraction 6/4 is the same price: 6 divided by 4 is 1.50, plus the stake makes 2.50. Illustrative example.
Margin on a 1X2 market
Enter the home, draw and away prices for one match. The converter adds up the three implied probabilities; whatever sits above 100% is the bookmaker's margin, also called the overround.
Worked example
47.62% + 29.41% + 27.78% = 104.81%
Those are the implied probabilities of prices 2.10, 3.40 and 3.60. The 4.81% above 100% is the overround: the bookmaker's margin, built into all three prices at once. Illustrative example.
Conversion tables
The same arithmetic, already done for common prices, so it works on any phone with or without JavaScript. Percentages are rounded to one decimal place; returns include the stake.
| Odds | Implied | KES 100 returns |
|---|---|---|
| 1.10 | 90.9% | 110 |
| 1.25 | 80.0% | 125 |
| 1.50 | 66.7% | 150 |
| 1.75 | 57.1% | 175 |
| 1.90 | 52.6% | 190 |
| 2.00 | 50.0% | 200 |
| 2.20 | 45.5% | 220 |
| 2.50 | 40.0% | 250 |
| 3.00 | 33.3% | 300 |
| 3.75 | 26.7% | 375 |
| 5.00 | 20.0% | 500 |
| 10.00 | 10.0% | 1,000 |
| Odds | Decimal | Implied |
|---|---|---|
| 1/5 | 1.20 | 83.3% |
| 2/5 | 1.40 | 71.4% |
| 1/2 | 1.50 | 66.7% |
| 4/6 | 1.67 | 60.0% |
| 4/5 | 1.80 | 55.6% |
| evens (1/1) | 2.00 | 50.0% |
| 6/4 | 2.50 | 40.0% |
| 2/1 | 3.00 | 33.3% |
| 5/2 | 3.50 | 28.6% |
| 3/1 | 4.00 | 25.0% |
| 4/1 | 5.00 | 20.0% |
| 9/1 | 10.00 | 10.0% |
To turn a fraction into decimal odds, divide the top number by the bottom number and add 1. So 6/4 is 1.50 plus 1, which makes 2.50, and 1 / 2.50 gives the same 40% as the worked example above.
From a chance back to odds
Going the other way, divide 1 by the chance. If you believe a result happens one time in four, 1 / 0.25 = 4.00 is the price at which that belief breaks even. A bookmaker offering less than that is pricing the result as more likely than you do, or keeping a margin on it, or both.
| Chance | Decimal | Fractional |
|---|---|---|
| 90% | 1.11 | 1/9 |
| 80% | 1.25 | 1/4 |
| 75% | 1.33 | 1/3 |
| 66.7% | 1.50 | 1/2 |
| 60% | 1.67 | 4/6 |
| 50% | 2.00 | evens |
| 40% | 2.50 | 6/4 |
| 33.3% | 3.00 | 2/1 |
| 25% | 4.00 | 3/1 |
| 20% | 5.00 | 4/1 |
| 10% | 10.00 | 9/1 |
A two-way market, worked by hand
Some markets have only two outcomes, such as over or under 2.5 goals. Exactly one of them happens, so with no margin the two implied probabilities would add up to exactly 100%.
| Goals | Odds | Implied | Fair share |
|---|---|---|---|
| Over 2.5 | 1.90 | 52.63% | 50.00% |
| Under 2.5 | 1.90 | 52.63% | 50.00% |
| Total | 105.26% | 100.00% |
Illustrative example. Two prices of 1.90 add up to 105.26%, an overround of 5.26%, against 4.81% on the 1X2 example above. Dividing each implied probability by the total takes the margin out: here each side's fair share is 50%, which is fair odds of 2.00. In the 1X2 example the home win's 47.62% divided by 1.0481 gives a fair share of 45.43%. A tipster who calls that home win at 2.10 is claiming its real chance is above 47.62%; the prices themselves put it nearer 45.43%.
What the converter leaves out
- Tax. The return is price times stake, before tax. Excise duty of 5% applies to the amount deposited for betting (Excise Duty Act, First Schedule, Part II, paragraph 4A, as reworded by section 36 of the Finance Act, 2026), and withholding tax of 5% applies to withdrawals made by punters (Income Tax Act, Third Schedule, Head B, paragraph 5(i)). Neither is in the figures above.
- The terms of the bet. A licensee has to display the odds, rules and terms of each bet clearly and may not change a bet's terms after accepting it (L.N. 112 r.23). The price on your bet slip is the one that counts, not the one a tip quoted earlier.
- Several selections at once. In an accumulator the decimal odds multiply and so do the implied probabilities: four legs at 1.50 give odds of 5.06 and a combined chance of 19.75%, before the margin on each leg is counted.
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Questions people ask
What is implied probability?
It is the chance a price stands for, found by dividing 1 by the decimal odds. Odds of 1.50 imply 66.7%, 2.00 implies 50% and 3.75 implies 26.7%. Because the bookmaker's margin is inside the price, the implied figure runs a little higher than the bookmaker's own estimate.
Why does a 1X2 market add up to more than 100%?
The extra is the bookmaker's margin. Illustrative example: a two-way market priced 1.90 and 1.90 adds up to 105.26%, an overround of 5.26%, and the 2.10, 3.40 and 3.60 market above has an overround of 4.81%.
How do I convert fractional odds such as 5/2?
Divide the top number by the bottom one and add 1: 5 divided by 2 is 2.50, plus 1 makes 3.50 in decimal odds. Then 1 / 3.50 gives an implied probability of 28.6%.
Does a low margin make a tip a good one?
No. The margin tells you how much the bookmaker keeps across the whole market. Whether a tip is worth anything depends on whether the real chance of the result is higher than the price implies, and no converter can know that.
Is anything I type stored?
No. The converter runs inside your browser and sends nothing to the server. What you type is not part of what the site's analytics tag sends, and analytics cookies are set only if you allow them; the privacy page has the details.