Odds converter with implied probability
Type a price in any of the three common formats. The tool rewrites it in the other two, shows the implied probability (1 divided by the decimal odds) and the total return on a stake in shillings. It converts numbers; it cannot predict a result.
Implied probability
- Decimal odds
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- Fractional odds
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- American odds
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- Total return if the bet wins
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- Of which profit
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The return if the bet wins: stake plus profitKES 100.00 + KES 150.00 = KES 250.00
The shaded part is your stake: 40.00% of the return, the same figure as the implied probability.
The formulas the converter uses
Everything is first turned into decimal odds, written D. Decimal odds are the total paid back per shilling staked, including the stake itself.
Going back from decimal: the fractional price is D − 1 written as a fraction. The American price is (D − 1) × 100 with a plus sign when D is 2.00 or more, and 100 ÷ (D − 1) with a minus sign when D is below 2.00.
Illustrative example
A price of 3/2 means 3 shillings of profit for every 2 staked. In decimal form that is 3 ÷ 2 + 1 = 2.50, and in American form +150. The implied probability is 1 ÷ 2.50 = 0.40, or 40%. A stake of KES 100 would return KES 250 if the bet won, and KES 0 if it lost.
Reference table
| Decimal | Fractional | American | Implied probability |
|---|---|---|---|
| 1.25 | 1/4 | −400 | 80.00% |
| 1.50 | 1/2 | −200 | 66.67% |
| 1.80 | 4/5 | −125 | 55.56% |
| 2.00 | 1/1 | +100 | 50.00% |
| 2.50 | 3/2 | +150 | 40.00% |
| 3.00 | 2/1 | +200 | 33.33% |
| 4.00 | 3/1 | +300 | 25.00% |
| 5.00 | 4/1 | +400 | 20.00% |
| 10.00 | 9/1 | +900 | 10.00% |
What the result does not tell you
A calculator cannot predict results. The implied probability is a property of the price, not a forecast of the event. It also contains the bookmaker's margin, so it overstates the chance the price was built on.
To see how large that margin is, put all the prices of one market into the margin calculator. The reasoning behind each formula is laid out in the guide on converting betting odds to probability.
The stake field is there to make the price concrete, not to suggest an amount. Note that section 71(1) of the Gambling Control Act, 2025 sets twenty shillings as the least a player may bet online. A way to fix your own ceiling is in the session budget planner.
Questions and answers
Which odds format is the easiest to read?
Decimal odds, because the number is the total return per shilling staked, stake included. A stake of KES 100 at 2.50 returns KES 250 if the bet wins, of which KES 150 is profit.
Is the implied probability the real chance of the outcome?
No. It is the chance that the price corresponds to, and it includes the bookmaker's margin. The implied probabilities of all outcomes in a market add up to more than 100%.
Why does the fractional result sometimes look unusual?
The tool finds the simplest fraction, with a denominator of at most 100, that matches the decimal price. Printed fractional odds use a traditional set of fractions, so a converted figure can differ slightly from what a bookmaker would print.
Does the converter store what I type?
No. The calculation runs in your browser, nothing is sent anywhere and the figures disappear when you reload the page.