Implied Probability Calculator
Turn any odds into a percentage with this implied probability calculator, see how many bets you must win to break even, or type a percentage to get the matching odds.
On this page
- How to use the implied probability calculator
- The formula: from odds to probability
- Break-even win rate: what the 1 in N line means
- From probability to odds: the reverse box
- Why a market’s percentages add up to more than 100%
- Judging a tipster’s record with break-even rates
- Mistakes when reading implied probability
Reverse: probability to odds
The implied probability calculator turns a bookmaker’s price into the chance of winning that price represents. Type odds in any format to get the percentage and a plain line telling you to win about 1 in N bets to break even, or type a percentage to see the decimal odds it matches.
How to use the implied probability calculator
- Enter the odds. Decimal (4.50), fractional (7/2) or American (+350) all give the same answer.
- Read the percentage. This is the implied probability, rounded to two decimal places.
- Read the break-even line. It tells you roughly how often a bet at this price must win for you to finish level.
- Use the reverse box when you start from a percentage. Type your own estimate, such as 60%, to get the decimal odds that match it.
The formula: from odds to probability
With decimal odds the sum is one division: implied probability = 100 ÷ decimal odds. The tool converts other formats first, but you can also work them out directly:
- Fractional a/b: b ÷ (a + b) × 100. For 7/4 that is 4 ÷ 11 = 36.4%.
- Minus American −A: A ÷ (A + 100) × 100. For −150 that is 150 ÷ 250 = 60%.
- Plus American +A: 100 ÷ (A + 100) × 100. For +250 that is 100 ÷ 350 = 28.6%.
Example An away side is priced at 4.50. Implied probability: 100 ÷ 4.50 = 22.2%, so you need to win about 1 in 4.5 bets, which is 2 in every 9. Check it in Naira: nine ₦1,000 bets cost ₦9,000, and two winners at 4.50 return ₦4,500 each, exactly ₦9,000. Win two of nine and you are level; win three and you are ₦4,500 up.
Break-even win rate: what the 1 in N line means
N is simply the decimal odds. At 2.00 you must win 1 in 2; at 1.40 you must win 1 in 1.4, which is easier to picture as 5 in 7. This is the break-even win rate, and it is the fairest way to judge a tipster or your own record: compare how often the bets won with how often they needed to win at the odds taken.
| Decimal odds | Implied probability | Break even by winning |
|---|---|---|
| 1.20 | 83.3% | 5 in 6 |
| 1.50 | 66.7% | 2 in 3 |
| 2.00 | 50.0% | 1 in 2 |
| 3.00 | 33.3% | 1 in 3 |
| 5.00 | 20.0% | 1 in 5 |
| 10.00 | 10.0% | 1 in 10 |
A slip on our 2 odds page at about 2.00 therefore has to land half the time just to stand still, which is why the results history on those pages matters more than any single win.
From probability to odds: the reverse box
Turn the formula around and decimal odds = 100 ÷ probability. If your research says a team wins 60% of the time, the odds that match that view are 100 ÷ 60 = 1.67. Any price above 1.67 pays more than your estimate says it should; a bookmaker’s 1.80 (55.6% implied) would be bigger than your fair price.
That gap is only worth something if your 60% is sound. Build estimates from data, for example with the Poisson goals model, then test the price with the value bet calculator.
Why a market’s percentages add up to more than 100%
Run all three 1X2 prices of a match through the tool and add them up. For 2.05, 3.30 and 3.75 you get 48.8% + 30.3% + 26.7% = 105.8%. The extra 5.8% is the bookmaker’s built-in edge. The margin calculator measures it, and the no-vig tool strips it out to show fair percentages that total exactly 100%.
Judging a tipster’s record with break-even rates
A hit rate on its own says little. Suppose a tipster posts 40 picks at average odds of 1.70 and 24 of them win, a 60% strike rate. The break-even rate at 1.70 is 100 ÷ 1.70 = 58.8%, so the real margin is thin. With ₦1,000 on each pick, ₦40,000 staked brings back 24 × ₦1,700 = ₦40,800: a profit of just ₦800, or 2%. One more loser would have turned it into a ₦900 loss (23 × ₦1,700 = ₦39,100). Always compare the hit rate with the break-even rate of the odds actually taken, including on our own results tables.
Mistakes when reading implied probability
- Reading the percentage as the real chance. It is the bookmaker’s price with margin included, not a forecast.
- Calling short odds safe. Three legs at 1.50 each look comfortable, but together they are 1.50 × 1.50 × 1.50 = 3.375, an implied 29.6%. Our guide to how accumulators work covers why each leg adds risk.
- Ignoring the break-even rate. A run of winners at 1.25 can still lose money if you win fewer than 80% of them.
For the Naira return on any price, use the payout calculator; to rewrite a price in fractional or American form, use the format converter.
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Frequently asked questions
100 ÷ 1.25 = 80%. To break even at that price you must win four bets in every five. Lose more often than one in five and a run of 1.25 picks loses money, even though most of them win.
Divide 100 by the percentage. 40% becomes 2.50, 25% becomes 4.00 and 70% becomes about 1.43. Type the percentage into the reverse box of the calculator and it does the division for you.
No. It is what the price says, and the price includes the bookmaker's margin, so the percentages for all outcomes total more than 100%. It is a useful starting point, but the true chance is usually a little lower than the implied figure.
More than 50%. At exactly 50% you win as much as you lose. Win 55 of 100 bets at 2.00 with ₦1,000 stakes and you get back ₦110,000 on ₦100,000 staked, a ₦10,000 profit.
For a minus price, divide the number by itself plus 100: 150 ÷ 250 = 60%. For a plus price such as +150, divide 100 by the number plus 100: 100 ÷ 250 = 40%.