Convert odds
The four fields describe the same price: edit one, the others follow.
Result
- Gross return
- €25.00
- Net profit
- €15.00
Warning:
The implied probability shown still contains the bookmaker margin. It does not describe the real probability of the outcome.
Enter odds in any of the four formats — 2.50, 3/2, +150 or 40% — and the other three update instantly. The tool also shows the gross return and the net profit for the stake you enter. The implied probability you get still contains the bookmaker margin.
How does this converter work?
The four fields describe the same price. Edit one and the other three are recalculated immediately: the converter reduces every entry to decimal odds, its pivot unit, then derives the other notations from it.
Lenient input is deliberate: 2.50 and 2,50 are equivalent, so are 40% and 40, and the + sign of positive American odds is optional. An unrecognised entry triggers an explicit message rather than a silently wrong result.
The formulas used
Every format is converted into decimal odds first.
fractional → decimal: numerator ÷ denominator + 1, so 3/2 → 2.50
positive American → decimal: odds ÷ 100 + 1, so +150 → 2.50
negative American → decimal: 100 ÷ |odds| + 1, so −200 → 1.50
implied probability: 1 ÷ decimal odds, so 2.50 → 40%
The gross return is odds × stake, stake included; the net profit is gross return − stake. For 10 € staked at 2.50: 25 € gross return, 15 € net profit.
A few examples
The most common equivalences, exactly as the tool produces them.
Odds of 1.50 are written 1/2 in fractional and −200 in American, for an implied probability of 66.67%. Odds of 2.00 are written 1/1 and +100, that is 50%. Odds of 2.50 are written 3/2 and +150, that is 40%. Odds of 5.00 are written 4/1 and +400, that is 20%.
The boundary between positive and negative American odds sits exactly at decimal odds of 2.00, in other words at 50% implied probability.
What each format counts
The difference between the three formats is not mathematical, it is accounting: they do not count the same thing.
The decimal format counts the total return, stake included. The fractional format counts the net profit alone, hence the + 1 in its conversion. The American format takes a reference stake of 100 and switches notation depending on whether the outcome is the favourite or not.
That difference explains the most common confusion: decimal odds of 3.00 and fractional odds of 2/1 describe the same bet, even though the figures displayed differ. Each format in detail, with its typical misreadings, is covered on odds formats.
Why the fraction shown is sometimes approximate
Not every decimal price lands on a simple fraction. Odds of 2.37 would be written exactly as 137/100, which is of no practical use. The converter therefore keeps the closest readable fraction, capping the denominator.
The difference introduced is tiny and has no consequence for reading, but it is real: odds converted back from the fraction shown can differ from the odds entered by a few thousandths. That is a limit of the fractional format, not an imprecision in the calculation.
What implied probability does not say
The implied probability shown is derived from the odds you entered: it still contains the bookmaker margin.
Add up the implied probabilities of every outcome in a market and the total will exceed 100%. Each probability taken in isolation is therefore slightly overstated compared with what the market actually estimates. Removing that excess requires working on the complete market — which is what the bookmaker margin calculator does.
And even once the margin is removed, the result remains an estimate derived from commercial prices. That limit is covered in detail on implied probability.
The takeaway. Converting odds changes nothing about what they are worth. A format does not make a price better: it writes it differently.
Frequently asked questions
Which odds formats does this converter accept?
Decimal (2.50 or 2,50), fractional (3/2), American (+150 or -200) and implied probability expressed as a percentage (40%).
Does the converter require an account?
No. The calculation runs in the browser, with no account, no data sent and no record of the odds you enter.
Why are the fractional odds shown approximate?
Because not every decimal price maps onto a simple fraction. The converter keeps the closest readable fraction, which can introduce a tiny difference.
Is the implied probability shown the real probability?
No. It is derived from the odds you enter, which contain the bookmaker margin. It does not describe the real probability of the outcome.
What do negative American odds mean?
They show the stake needed to win 100 in net profit. Odds of -200 correspond to decimal odds of 1.50, that is an implied probability of 66.67%.
Sources & method
This converter applies the standard conversion formulas between the three common odds formats and implied probability, described in detail on the "odds formats" page.
- Every entry is first converted into decimal odds, the pivot unit of the four fields.
- Fractional → decimal: numerator ÷ denominator + 1. Positive American → decimal: odds ÷ 100 + 1. Negative American → decimal: 100 ÷ |odds| + 1.
- Implied probability = 1 ÷ decimal odds; gross return = odds × stake; net profit = gross return − stake.
- The fractional odds shown are the closest readable approximation (denominator capped at 100).