How this tool works
This implied probability calculator turns a price into a percentage and, if you add the other side, shows the book overround.
Odds to probability
Fill one, two or three outcomes. Blank rows are ignored.
Accepts fractional (5/2), decimal (3.50) and American (+250 / -110) odds.
Reading the number
Implied probability = 1 / decimal odds. A fair two-way market totals 100%. Anything above that is the bookmaker margin. If you believe the real chance is higher than the implied figure, the price has value.
FAQ
What is a good overround?
Tighter markets sit near 102–105%. A 110%+ two-way market is expensive.
Can I use this on a 1X2 football market?
Yes. Enter home, draw and away prices. The three percentages should sum above 100%.
Is this the same as true probability?
No. It is the chance baked into the price, including margin.
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Important note
These calculators are for information only. Bookmaker rules, Rule 4, dead heats, each-way terms, maximum payouts and promotion conditions can change the real return. 18+ only. Please gamble responsibly.