How to use this calculator
- Enter the bookmaker's decimal betting odds.
- Enter your estimated probability and optional stake.
- Review implied probability, fair odds, expected value and stake guidance.
Worked example: Odds of 2.10 imply 47.62%. At a personal estimate of 52%, fair odds are 1.92 and the calculated EV is positive.
Frequently asked questions
How do decimal odds convert to probability?
Divide 1 by the decimal odds and multiply by 100. For example, odds of 2.00 imply a 50% probability before bookmaker margin.
What makes a bet positive expected value?
A bet has positive expected value when your estimated probability is higher than the probability implied by the offered odds.
Does this calculator guarantee profit?
No. It only calculates the entered assumptions.
Can I use it for real bets?
Use it as an analytical aid and verify every input and market rule.