Expected value calculator
EV tells you whether a bet wins or loses money long-term. We compute it from your fair price vs the offered price.
True probability
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EV per bet
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EV %
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Enter offered odds, fair odds and stake.
How to use this calculator
- Enter the decimal odds offered.
- Enter your estimated fair odds (no-vig or your model price).
- Enter the stake.
- The EV per bet appears as both a £ amount and a percentage.
Worked example
Offered 2.10, fair 1.95, £10 stake. True probability = 1/1.95 = 51.3%. EV = (0.513 × 1.10 × 10) - (0.487 × 10) = £5.64 - £4.87 = £0.77 per bet, or +7.7%.
Common questions
Why is +EV the only thing that matters?
Because over a long enough run, results converge on expectation. Picking winners means nothing if you keep taking -EV prices.
Where does fair odds come from?
Either a no-vig calculation from a sharp book (Pinnacle, betfair exchange), or your own model.