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Expected Value

Does that price have value?

Expected Value tells you whether a bet is mathematically good in the long run, regardless of whether this single one wins or loses. If you reckon something happens 55% of the time and the bookmaker pays 2.10 (= 47.6% implied), there's value. If they pay 1.70 (= 58.8% implied), there isn't.

The formula

EV = prob × win − (1−prob) × stake

You stake EUR1 at odds 2.10, true prob 55%:
= 0.55 × (2.10 − 1) − 0.45 × 1
= 0.605 − 0.45 = +EUR0.155 EV
  • · Across 100 similar bets, you win +EUR15.5 in expected value (not a guarantee — expected).
  • · The implied prob of an odds is 1/odds. 2.10 = 47.6%. Anything above that gives you value.
  • · The bookmaker bakes in a margin (juice): your true prob needs to be higher than the implied just to break even long term.

Important: EV is only as good as your estimate. If you think something is 60% but reality is 40%, the EV you calculated is a lie. That's why betting with a brain means measuring your hit rate and CLV in public — to find out whether your estimates can be trusted.

The decimal odds the book is offering (e.g. 2.10).

%

How likely YOU think it is to happen (0-100).

Expected Value

+15.50%

Bet with value. Long term, for every EUR1 staked you'd win +15.50c.

Implied probability of the odds

47.62%

What your probability needs to clear just to break even.

Your edge

+7.38 pp

How far above break-even your estimate sits.