What EV means
Expected value estimates the average profit or loss if comparable decisions were repeated many times.
The formula
EV = estimated probability × decimal odds − 1. At 52% and odds 2.10, EV is +9.2%.
Money expectation
Multiply EV by stake. A 20-unit stake at +9.2% EV has expected profit of 1.84 units, not a guaranteed outcome.
The hard part
The formula is easy; estimating probability accurately is difficult. Small errors can reverse the result.
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Odds & Value CalculatorFrequently asked questions
Can positive EV lose? — Yes, often in the short term.
Is +5% EV always good? — Only if the probability estimate is reliable.