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MO STATS · FREE CALCULATOR
Expected Value Calculator
Enter possible net outcomes and their probabilities to calculate their weighted average and spread.
No account to calculateNo real-money wageringTransparent assumptions
CALCULATOR
Expected value
Calculate the average net payoff of a repeated two-outcome decision.
Start with your assumptions
Enter values and calculate to see the result, method, and assumptions.
PUT YOUR JUDGMENT TO WORK
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Worked example
- Expected net outcome
- 10.00
- Variance
- 9,900.00
- Standard deviation
- 99.4987
A 55% chance of gaining 100 and a 45% chance of losing 100 gives 0.55 × 100 + 0.45 × (−100) = 10. The expected outcome is an average across the stated model; an individual trial still gains or loses 100.
Example inputs
- outcomes:
[{"value":100,"probability":0.55},{"value":-100,"probability":0.45}]
Method
Expected value is Σ pᵢxᵢ. Variance is Σ pᵢ(xᵢ − E[X])², and standard deviation is the square root of variance. Enter net outcomes consistently: a gain of 100 is +100 and a loss of 100 is −100.
Assumptions
Probabilities must be between zero and one and sum to one. The calculator checks the supplied distribution; it does not establish whether your probabilities describe reality. Rare losses excluded from the inputs are excluded from the result.
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