Expected value is the long-run average result of a bet: your win probability times the payout, minus the losing side. It answers one question — if your probability is right, does this price pay enough? — and nothing more. It does not predict this bet, and it cannot rescue a bad probability estimate.
Your estimate — from your model, your handicapping, wherever. EV is only as honest as this number.
$100 at this price wins $90.91
EV per $100 staked
+$5.00
Long-run average result of this bet, per $100
Break-even probability
52.38%
The win rate this price implies (vig included)
Your clearance
+2.62%
Your probability minus the break-even bar
Positive EV means if your probability is right, the price pays more than it should — averaged over many bets, not this one. It is not a prediction that this bet wins. Comparing against a de-vigged fair price instead? Use the no-vig calculator.
With decimal odds d, win probability p, and a $100 stake:
The break-even probability is the price's own implied probability — at −110 you need 52.38% just to tread water, because the extra 2.38 points over a coin flip is the book's margin. EV is positive exactly when your probability clears that bar.
The honest caveat, stated plainly: the entire output hinges on the probability you type in. A +EV readout from an optimistic estimate is worthless. If your number comes from a model, the test that matters is whether the model's prices beat the closing line over time — that is how we grade our own models. Once a bet clears the bar, sizing it is the Kelly calculator's job.
More free tools
These calculators run the exact helpers the Blitzen terminal uses on every board. See them applied to real markets — and how we grade everything against the close.