Compute expected value in currency and percent from odds and your probability estimate, with win/lose breakdown and Kelly sizing.
Expected value is the average result of a bet repeated forever: probability of winning times profit, minus probability of losing times stake. Positive EV means the bet makes money over time; negative EV means it costs money, however good it feels.
The calculator reports EV in both currency and percentage of stake, the edge against the implied price, and the Kelly stake that edge justifies.
EV is only as good as your probability input. Against a sharp market, your estimate is usually the weakest link, and a small error flips a thin positive EV to negative.
For casino games there is nothing to estimate: EV equals stake times (RTP − 1), so a $100 turnover on a 96% game has an expected cost of $4 regardless of how the session feels.
Expected value is arithmetic once you have a probability. Everything difficult about it sits in that probability, and a calculator cannot supply it — feed in the bookmaker’s own implied chance and the answer will always be negative by exactly the margin.
The disciplined workflow is to de-vig the market price first, form your own estimate independently, and only then compare. If the two agree, there is no edge to size, and that is a useful result rather than a failure.
For entertainment, that is your call. As a financial decision, no — and no staking pattern converts negative EV into positive.
Multiply turnover by one minus RTP. Our RTP checker gives the RTP build each casino actually serves, which is the input most people get wrong.