This expected value calculator shows what a bet is worth on average, based on your own estimate of the chance. It turns the stake, the odds and your win chance into a single figure: the expected value, or EV.
A positive EV means the price is bigger than your estimate says it should be. However, it does not mean the bet will win.
Expected value calculator
The short version
- EV per £1 = your chance × decimal odds − 1.
- Break-even chance = 1 ÷ decimal odds.
- Your fair odds = 1 ÷ your chance.
How to use the expected value calculator
Enter your stake, the decimal odds and the chance you think the bet has, as a %. Then the expected value calculator shows four things: the EV in £, the EV per £1 staked, the break-even chance and the fair odds for your chance.
If you are not sure where your chance comes from, start with the bookmaker’s price minus its margin. The fair odds calculator does that for you.
Worked example
Worked example
You stake £10 at odds of 2.40, and you rate the chance at 45%.
EV per £1 = 0.45 × 2.40 − 1 = 0.08, so the EV is +£0.80 on a £10 stake.
The break-even chance is 1 ÷ 2.40 = 41.7%, and your fair odds are 1 ÷ 0.45 = 2.22. In short, the price is above your fair odds, so the EV is positive.
What the result means
EV is a long-run average. So any single bet either wins £14 or loses £10 here, never £0.80. Over many bets with real value, results tend to move towards the EV, but long losing runs still happen. Our guide to expected value betting explains why.
Also, the answer depends on your 45%. If the true chance is 40%, then the EV is −£0.40 instead. That is why it pays to be honest about how good your estimates are.
Using the expected value calculator with other tools
An expected value calculator tells you whether a price looks good, not how much to stake. For that, see the Kelly calculator. For the maths of averages, the Wikipedia page on expected value is a good reference.
Related guides and calculators
18+ only. Betting should be fun, and every bet can lose. Set a budget you can afford to lose and stick to it. For free, confidential support, visit BeGambleAware.org or call the National Gambling Helpline on 0808 8020 133.