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 chance into one figure: the expected value, or EV.
A positive EV means the price is bigger than your estimate says it should be. It doesn’t mean the bet will land.
Expected value calculator
Key points
- EV per £1 = your chance × decimal odds − 1.
- Implied chance = 1 ÷ decimal odds.
- Your fair odds = 1 ÷ your chance.
Using the calculator
Enter your stake, the decimal odds and the chance you give the bet as a percentage. The calculator then shows four things: the EV in pounds, the EV per £1 staked, the chance the odds imply and the fair odds for your chance.
If you aren’t sure where your chance should come from, start with the bookmaker’s price with the margin removed. The fair odds calculator does that for you.
Worked example
Worked example
You stake £20 on Crystal Palace to beat West Ham at 3.30 (prices for illustration only) and rate their chance at 33%.
EV per £1 = 0.33 × 3.30 − 1 = 0.089, so the EV is about +£1.78 on a £20 stake.
The implied chance is 1 ÷ 3.30 = 30.3%, and your fair odds are 1 ÷ 0.33 = 3.03. The price is above your fair odds, so the EV is positive.
Reading the results
EV is a long-run average. Any single bet here either pays £46 profit or returns nothing; it never pays £1.78. Over many bets with real value, results tend to move towards the EV, but quiet spells still happen, and our expected value betting guide explains why.
The answer also depends entirely on your 33%. If the true chance is 28%, the EV becomes about −£1.52 instead, which is why it pays to be honest about how good your estimates really are.
Using it with other tools
An expected value calculator tells you whether a price looks good, not how much to stake, and for that you need 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 stay fun. Set a budget before you start, only bet what you can comfortably afford, and take a break whenever you need one. For free, confidential support, visit BeGambleAware.org or call the National Gambling Helpline on 0808 8020 133.