Expected value in one line
Expected value is what a bet returns on average per unit staked: EV = (chance of winning × odds) − 1. If a coin flip is offered at odds of 2.10 when the fair price is 2.00, the chance of winning is 50%, so EV = 0.5 × 2.10 − 1 = +5%. Stake 100 kr and you expect to make 5 kr on average.
'On average' matters. The bet still loses half the time. +EV is a statement about the price, not about the next result.
Where do the fair odds come from?
Nobody knows the true chance of a football match. What you can do is borrow the best estimate available: the odds at Pinnacle, a bookmaker known for low margins that welcomes sharp bettors and moves its prices quickly when smart money arrives.
Every bookmaker builds a margin (the 'vig') into its odds, so the implied chances add up to more than 100%. Removing that margin — with a method such as Shin's — leaves an estimate of the fair chance for each outcome. Compare that with the odds at another bookmaker and you can see where the price is too generous.
Why one bet proves nothing
A 5% edge is small next to the swings of luck. Over 100 bets at odds around 2.00 a fair-priced bettor's profit routinely lands 10 units above or below expectation. You only see the edge over hundreds of bets, which is why the closing line (see our guide to closing line value) is a better early signal than profit.
The luck meter on My Bets does this calculation for you: it shows the range your results should fall in and whether you're inside it.
Staking: how much per bet?
The Kelly criterion sizes a stake to the edge: f = (odds × chance − 1) ÷ (odds − 1). Full Kelly is aggressive, so most people use half Kelly or less. Sharp Bets suggests stakes in units — one unit is a fixed slice of your bankroll, typically 1% — so the advice works whatever your bankroll is.
The practical catch
Prices move. An edge seen at 08:00 may be gone by 12:00, so check the odds you can actually get before you bet. And bookmakers limit winning customers, so a real edge tends to have a shelf life on any single account.
Betting is never risk-free, and a positive edge doesn't stop long losing runs. Only stake what you can afford to lose.