Expected Value (EV) in Sports Betting

Expected value (EV) is the average amount a bet would win or lose if you could place it an infinite number of times. It is the foundation of every disciplined betting strategy: instead of asking “will this bet win?” you ask “is this bet priced better than its true probability?”

The formula

For a single bet, expected value is:

EV = (p × profit) - ((1 - p) × stake)

where p is your estimated probability of winning, profit is what you collect if it hits, and stake is what you risk. If EV is positive, the bet is in your favor over the long run.

A worked example

Suppose a player’s rushing-yards Over is priced at -110, and you estimate the true chance of the Over at 55%. At -110 you risk $110 to win $100. Then:

• Win: 0.55 × $100 = +$55.00
• Lose: 0.45 × $110 = -$49.50
• EV = $55.00 - $49.50 = +$5.50 per $110 staked

That’s roughly a 5% edge — small per bet, but meaningful over hundreds of wagers. Try your own numbers in the EV calculator.

EV vs. the implied odds

The odds themselves imply a probability. A -110 price implies about 52.4%. If your estimate is higher than the implied number, you have a positive edge. Stripping the bookmaker’s margin first gives a cleaner comparison — see no-vig fair odds.

Why it matters

Winning bettors lose plenty of individual bets. What separates them is consistently betting +EV and letting a large sample do the work — which is also why variance and sample size matter so much. Every projection on PropProphet exists to help you spot where the market price and the likely outcome disagree.

Frequently asked