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What +EV means

What expected value is, how it’s calculated, and what a +EV bet looks like.

TommyLocks, Nov 3, 3 min read

Expected value, or EV, is the average amount a bet would win or lose if you could place it over and over. It’s a way of measuring whether a bet’s price is fair for its true chance of winning.

What +EV, -EV and zero EV mean

• +EV (positive expected value): the payout is bigger than the true chance of winning deserves. Over many bets like it, you’d expect to come out ahead.
• -EV (negative expected value): the payout is smaller than the true chance deserves. Over time, you’d expect to lose.
• Zero EV: the price is exactly fair, and you’d expect to break even.

Implied probability

Every price carries a break-even number, called its implied probability: how often the bet has to win just to break even.

• -200 needs to win 66.7% of the time
• -110 needs 52.4%
• +100 needs 50%
• +150 needs 40%

A bet is +EV when its true chance of winning is higher than its implied probability.

How EV is calculated

EV = (chance of winning × profit if it wins) − (chance of losing × amount staked)

For a $100 bet at -110 that truly wins 55% of the time:

• Win: 55% × $90.91 = $50.00
• Lose: 45% × $100 = $45.00
• EV = $50.00 − $45.00 = +$5.00, a 5% edge

What +EV looks like

The same bet at two different prices. A player’s over truly hits 53% of the time.

• At -105: (0.53 × $95.24) − (0.47 × $100) = +$3.48 per $100. +EV.
• At -115: (0.53 × $86.96) − (0.47 × $100) = -$0.91 per $100. -EV.

Same player, same line, same chance. Only the price changed.

A bet that loses more often than it wins. An underdog at +150 that truly wins 45% of the time:

• (0.45 × $150) − (0.55 × $100) = +$12.50 per $100. +EV, even though it loses more than half the time.

A favorite that wins often but isn’t worth it. A favorite at -250 that truly wins 68% of the time:

• (0.68 × $40) − (0.32 × $100) = -$4.80 per $100. -EV, even though it wins about two out of three times.

The vig and fair odds

Sportsbooks build a margin into their prices, called the vig or juice. A market priced -110 on both sides implies 52.4% + 52.4% = 104.8%, which is more than 100%. Removing that extra 4.8% gives the fair chance of each side, 50% here. Comparing a book’s price to the fair price is one common way to spot +EV bets.

Where +EV bets come from

• Price differences between books: different sportsbooks often price the same bet differently.
• Lines that are slow to move: after news like an injury, some books adjust later than others.
• A better estimate of the true chance: information or analysis the price doesn’t fully reflect.

What +EV doesn’t mean

A +EV bet can still lose. A bet that wins 55% of the time loses the other 45%, and several losses in a row are normal. EV describes the average result over many bets, not the outcome of any single one.

Tools for checking EV

• The EV calculator in Educated Wagers takes any price and your estimated win chance and shows the break-even number, the edge, the expected value on your stake, and a Kelly stake. Enter both sides of a market and it removes the vig to give the fair chance for you.
• The +EV 🔎 tab removes the vig at every book, averages what’s left into a fair price, and lists any book whose price beats it.
• The odds screen shows every book’s price for the same bet side by side, with the best one highlighted.
• The free parlay calculator shows the payout and break-even rate for any parlay, and its EV when you enter your own win chance for each leg.