The expected value formula
EV equals (probability of winning times profit if you win) minus (probability of losing times amount risked). If your read says a team wins 55 percent of the time and the price pays even money (+100), a $100 bet has EV of (0.55 x $100) - (0.45 x $100) = +$10. Positive means the bet is worth making; negative means it is not.
How to find +EV bets
Start with the no-vig calculator: it removes the book's margin and returns the market-implied probability you compare your price against. The practical method is to strip the book's margin out of the odds to get the fair, no-vig probability, then compare it to your own estimate or to a sharper book's price. When a book's implied probability is lower than that fair, no-vig estimate, the difference is your estimated edge. Line shopping across books surfaces these gaps constantly.
Why EV matters more than winning percentage
You can win most of your bets and still lose money by laying huge prices on favorites, and you can lose most bets and profit by consistently getting the best number on underdogs. Chasing +EV, not a high hit rate, is what compounds a bankroll. Every play on this site is framed around the number, not the outcome of one game.
In the Wise Guy tools
Est. edge (expected value)
How much better this price is than the fair price, per $100, after any fee. A positive edge is a +EV bet: it should profit over many bets, not every time.
Example: +3% means an estimated $3 back per $100 over many bets like it.
How our tools use it: How much better this price is than the market-estimated fair price, per $100 bet, after any exchange fee: (fee-net decimal price x fair chance - 1) x 100. +3% means an estimated $3 return per $100 over many bets if the fair estimate is right. It is an estimate, not a promise.
Check at book
This edge is over 10%. Big edges usually mean one book is slow to move or the fair estimate is noisy, so confirm the price first.
How our tools use it: The edge is over 10%. That usually means one book is slow to move or the fair estimate is noisy. Open the book and confirm the price before you bet.
Edge size
How much better the price was than our estimated fair price when the board first flagged it, after fees. Bigger edges are rarer and noisier.
Example: A 3% edge means an estimated $3 per $100 over many bets, if the fair price is right.
How our tools use it: How far the flagged price was above the board's estimated fair price when it was first seen, after fees. A 3% edge means an estimated $3 per $100 over many bets if the fair price is right. Bigger edges are rarer and noisier.
Frequently asked questions
What does +EV mean?
Positive expected value: the bet is priced better than its fair, no-vig probability estimate, so it is expected to profit over a large sample even though individual bets still lose sometimes.
Can a losing bet still be +EV?
Yes. EV is about the price versus the fair odds estimate, not any single result. A well-priced bet can lose and still have been the right bet to make.
Your next step
- 1Learn itExpected Value (+EV) (this page)
- 2Apply itHow to find value bets →
- 3Run itNo-Vig Calculator →
- 4Master itDay 20: Sharp action, handle and line movement →
Related terms
- Vig (Juice)
- Vig, short for vigorish and also called juice, is the commission a sportsbook builds into its odds.
- Closing Line Value (CLV)
- Closing line value, or CLV, measures whether the price you got on a bet was better than the closing line, the final odds right before the event starts.
- Kelly Criterion
- The Kelly Criterion is a staking formula that sizes each bet in proportion to your edge and the odds, aiming to grow a bankroll as fast as possible without risking ruin.
- No-Vig Fair Odds
- No-vig fair odds are the prices a market would show with the sportsbook's margin taken out.
- Line Shopping
- Line shopping means comparing the price of the same bet across several sportsbooks and exchanges, then placing it wherever it pays the most.
- Implied Probability
- Implied probability is the chance of winning a betting price represents.
- ROI (Return on Investment)
- ROI in sports betting, short for return on investment, is the profit you made divided by the amount you risked, shown as a percentage.
21+. For entertainment and educational purposes, not financial advice. If gambling stops being fun, take a break. 1-800-GAMBLER. Regulated US books only.