Expected value (EV) calculator

What a bet is worth on average, from your book's odds and the fair chance it wins.

Result

Fair chance: 42.0%
Fair odds: +138
Break-even chance at your odds: 40.0%
Expected value: $5.04
EV per $1: 5.0%

Worth it: positive expected value

Pro fills in the fair price from the sharp market for every bet at your books, and finds the best places to use a boost tonight. See Pro

Get this math on every promo at your books

Parity Odds Pro prices every bet, prop, and promo against the fair price, every few minutes. A research tool, not a sportsbook.

How it works

Expected value is what a bet wins or loses per bet on average if you placed it many times. Positive EV means the price is better than the bet's real chance of winning.

Enter your book's odds and the fair price from a sharp book. We take the vig out of the sharp price to get the fair chance and compare your price against it.

How do you calculate expected value?

Multiply the chance of winning by what you'd win, then subtract the chance of losing times your stake. The calculator above starts with an example: $100 at +150, when a sharp book has the same side at +130 / -150.

With the vig removed, the fair chance is 42.0% (about +138). A 42.0% chance of winning $150 against a 58.0% chance of losing $100 comes to $5.04, or 5.0% of the stake. At +150, the bet only needs to win 40.0% of the time to break even, so it clears the bar.

Where does the fair chance come from?

From the market. Sharp books run low margins and move their prices quickly when informed bettors bet, so their prices with the vig removed are a strong estimate of the real odds. Beating the closing line, the last price before the game, is the best sign your estimates are right; closing-line value explains how to track it.