What does it mean for a bet to have value?

A bet has value when its price pays more than the true chance of winning justifies. If a side wins 42% of the time, any price with a break-even chance below 42% (better than +138) has positive expected value. Value is about the price, not about which team is better.

How do I convert American odds to a probability?

For negative odds, divide the odds by the odds plus 100: -150 is 150 / 250 = 60%. For positive odds, divide 100 by the odds plus 100: +130 is 100 / 230 = 43.5%. That number is the break-even chance: the price pays off only if the side wins more often than that.

What is the vig, and why remove it?

The vig is the sportsbook's margin. Both sides of a market add up to more than 100% (for example 60% + 43.5% = 103.5%); the extra 3.5% is the vig. Scaling both sides down so they add to 100% gives the market's fair chance for each side, which is the baseline for judging any other price.

Is a positive EV bet guaranteed to win?

No. Expected value describes the average over many bets at similar prices, not the result of any one bet. A +3% EV bet on a 42% side still loses 58% of the time, and the fair chance itself is an estimate. Closing line value over a large sample is the best evidence that the edge is real.

How can I tell if my bets had value, after the fact?

Compare the price you got with the closing line, the final price before the game started. Consistently getting better prices than the close (positive closing line value) is the strongest sign your process finds value, because the closing line is the market's most informed price. Wins and losses alone take hundreds of bets to separate skill from luck.

How to tell if a betting line has value

Updated October 1, 2026

A bet has value when its price pays more than the true chance of winning justifies. To check, turn the odds into a break-even chance, remove the sportsbook's margin to find the fair price, and compare that fair price with what every book is offering. Gut feel answers "who wins?". Value answers "is this price worth it?", and only the second question decides results over time.

1.Turn the price into a break-even chance
Every price implies a chance of winning. Below that chance, the bet loses money over time; above it, it makes money.
- Negative odds: odds ÷ (odds + 100). -150 → 150 ÷ 250 = 60.0%
- Positive odds: 100 ÷ (odds + 100). +130 → 100 ÷ 230 = 43.5%
2.Remove the vig to find the fair price
Add both sides: 60.0% + 43.5% = 103.5%. The extra 3.5% is the book's margin (the vig). Divide each side by the total so they add up to 100%:
- Favorite: 60.0 ÷ 103.5 = 58.0% fair chance
- Underdog: 43.5 ÷ 103.5 = 42.0% fair chance, a fair price of +138
This is the market's own estimate with the margin taken out. A sharper market, or several books averaged together, gives a better estimate than one book.
3.Compare that fair price with every book
Books disagree. Suppose another book has the same underdog at +145:
- Break-even at +145: 100 ÷ 245 = 40.8%, below the 42.0% fair chance
- Expected value: 0.420 × 2.45 − 1 = +2.9% per dollar staked
- The same team at the first book's +130: 0.420 × 2.30 − 1 = −3.4%
Same team, same game, opposite answers. The price decides whether a bet has value, not how much you like the team.
4.Size it to the edge, not to your confidence
The Kelly criterion turns an edge into a stake: at +145 with a 42.0% fair chance it comes to 2.0% of a bankroll ($20 per $1,000), and many bettors use half of that ($10 per $1,000) because the fair chance is an estimate. The Kelly calculator does the math.
5.Check the closing line afterwards
Wins and losses are noisy: it takes hundreds of bets to tell skill from luck. The closing line, the last price before the game, is the market's most informed number. If the prices you take are regularly better than the close, that is the clearest sign you are finding value. If they are regularly worse, the wins were probably luck.

Where the Lab does this

EV Game Edges removes the vig across every major US book and shows where a price pays more than fair. Line Analysis tracks how prices moved and where they closed. These are findings about prices, not instructions to bet.

Common questions

What does it mean for a bet to have value?: A bet has value when its price pays more than the true chance of winning justifies. If a side wins 42% of the time, any price with a break-even chance below 42% (better than +138) has positive expected value. Value is about the price, not about which team is better.
How do I convert American odds to a probability?: For negative odds, divide the odds by the odds plus 100: -150 is 150 / 250 = 60%. For positive odds, divide 100 by the odds plus 100: +130 is 100 / 230 = 43.5%. That number is the break-even chance: the price pays off only if the side wins more often than that.
What is the vig, and why remove it?: The vig is the sportsbook's margin. Both sides of a market add up to more than 100% (for example 60% + 43.5% = 103.5%); the extra 3.5% is the vig. Scaling both sides down so they add to 100% gives the market's fair chance for each side, which is the baseline for judging any other price.
Is a positive EV bet guaranteed to win?: No. Expected value describes the average over many bets at similar prices, not the result of any one bet. A +3% EV bet on a 42% side still loses 58% of the time, and the fair chance itself is an estimate. Closing line value over a large sample is the best evidence that the edge is real.
How can I tell if my bets had value, after the fact?: Compare the price you got with the closing line, the final price before the game started. Consistently getting better prices than the close (positive closing line value) is the strongest sign your process finds value, because the closing line is the market's most informed price. Wins and losses alone take hundreds of bets to separate skill from luck.

Information only: no price, finding or model guarantees a result. Bet only what you can afford to lose. 21+. If gambling is causing you harm, call or text 1-800-GAMBLER. More from Learn

1.Turn the price into a break-even chance

2.Remove the vig to find the fair price

3.Compare that fair price with every book

4.Size it to the edge, not to your confidence

5.Check the closing line afterwards

Where the Lab does this

Common questions

More from Learn