Lesson 1 of 12 · 5 min read
What a bet is and how to read odds
American odds, implied probability, the vig, and why −110 means you need 52.4%.
A bet is a simple deal. You put up a stake. If your side wins, you get your stake back plus a payout set by the price. If it loses, the stake is gone. If the result lands exactly on the number, it’s a Glossary Push The result lands exactly on the number, like a 7-point win on a −7 spread. It’s a tie: the stake comes back, no win or loss. Full glossary Lesson: Spreads , and you get your stake back.
Every football line has up to three parts: the side (which team, or over/under), the number (a spread or total) and the price (the odds). This lesson is about the price.
Reading American odds
US sportsbooks show Glossary American odds The +/− price on a bet. A minus number (−150) is what you risk to win 100; a plus number (+130) is what you win if you risk 100. In units: −150 means risk 1.5u to win 1u. Full glossary . A minus sign means you risk more than you win. A plus sign means you win more than you risk. We’ll use Glossary Unit (u) A standard bet size. Results are tracked in units, not money, so a record reads the same no matter how much anyone bets. +4u means four standard bets ahead. Full glossary Lesson: Bankroll & units instead of money, so it works at any budget.
−110 means risk 1.1u to win 1u. A win returns 2.1u: your 1.1u back plus 1u profit.
If a price were +150, you’d risk 1u to win 1.5u.
Odds are probabilities in disguise
Every price implies a win chance, called Glossary Implied probability The win chance a price implies. −110 implies 52.4%; +150 implies 40%. Because of the vig, both sides of a bet add up to a bit more than 100%. Full glossary . Two quick formulas (ignore the sign when you plug in the number):
So −110 says “about 52.4%,” and +150 says “about 40.0%.”
The vig: the book’s cut
Notice both sides of the Hawks-Owls spread cost −110. If it were a true coin flip with no cut, both would be +100 (risk 1u to win 1u). The difference is the Glossary Vig (juice) The sportsbook’s built-in cut. It’s why both sides of a spread are usually −110 instead of +100: you risk 1.1u to win 1u. Full glossary , also called juice.
Add both sides: 52.4% + 52.4% = 104.8%. The extra 4.8% over 100% is the book’s margin.
Picture one person betting each side, 1.1u apiece. The book takes in 2.2u and pays the winner 2.1u. It keeps 0.1u, about 4.5% of everything bet, no matter who wins.
Why you need 52.4%, not 50%
Because you risk 1.1u to win 1u at −110, winning half your bets loses money. The Glossary Break-even rate The win rate you need to finish at zero units. At −110 it’s 52.4% (110 ÷ 210). Winning half your bets at −110 loses money. Full glossary is 52.4%.
That thin gap between 52 and 53 wins is why picking winners is hard, and why a record without the price attached tells you very little.
Quick checkAt +150, what win rate do you need to break even?Tap to see the answer
40.0%. 100 ÷ (150 + 100) = 0.40. If your side wins more often than 40% of the time at +150, you’re ahead over the long run. Less often, you’re behind.
Key takeaways
- A minus price means risk more than you win; a plus price means win more than you risk.
- Every price implies a win chance. −110 implies 52.4%.
- The vig is the book’s cut, about 4.5% on a standard −110 bet.
- At −110 you must win 52.4% of decided bets just to break even. Going 50-50 loses.
Info, not advice. Examples use made-up teams and lines. 21+ | Gambling problem? Call 1-800-GAMBLER.