American odds show how much you win on a $100 bet, or how much you need to bet to win $100. A plus number like +150 is the profit on a $100 stake. A minus number like -110 is what you stake to win $100. Minus means favorite. Plus means underdog.
Minus odds: the favorite
-135 means you stake $135 to win $100. If it wins, you get back $235: your $135 stake plus $100 profit. The bigger the minus number, the bigger the favorite.
Plus odds: the underdog
+150 means a $100 stake wins $150. If it wins, you get back $250. The bigger the plus number, the bigger the underdog.
Implied probability
Every price hides a percentage: the chance the book is implying. For minus odds, divide the odds by the odds plus 100. For plus odds, divide 100 by the odds plus 100.
| Odds | Implied probability | Profit on $100 |
|---|---|---|
| -200 | 66.7% | $50 |
| -135 | 57.4% | $74.07 |
| -110 | 52.4% | $90.91 |
| +100 | 50.0% | $100 |
| +150 | 40.0% | $150 |
| +240 | 29.4% | $240 |
If you think a side wins more often than its implied probability, the price may be worth a look. That gap is the whole game.
The juice, or vig
When both sides of a spread are -110, each implies 52.4%. Together that is 104.8%, not 100%. The extra 4.8% is the book's margin, called the juice or vig. It is why you need to win about 52.4% of -110 bets just to break even.
Converting to decimal odds
Decimal odds show the total return per $1, stake included. For plus odds, divide by 100 and add 1. For minus odds, divide 100 by the odds (without the minus) and add 1.
| American | Decimal |
|---|---|
| -110 | 1.91 |
| -135 | 1.74 |
| +100 | 2.00 |
| +150 | 2.50 |
Reading a full betting line
Spread: Road Dogs +3.5 (-110) / Home Favs -3.5 (-110). Moneyline: Road Dogs +150 / Home Favs -175. Total: Over/Under 44.5 (-110).
The spread says the Home Favs must win by 4 or more to cover, and the Road Dogs cover if they lose by 3 or less, or win. The moneyline is just who wins. The total is the combined score. See spread vs moneyline vs totals for more.
Key takeaways
- Minus odds: stake that much to win $100.
- Plus odds: win that much on $100.
- Every price implies a probability.
- The juice is why -110 needs 52.4% to break even.
Frequently asked questions
What does +150 mean in betting?
A $100 bet wins $150 in profit, for a total return of $250. It implies a 40% chance.
What does -110 mean in betting?
You stake $110 to win $100. It implies a 52.4% chance, which is also the break-even win rate.
How do I calculate implied probability?
Minus odds: odds divided by (odds + 100). Plus odds: 100 divided by (odds + 100).
Why are both sides of a spread -110?
The book builds its margin into both sides. The two implied probabilities add up to more than 100%, and the extra is the book's edge.
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