How to Read Betting Odds: + and - Explained

American betting odds use a plus or minus sign. A minus number (like -150) is the favorite and shows what you risk to win 100. A plus number (like +130) is the underdog and shows what 100 wins. The number also tells you the implied probability the book is charging.

Read the sign. Minus means favorite, plus means underdog. -150 risks 150 to win 100; +130 risks 100 to win 130.
Work out the payout. For a minus price, win = 100 x (100 / number). For a plus price, win = stake x (number / 100). A converter does this instantly.
Convert to probability. A -150 favorite implies about 60 percent; a +130 dog implies about 43 percent. The two sides add to more than 100 percent, and that gap is the vig.
Compare across books. Different books post different prices for the same bet. The best number is free money over time.

A worked odds example

You see Team A -150 and Team B +130. Betting 100 on A wins 66.67 (100 x 100/150) if they win. Betting 100 on B wins 130. A's implied probability is 150 / (150 + 100) = 60 percent; B's is 100 / (130 + 100) = about 43 percent. They sum to 103 percent, and that extra 3 percent is the book's built-in margin, the vig.

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Decimal and fractional odds

Outside the US you will see decimal (2.50 means your stake times 2.5 is returned) and fractional (5/2) odds. They describe the same thing as American odds in a different format. An odds converter switches between all three and shows the implied probability so you can compare any price.

Frequently asked questions

What does + and - mean in betting odds?

Minus marks the favorite and what you risk to win 100. Plus marks the underdog and what 100 would win. The size of the number reflects how likely the book thinks each side is.

How do I turn odds into a probability?

For a minus price: number / (number + 100). For a plus price: 100 / (number + 100). The two sides add past 100 percent because of the vig.

Keep going

Odds Converter →What do + and - mean? →What is the vig? →No-Vig Calculator →Understand how odds work →Start as a beginner →Find value bets →All betting guides →

21+. For entertainment and educational purposes, not financial advice. If gambling stops being fun, take a break. 1-800-GAMBLER. Regulated US books only.