How to read American odds: minus, plus and what they pay

Two signs, two questions

American odds — also called moneyline odds — are the default format at US sportsbooks. Every price has a sign and a number, and the sign tells you which question the number answers.

A minus sign (−150) tells you how much you must stake to win $100. A plus sign (+150) tells you how much you win on a $100 stake. Favorites usually carry a minus, underdogs a plus, and a price of +100 is even money: stake $100, win $100.

Reading a favorite: minus odds

At −150 you risk $150 to win $100. If the bet wins you get $250 back: your $150 stake plus $100 profit. For any stake, profit = stake × 100 ÷ 150. A $30 bet at −150 wins $20.

The bigger the number after the minus, the heavier the favorite and the less each dollar earns. At −300 you risk $300 to win $100.

Reading an underdog: plus odds

At +150 a $100 stake wins $150, returning $250 in total. For any stake, profit = stake × 150 ÷ 100. A $30 bet at +150 wins $45.

The bigger the number after the plus, the longer the shot and the more a win pays.

Converting to decimal odds

Decimal odds give the total return per $1 staked, stake included, and they make comparisons simple.

For plus odds: decimal = 1 + (odds ÷ 100). +150 becomes 2.50.

For minus odds: decimal = 1 + (100 ÷ |odds|). −150 becomes 1.667.

Decimal odds are also what you need for the expected value formula.

Converting to a probability

Every price implies a probability — the win rate at which the bet breaks even.

For minus odds: |odds| ÷ (|odds| + 100). −150 implies 150 ÷ 250 = 60%.

For plus odds: 100 ÷ (odds + 100). +150 implies 100 ÷ 250 = 40%.

The implied probabilities on both sides of a game usually add up to more than 100%. That extra is the sportsbook's margin, covered in our guide to implied probability.

Putting it to work

Knowing the implied probability lets you compare a price with a forecast. If a model gives a team a 60% chance and the best price is −130 (implied 56.5%), the price is asking less than the forecast suggests the outcome is worth. If the price is −170 (implied 63%), it is asking more.

That comparison — model probability against the best available price — is exactly what each row on the SharpDeck board shows, so you can see it without doing the arithmetic yourself.