American Odds Explained: How to Read + and - Odds
American odds use plus and minus signs to indicate underdogs and favorites. Here's exactly how to read them.
By
Eric Pauly
Feb 6, 2026
0 min read
What Are American Odds?
American odds, also called moneyline odds, are the standard format used by U.S. sportsbooks. They use plus (+) and minus (-) signs to indicate underdogs and favorites. Positive odds show how much profit you'd make on a $100 bet. Negative odds show how much you need to bet to win $100 profit. Once you understand this framework, you can quickly evaluate any bet at any sportsbook.
The American odds system might seem confusing at first compared to decimal odds, but it becomes intuitive with practice. The key insight is that the odds tell you two things simultaneously: your potential payout and the sportsbook's implied probability of that outcome occurring. When I first started betting, I focused only on payouts and ignored implied probability entirely. That changed when I realized that understanding probability is what separates betting from gambling. This guide explains how American odds work, how to calculate payouts and probabilities, and how to convert between odds formats.
article Summary
American odds use + for underdogs (profit on a $100 bet) and - for favorites (amount to bet for $100 profit). Larger positive numbers mean bigger underdogs with higher payouts. Larger negative numbers mean heavier favorites requiring larger bets. Every odds line implies a probability, and comparing that to your own assessment reveals whether a bet has value.
Understanding Positive and Negative Odds
Positive Odds (+)
Positive odds appear on underdogs and indicate profit per $100 wagered. If a team is +200, a winning $100 bet returns $300 total ($200 profit plus your $100 stake). If they're +350, a $100 bet returns $450. The higher the positive number, the less likely the sportsbook thinks that outcome is. Underdogs can also be slight underdogs (like +110) or massive longshots (+1000 or higher for futures).
Negative Odds (-)
Negative odds appear on favorites and indicate how much you must bet to win $100 profit. At -150, you'd bet $150 to win $100 profit (total return $250). At -300, you'd bet $300 to win $100 profit. The larger the negative number, the heavier the favorite. Betting favorites requires more capital for smaller returns because the outcome is considered more likely. Standard spread bets often carry -110 on each side, meaning you risk $110 to win $100.
Even Money
When odds are listed as +100 or "EVEN," you're getting a 1:1 payout. Bet $100, profit $100. This implies a 50/50 outcome before accounting for the vig. True coin-flip situations rarely appear at exactly +100 at sportsbooks because they need their margin. You'll typically see -105/-105 or -110/-110 splits on 50/50 markets, with the vig built into both sides.
Calculating Payouts
Positive Odds Payout Formula
For positive odds, multiply your stake by (odds/100). At +200, a $50 bet pays $50 x (200/100) = $100 profit. Add your stake for total return: $150. This formula works for any stake and any positive odds. Quick mental math: divide the odds by 100 to get your profit multiplier. +150 means you win 1.5x your bet. +250 means you win 2.5x your bet.
Negative Odds Payout Formula
For negative odds, divide your stake by (odds/100). At -150, a $75 bet pays $75 / (150/100) = $50 profit. Total return: $125. Alternatively, multiply your stake by (100/absolute odds). At -200, a $100 bet pays $100 x (100/200) = $50 profit. Quick mental math: at -200, you win half your bet. At -400, you win a quarter of your bet.
Using Betting Calculators
Most sportsbook apps calculate payouts automatically when you enter your stake. For complex bets or comparisons, standalone betting calculators let you input odds and see exact payouts. These are especially useful when shopping lines because you can quickly see how different odds translate to different returns. Betting tools with odds comparison features often include built-in calculators.
Implied Probability
What Is Implied Probability?
Every odds line implies a probability of that outcome occurring. The sportsbook isn't predicting exact percentages, but their odds translate to implied likelihoods. Understanding this helps you evaluate whether the odds offer value. If you think a team has a 60% chance of winning but the odds imply only 50%, you've found a potential edge.
Calculating Implied Probability
For negative odds: absolute value / (absolute value + 100). At -200: 200/(200+100) = 66.7%. For positive odds: 100 / (odds + 100). At +200: 100/(200+100) = 33.3%. These formulas give you the break-even win rate needed for the bet to be profitable. If you can win more often than the implied probability, you have positive expected value.
The Vig in Implied Probability
When you add the implied probabilities of both sides, the total exceeds 100%. A -110/-110 market implies 52.4% on each side, totaling 104.8%. The 4.8% overround is the vig, the sportsbook's built-in edge. Sharp sportsbooks might have 2-3% overround; recreational books might have 5-10% on less popular markets. Understanding this helps you identify when you're being charged too much. Our vig explanation covers this in depth.
Converting Between Odds Formats
American to Decimal
For positive American odds: (American / 100) + 1. +200 becomes (200/100) + 1 = 3.00 decimal. For negative American odds: (100 / absolute American) + 1. -200 becomes (100/200) + 1 = 1.50 decimal. Decimal odds show total return per unit staked, making them simpler for parlay calculations and quick comparisons.
Decimal to American
If decimal odds are 2.00 or higher: (decimal - 1) x 100 = positive American. 3.00 becomes (3-1) x 100 = +200. If decimal odds are below 2.00: -100 / (decimal - 1) = negative American. 1.50 becomes -100 / (1.50-1) = -200. Most odds comparison tools let you toggle between formats, but knowing the conversion helps when switching between U.S. and international sportsbooks.
American to Fractional
Positive American odds can be expressed as the odds number over 100, then reduced. +200 is 200/100 = 2/1. +150 is 150/100 = 3/2. Negative odds are 100 over the absolute value. -200 is 100/200 = 1/2. Fractional odds are less common in online betting but still appear in horse racing and UK markets.
Final Thoughts
American odds are the native language of U.S. sports betting. Once you're fluent, you can instantly evaluate any bet, calculate potential payouts, and assess whether the implied probability matches your analysis. The plus and minus signs become intuitive: bigger positives mean bigger underdogs with bigger payouts, and bigger negatives mean heavier favorites requiring larger stakes.
The real skill isn't just reading odds. It's using them to find value. Every bet is a comparison between the sportsbook's implied probability and your own assessment. When those differ in your favor, you have an opportunity. Use odds comparison tools to shop across sportsbooks and find the best prices. And remember that understanding odds is just the foundation. Applying that knowledge through expected value thinking is what turns reading odds into profitable betting.
American Odds FAQ
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