What Are American Odds (Moneyline Odds)?
American odds are characterized by a plus sign (+) or a minus sign (–), followed by a number that is usually in the hundreds, such as +150 or -200. These odds use a baseline of $100 to define the potential payout or the required stake.
The plus or minus sign immediately tells you which side the sportsbook expects to win:
- Negative Odds (–): The Favorite. This team is expected to win. The negative number shows you how much money you must risk to profit $100.
- Positive Odds (+): The Underdog. This team is expected to lose. The positive number shows you how much money you will win in profit for every $100 you bet.
In all cases, if your bet wins, you get your original bet amount (the stake) back, plus the profit.
The Favorite (The “–” Sign)
When you see a negative number like -150, it means:
- You must bet $150 to get a profit of $100.
- If your bet wins, your total return is $250 ($150 original stake + $100 profit).
A bigger negative number, such as -400, signals a stronger favorite. You have to risk $400 just to win $100. Because this outcome is considered more certain, you must risk more money to win a set amount.
The Underdog (The “+” Sign)
When you see a positive number like +200, it means:
- A $100 bet will win you $200 in profit.
- If your bet wins, your total return is $300 ($100 original stake + $200 profit).
A bigger positive number, such as +500, signals a bigger underdog. You win more money because the outcome is less likely.
Example in Action
Imagine an NBA game with the following Moneyline odds:
| Team | Odds | Analysis |
|---|---|---|
| Miami Heat | -390 | Favorite. Must risk $390 to win $100. |
| Philadelphia 76ers | +310 | Underdog. Win $310 on a $100 bet. |
This example shows the Heat are heavy favorites. The total gap between the numbers indicates how confident the book is in the favorite. A closer matchup might look like -120 vs. +100, suggesting a tight, nearly even contest.
How to Calculate Payouts with American Odds
The $100 baseline is just a reference point. You can place a bet for any amount, and the same ratio of risk-to-reward will apply.
1. Calculating Payouts for Underdogs (Positive Odds)
The formula finds your profit by figuring out the odds’ value relative to $100 and scaling it by your stake.
Total Payout = Profit + Stake
Example: You bet $50 on an outcome at odds of +150.
Profit = (150 / 100) × $50 = $75.
Total Payout = $75 (Profit) + $50 (Stake) = $125.
2. Calculating Payouts for Favorites (Negative Odds)
For negative odds, you must use the absolute value of the odds (ignore the minus sign). The formula calculates the profit using the required stake-to-win ratio.
Total Payout = Profit + Stake
Example: You bet $50 on a team at odds of -150.
Profit = (100 / 150) × $50 ≈ $33.33.
Total Payout = $33.33 (Profit) + $50 (Stake) ≈ $83.33.
You risked $50 on the favorite and only profited a fraction of that amount, which is typical for a likely winner.
Odds as Likelihood: Implied Probability
Odds do more than just set a price; they express the Implied Probability of an outcome. This is the chance the event needs to happen for the sportsbook to break even in the long run. By converting the odds to a percentage, you can see the bookmaker’s assessment of likelihood.
Implied Probability Formulas
| Odds Type | Formula | Example: Odds of -200 | Example: Odds of +200 |
|---|---|---|---|
| Negative (Favorite) | (|Odds| / (|Odds| + 100)) × 100% | (200 / (200 + 100)) × 100% = 66.7% | N/A |
| Positive (Underdog) | (100 / (Odds + 100)) × 100% | N/A | (100 / (200 + 100)) × 100% = 33.3% |
Understanding implied probability is essential because it allows you to compare your own assessment of a game to the sportsbook’s odds. If you think the underdog at +200 (implied 33.3%) actually has a 40% chance to win, you have found a bet with potential value.
The House Edge (The “Vig” or “Juice”)
If you calculate the implied probability for both sides of a contest and add them up, the total will almost always be more than 100%.
Example: A typical Point Spread bet often has odds of -110 on both sides.
- Side A (-110): ≈ 52.38%
- Side B (-110): ≈ 52.38%
- Total: 52.38% + 52.38% = 104.76%
That extra 4.76% is the sportsbook’s built-in commission, known as the vigorish or vig (often called juice). It is how the sportsbook guarantees a profit regardless of the game’s outcome. The vig is why you have to risk $110 to win $100 on a standard 50/50 bet. To break even at -110 odds, you must win at least 52.38% of your bets over time.
Point Spreads and Totals: Pricing at -110
While Moneyline bets (betting on who will win the game outright) have widely varying odds like -390 or +310, other popular bet types often use the standard -110 line.
Point Spreads
A point spread is a handicap that balances the matchup between two teams. You are betting on the margin of victory.
- Dallas Cowboys -7.5 (must win by 8 points or more)
- New York Giants +7.5 (must lose by 7 points or less, or win outright)
The odds for both sides of a standard spread are usually -110. This is the price you pay for taking either side of the spread, making it a 50/50 bet, with the vig included.
Totals (Over/Under)
A totals bet involves wagering whether the combined score of both teams will be Over or Under a specific number set by the sportsbook.
- Over 45.5 Points
- Under 45.5 Points
Like point spreads, the odds for both the Over and Under are almost always priced at -110.
Other Odds Formats: Decimal and Fractional
While American odds dominate the US market, two other formats are used globally. They all represent the exact same probabilities and payouts; they just display the numbers differently.
1. Decimal Odds (European Style)
The number represents the total payout (profit plus original stake) for every $1 wagered.
Profit = Total Payout – Stake
- 2.00 is Even Money.
- Favorites are always below 2.00 (e.g., 1.50).
- Underdogs are always above 2.00 (e.g., 3.00).
2. Fractional Odds (British Style)
Used often in the UK and in horse racing, the format X/Y means you win X units of profit for every Y units staked.
- 5/1 is an underdog (win $5 profit for every $1 bet).
- 1/2 is a favorite (win $1 profit for every $2 bet).
- 1/1 (or Evens) is Even Money.
Odds Conversion Table
The following table shows how these three formats align, which proves they are simply different ways of writing the same mathematical value.
| American (Moneyline) | Decimal | Fractional | Implied Win Probability |
|---|---|---|---|
| -200 | 1.50 | 1/2 | 66.7% |
| -150 | 1.67 | 2/3 | 60.0% |
| -110 | 1.91 | 10/11 | 52.4% |
| +100 (Even) | 2.00 | 1/1 (Evens) | 50.0% |
| +150 | 2.50 | 3/2 | 40.0% |
| +200 | 3.00 | 2/1 | 33.3% |
Conclusion
Reading American odds requires only a few simple rules: “–” means favorite (risk amount to win $100), and “+” means underdog (win amount on a $100 bet).
You now have the tools to:
- Instantly identify the favorite and underdog in any matchup.
- Calculate your exact payout for any bet size using the formulas.
- Understand the implied probability, which tells you the likelihood of the event.
- Recognize the standard -110 pricing for Point Spreads and Totals, along with the hidden cost of the vig.
With this knowledge, you can confidently interpret the lines on any US sportsbook and start placing informed wagers. Remember that successful betting is not just about picking winners; it is also about finding value where the implied probability is lower than your own assessed likelihood. Always bet responsibly, and enjoy the games!