What Does + and - Mean in Betting? Plus/Minus Odds Explained
Understanding Plus (+) and Minus (-) in American Odds
American odds are the standard odds format used by US sportsbooks. They're built around $100 as the base unit โ but you can bet any amount. The plus and minus signs tell you two things: which side is favored and what the potential payout is.
What the Minus (-) Means
The minus sign indicates the favorite. The number tells you how much you need to bet to win $100 in profit.
The larger the minus number, the bigger the favorite. -300 means the team is heavily favored โ you risk $300 to win $100.
What the Plus (+) Means
The plus sign indicates the underdog. The number tells you how much profit you win on a $100 bet.
The larger the plus number, the bigger the underdog. +500 means the team is a big underdog but pays 5x your stake.
Converting Plus/Minus to Probability
Every set of odds implies a probability โ how likely the sportsbook thinks the outcome is.
For minus odds:
Probability = Odds / (Odds + 100)
Example: -150 โ 150 / (150 + 100) = 60%
For plus odds:
Probability = 100 / (Odds + 100)
Example: +200 โ 100 / (200 + 100) = 33.3%
Understanding implied probability helps you evaluate whether odds offer value. If your analysis suggests a team has a 50% chance but the odds imply 40%, that's a value bet.
Use our odds converter for instant calculations โ
Real-World Examples
NFL Example: Chiefs -175 vs Bills +150. The Chiefs are 1.75x favorites. Implied: Chiefs 63.6%, Bills 40%. The combined implied probability exceeds 100% (103.6%) โ that gap is the sportsbook's profit margin (vigorish).
NBA Example: Celtics -110 vs Lakers -110. Both at -110 means the point spread is set to be a coin flip. You risk $110 to win $100 on either side.
MLB Example: Yankees +130 vs Astros -150. The Astros are moderate favorites. But Yankees +130 pays $130 profit on $100 โ meaning the sportsbook sees this as a competitive game.
Key Odds Numbers to Know
-110: The standard line. Most ATS and total bets use this.
-100 / +100 (Even money): True 50/50. Rare but exists.
+100 to +150: Slight underdog. Good value territory.
-200+: Heavy favorite. Low reward, high risk.
+300+: Big underdog. High reward, low probability.
How Our AI Uses Odds
Our AI models calculate their own probability for every outcome, independent of sportsbook odds. When our probability is HIGHER than the implied probability from the odds, that's where value lives.
For example, if our model says the Bills have a 45% chance of covering +3.5 but the +150 odds imply only 40%, that's a +5% edge โ a value bet.