FinanceCalcs
Betting Odds Calculator
Convert between American (+/−), decimal, and fractional odds formats instantly. See the implied probability, your potential payout, and profit on any bet size. Understanding odds is the foundation of smart sports betting.
American odds of −110 mean you must bet $110 to win $100. +150 means a $100 bet wins $150. Both express probability differently — this calculator shows all formats simultaneously.
Betting Odds Calculator
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Payout: $0 — Profit: $0
All Formats
Payout at Different Bet Sizes
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Odds Comparison — Same Bet Size
| American | Decimal | Fractional | Implied % | Profit on $100 | Type |
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"The sportsbook doesn’t set odds based on who will win. They set odds to balance their book — and collect the vig regardless of the outcome."
— Sports Betting Fundamentals
Understanding the three odds formats
American odds (moneyline) are expressed as positive or negative numbers. Negative means favorite: −150 means bet $150 to win $100. Positive means underdog: +150 means bet $100 to win $150. The number always represents profit relative to a $100 stake for positives, or the stake needed to win $100 for negatives.
Decimal odds represent the total return per $1 wagered, including your stake. Odds of 2.50 mean a $1 bet returns $2.50 total ($1.50 profit). This is the most intuitive format for direct comparison — higher decimal odds always mean higher payout and lower implied probability.
Fractional odds (common in UK horse racing) show profit relative to stake. 5/2 means win $5 for every $2 bet. The implied probability is the denominator divided by the sum: 2/(5+2) = 28.6%.
Odds FAQs
What does −110 mean in betting?
−110 is the standard American spread bet line. You must bet $110 to win $100 profit. Total return = $210. The implied probability is 110/(110+100) = 52.38%. The extra 4.76% above 50% is the sportsbook’s vig — why both sides of a −110/−110 line sum to 104.76% rather than 100%.
How do you convert American to decimal odds?
For positive odds: decimal = (american/100) + 1. So +150 = 2.50. For negative odds: decimal = (100/|american|) + 1. So −150 = (100/150) + 1 = 1.667. Decimal odds always include the original stake in the return; American odds show only profit.
What is implied probability?
The win probability embedded in the odds. Decimal: 1/decimal. American positive: 100/(odds+100). American negative: |odds|/(|odds|+100). If you believe the true probability is higher than the implied probability, the bet has positive expected value.
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