Odds Converter
Instantly convert betting odds between American, decimal, and fractional formats with implied probability.
Understanding Betting Odds Formats
Sports betting odds come in three main formats, and different regions, sportsbooks, and platforms default to different presentations:
American Odds (Moneyline): Used primarily in the United States. Positive numbers (e.g., +150) indicate the profit on a $100 bet. Negative numbers (e.g., -200) indicate how much you need to bet to profit $100. A +150 bet pays $150 profit on a $100 wager.
Decimal Odds: Popular in Europe, Australia, and most international sportsbooks. The number represents the total return per $1 wagered (including your stake). Decimal 2.50 means a $1 bet returns $2.50 total ($1.50 profit + $1.00 stake).
Fractional Odds: Traditional in the UK and Ireland. Expressed as a fraction like 3/2, meaning you profit $3 for every $2 wagered. The denominator is your stake and the numerator is your profit.
Why Odds Conversion Matters
Being fluent in all three formats is essential for comparing lines across sportsbooks. If one book shows +160 and another shows 2.50, are they the same? (No — +160 is 2.60 in decimal, which is better.) Without quick conversion, you can miss value or make incorrect comparisons.
Odds conversion also unlocks implied probability — the probability a bet needs to win at to break even. This is the foundation of value betting. If a book offers +200, the implied probability is 33.3%. If you believe the true probability is 40%, you have found a +EV opportunity.
Our converter handles all three formats in both directions and instantly shows the implied probability for any odds value.
Implied Probability Explained
Implied probability converts odds into a percentage that represents what the sportsbook's pricing assumes is the chance of that outcome happening. Every set of odds has an implied probability.
The catch is that implied probabilities in a market always sum to more than 100% because of the bookmaker's margin (vig). In a fair coin flip, each side should be 50%. But a sportsbook might price it at -110 on each side, giving each outcome an implied probability of 52.4% — totaling 104.8%. That extra 4.8% is the vig, the sportsbook's built-in edge.
Understanding implied probability is the first step toward finding value bets. If you can accurately estimate the true probability of an outcome and compare it against the implied probability, you can identify profitable betting opportunities.
Worked Example: Comparing Lines Across Sportsbooks
Sportsbook A offers +145 (American), Sportsbook B offers 2.40 (decimal), and Sportsbook C offers 7/5 (fractional) on the same outcome. Which offers the best value?
- Sportsbook A: +145 American → Decimal: 2.45 → Implied prob: 40.82%
- Sportsbook B: 2.40 Decimal → American: +140 → Implied prob: 41.67%
- Sportsbook C: 7/5 Fractional → Decimal: 2.40 → American: +140 → Implied prob: 41.67%
- Sportsbook A offers 2.45 decimal odds (best payout per dollar)
- Sportsbooks B and C are identical at 2.40 decimal
- The difference: $5 more profit per $100 bet at Sportsbook A
Sportsbook A offers the best value at +145 / 2.45 decimal. The 0.05 decimal odds difference means $5 extra profit per $100 wagered. Over hundreds of bets, choosing the best line consistently compounds into significant additional profit.
Frequently Asked Questions
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