American vs Decimal Odds: Formats Explained and Converted
American odds (-110, +150) show profit relative to $100; decimal odds (1.91, 2.50) show total return per unit staked. Same probabilities, different notation - and decimal is far easier to calculate with.
American Odds
Negative numbers show stake needed to win $100; positive show profit on $100.
Pros
- Standard at all US sportsbooks
- Favorite/underdog status instantly visible
- Familiar to US bettors
Cons
- Two different formulas around +/-100
- Awkward for parlay math
- Implied probability isn't obvious
Decimal Odds
One number: total return per $1 staked, stake included.
Pros
- Parlays = multiply the decimals
- Implied probability = 1 / decimal
- One formula for all prices
Cons
- Less common at US books
- Favorite status less instantly readable
- Requires mental conversion for US bettors
The Verdict
Learn to think in decimal: parlay math is simple multiplication and implied probability is just 1/decimal. American odds remain the US display standard, so being fluent in both (or using a converter) is essential.
Frequently Asked Questions
How do I convert -110 to decimal odds?
For negative American odds: 1 + (100 / |odds|). So -110 becomes 1 + 100/110 = 1.91. For positive odds: 1 + odds/100, so +150 becomes 2.50.
Why do parlays use decimal odds?
Because the combined price is just the product of the legs' decimals. Three legs at 1.91 = 1.91^3 = 6.97 decimal (+597 American). Doing the same in American odds requires converting anyway.