Calculator
American ↔ Decimal ↔ Fractional ↔ Implied Probability
Every sportsbook displays prices differently. This converter translates American odds (e.g. -110 or +150) into decimal, fractional, and the raw win probability baked into the price — instantly.
The implied probability is the win chance the price encodes before the book's cut. Compare it to your own estimate to judge whether a bet has value.
Check a market's vig →Favorites are negative (e.g. -150), underdogs are positive (e.g. +130)
How this works
Formula
decimal = 1 + (american/100 if american>0 else 100/|american|) ; implied = 1/decimal
Worked example
+150 → 2.50 decimal → 3/2 fractional → 40% implied probability.
FAQ
What does -110 actually mean?
-110 means you must risk $110 to win $100. Decimal: 1.91. Implied probability: 52.38%.
How do I convert fractional odds?
Decimal = numerator/denominator + 1. So 5/2 = 2.50 + 1 = 3.50 decimal, or +250 American.
Why is implied probability higher than 50% on a -110 favorite?
Because the book bakes vig into both sides. Two -110 prices sum to 104.76% implied — the extra 4.76% is the book's hold.
What about pick'em (+100)?
+100 is even money: 2.00 decimal, 1/1 fractional, 50% implied probability.
Do these conversions work for in-play odds?
Yes — the math is identical for pre-game and live odds; only the price changes.