Convert between formats
Type into any field — the others update automatically. All four represent the same price.
Remove the vig (two-sided market)
Sportsbook implied probabilities sum to more than 100% — the extra is the bookmaker's margin. Enter both sides to see the fair (no-vig) probability.
Quick reference
Common moneyline lines across all four formats.
| American | Decimal | Fractional | Implied |
|---|---|---|---|
| -250 | 1.40 | 2/5 | 71.4% |
| -200 | 1.50 | 1/2 | 66.7% |
| -150 | 1.67 | 4/6 | 60.0% |
| -110 | 1.91 | 10/11 | 52.4% |
| +100 | 2.00 | 1/1 | 50.0% |
| +110 | 2.10 | 11/10 | 47.6% |
| +150 | 2.50 | 3/2 | 40.0% |
| +200 | 3.00 | 2/1 | 33.3% |
| +400 | 5.00 | 4/1 | 20.0% |
| +650 | 7.50 | 13/2 | 13.3% |
How the conversions work
American to implied probability: If the line is negative, prob = -odds / (-odds + 100). If positive, prob = 100 / (odds + 100).
Decimal to implied probability: prob = 1 / decimal. Decimal 2.0 means 50% — a $1 bet returns $2 total ($1 stake + $1 profit).
Fractional to implied probability: prob = denominator / (numerator + denominator). So 10/11 means 11 / (10+11) = 52.4%.
The vig: Two-sided sportsbook lines almost never sum to 100% — they sum to 104-108%. The extra is the bookmaker's margin. Removing it (proportional normalization) gives the fair probability the book actually thinks each side has.
Prediction markets like Polymarket and Kalshi skip the vig entirely. The displayed price IS the implied probability, with no margin built in (other than a small explicit taker fee, typically 1-2%).
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