Both formats encode the same probability. The difference is how they express it — and which one your brain finds most natural for quick calculations.
Last updated June 2026
| Property | Decimal | American |
|---|---|---|
| Even money | 2.00 | –100 / +100 |
| Heavy favourite | 1.25 | –400 |
| Strong favourite | 1.50 | –200 |
| Slight favourite | 1.80 | –125 |
| Slight underdog | 2.20 | +120 |
| Strong underdog | 3.50 | +250 |
| Long shot | 11.00 | +1000 |
| Return formula | Stake × odds | +(American/100×stake) or −(100/|American|×stake) |
| Includes stake in display | Yes | No |
| Common regions | Europe, Australia, Asia | USA, Canada |
| Calculation ease | High | Moderate |
If decimal ≥ 2.00: American = (decimal − 1) × 100
Example: 3.50 → (3.50 − 1) × 100 = +250
If decimal < 2.00: American = −100 ÷ (decimal − 1)
Example: 1.50 → −100 ÷ (1.50 − 1) = −100 ÷ 0.50 = –200
Positive American: decimal = (American ÷ 100) + 1
Example: +200 → (200 ÷ 100) + 1 = 3.00
Negative American: decimal = (100 ÷ |American|) + 1
Example: –150 → (100 ÷ 150) + 1 = 1.667
Use decimal if: you want faster mental maths, you're outside North America, or you're comparing prices across different bookmakers. Decimal is objectively simpler for calculating returns and implied probability.
Use American if: you're betting on US sports through American-facing books, or you're reading US sports media coverage. Most US sportsbooks default to American odds, and the format is baked into how US betting culture discusses lines ("the spread at –110").
Decimal → probability: 1 ÷ decimal_odds
Example: 2.50 → 1 ÷ 2.50 = 40%
American (positive) → probability: 100 ÷ (American + 100)
Example: +150 → 100 ÷ 250 = 40%
Both give the same result. Use our odds converter tool to switch between all 7 formats instantly.