Probability ↔ odds converter
Enter an implied probability, decimal odds, or American odds. The tool converts between formats, rejects impossible values, and never stores your inputs.
Calculator
What this tool does
Prediction markets usually quote an implied probability (0–1 or 0–100%). Bookmakers and some APIs use decimal or American odds. This converter translates between those formats so you can compare quotes without mixing units.
Formulas
Probability `p` is in `0 < p < 1` (exclusive). Decimal odds `d = 1 / p`. American odds: if `p ≤ 0.5` then `american = 100 * (1 - p) / p` (positive); if `p > 0.5` then `american = -100 * p / (1 - p)` (negative).
Limits
Values outside open (0, 1) for probability, or non-positive decimal odds, are rejected. This is a unit converter, not a forecast, betting tip, or edge detector. Exchange prices still need observation timestamps from market pages before you quote them publicly.