Odds Converter & Implied Probability Calculator

Convert any odds format to a probability

Sportsbooks quote American (−110) or fractional (5/2) odds; exchanges use decimal (2.00); prediction markets like Polymarket use a price in cents that is really an implied probability. This converter turns any one of them into all the others instantly — so you can compare a sportsbook line to a Polymarket price in seconds.

The formulas

• Decimal → probability: 1 ÷ decimal (2.00 → 50%)
• American (+) → decimal: (odds ÷ 100) + 1 (+150 → 2.50)
• American (−) → decimal: (100 ÷ |odds|) + 1 (−200 → 1.50)
• Polymarket price: price in cents = implied probability (65¢ = 65%)

Why traders use it

The fastest way to spot value is to put every market in the same units — probability. Convert the sportsbook line, strip its margin with the no-vig calculator, then compare it to the live Polymarket price. If your own estimate beats the market, check whether the bet is +EV. Explore the full set of Polymarket analytics tools to automate the hunt.