Tools
Free calculators to turn market prices into probabilities, profits and position sizes.
- Odds ConverterConvert a prediction-market price into implied probability, decimal, fractional and American odds — and back.
- Profit CalculatorSee your cost, profit if you win, loss if you lose and return on investment for any share price.
- Expected Value CalculatorCompare your own probability with the market price to estimate expected value per share and in total.
- Kelly CalculatorEstimate full, half and quarter Kelly position sizes from the price, your probability and your bankroll.
- Fee CalculatorEstimate trading fees by market category and order type (maker or taker).
- Country CheckerLook up a country to see whether Polymarket is listed as available, restricted or not yet verified.
Prediction market calculators
Our free odds calculator converts a Polymarket price into implied probability and decimal or American odds. The profit calculator and expected value calculator show cost, potential payout and EV per share, while the Kelly calculator helps with position sizing and bankroll management. Think of them as a paper-trading simulator for decisions: practise the maths before risking real money.