Why prediction market tools matter
Prediction markets price probability. Every contract you trade — on Kalshi, Polymarket or ForecastEx — has an implied probability baked into its price. The tools on this page convert raw contract prices into numbers humans can reason about: probabilities, expected value, payouts, ROI, edge and risk-adjusted size.
We built these because the same questions come up over and over in our editorial work: What does this price actually mean? Am I getting paid enough to take this risk? How does this compare to the sportsbook line on the same event? Each calculator answers one of those questions, with substantial educational context wrapped around it.
How to use these calculators
Start with the Implied Probability Calculator to translate any price into a probability. Move to the Profit Calculator to size up the payout. When you have your own view, plug it into the Market Edge Calculator to see whether the contract offers positive expected value at your estimate.
Prediction market learning center
- What is a prediction market? — A prediction market is an exchange where people trade contracts whose payouts depend on the outcome of a future event.
- How event contracts work — An event contract is a financial instrument that pays exactly one dollar if a specified event occurs, and zero otherwise.
- Are prediction markets legal in the US? — Federally regulated event contracts are legal in the United States. State-level treatment, especially of sports markets, is contested.
- Prediction markets vs sportsbooks: the vig gap explained — Both let you put money on a future outcome, but the mechanics, regulators and — critically — the built-in house margin differ in ways that compound heavily over time.
- Prediction markets vs options trading — If you understand options pricing, you already understand most of what makes prediction market prices move.