Implied Probability Calculator
Convert a contract price to implied probability and break-even win rate. Works with any prediction market — Kalshi, Robinhood, or Polymarket.
What implied probability means
On prediction markets, contract prices range from $0.01 to $0.99. A YES contract priced at $0.65 means the market collectively estimates a 65% chance the event resolves YES.
That price is the implied probability — no conversion needed. The market prices and the probability are the same number.
Break-even win rate
To profit long-term, your actual win rate must exceed the market's implied probability. If a contract trades at 65¢, you need to win more than 65% of the time on similar bets to show positive expected value.
This calculator shows both. If you have genuine information edge — you believe the true probability exceeds the market price — the Kelly criterion calculator helps you size that edge correctly.
The formula
Profit if YES = ($1.00 − price) × contracts
Loss if NO = price × contracts
How to read this on Kalshi
Kalshi displays YES prices in cents. A market showing 65 means $0.65 per contract. Buy 100 contracts for $65. If it resolves YES, you receive $100 — a $35 profit.
The bid/ask spread adds friction. The true implied probability sits between the best bid and best ask, not at either edge.
Ready to trade prediction markets?
Kalshi offers CFTC-regulated event contracts with no trading fees. Robinhood lets you trade the same markets inside an account you may already have.