Prediction Market Payout & Edge Calculator
Enter a Yes price and your stake to instantly see your shares, payout, profit, and implied probability. Add your own probability estimate and the calculator tells you whether the bet has positive expected value — the one number that separates informed trading from guessing.
How the math works
Three rules cover everything. One: shares = stake ÷ price. Two: every winning share pays $1, losing shares pay $0. Three: price in cents = the market's probability in percent. So $50 at 25¢ buys 200 shares. If the event happens you collect $200 ($150 profit, a 4x return). If it doesn't, the $50 is gone. The market is telling you it believes there's a 25% chance — the full logic is in how to read prediction market prices.
What "edge" means in one sentence
Edge is the gap between your honest probability estimate and the market's price: believe 40% when the market prices 25% and you have a 15-point edge; believe 25% when the market prices 25% and you have none — then the bet is a coin-flip minus fees, which is gambling, not trading. Academic research on market calibration (Iowa Electronic Markets, operating since 1988) shows prices are close to true frequencies on average, so beating them takes real information, not vibes.
Numbers are the easy part. Judgment is the game.
Polywise drills this calculator's logic as a game: real market prices, your estimate, instant feedback on whether you had an edge. Free, no account, no deposit.
Practice edge-spotting free on Polywise →Frequently asked questions
How do I calculate my payout on a prediction market?
Divide your stake by the share price to get your number of shares; each winning share pays $1. Example: $50 at a 25¢ Yes price buys 200 shares, which pay $200 if Yes wins — a $150 profit. If Yes loses, you lose the $50.
What is implied probability in a prediction market?
The share price read as a percentage. A 25¢ Yes price implies the market collectively estimates a 25% chance the event happens. Price and probability are the same number in different clothes.
What is expected value (EV) on a prediction market bet?
Your average result if the same bet were repeated many times: (your probability × profit if right) minus ((1 − your probability) × stake). A bet is +EV only when your honest probability estimate is higher than the price. Buying at 25¢ when you believe the true chance is 40% is +EV; buying at 25¢ when you also think 25% is break-even minus fees.
Does this calculator work for both Polymarket and Kalshi?
Yes. Both platforms use prices between 1¢ and 99¢ where winning shares settle at $1, so the same math applies. Fees differ by platform and are not included — check each platform's fee page.
Where can I practice using these numbers before betting real money?
Polywise turns this exact math into free game-like drills using real market examples — no account or deposit. Rehearse edge and expected value until it's reflex, then decide whether to trade for real.