Prediction Market Calculator

For Kalshi, Polymarket, and Robinhood Prediction Markets

Plan and evaluate your prediction market positions before you buy. Enter the cost and price for each contract on Kalshi, Polymarket, Robinhood, or any other prediction market platform. The calculator shows your potential payout and profit for each contract after fees, and tracks your total exposure across all positions. Check which predictions you actually made and which ones came in to see your real P&L.

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Cost ($) Price (0–1) Fee Payout Profit Correct?
Total Cost $0.00
Total Payout $0.00
Total Profit $0.00
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How the Calculator Works

Enter Your Contracts

Add a row for each position. Enter the total cost (how much you're spending), the price per share (e.g. 0.65 for a 65¢ contract), and the platform fee (defaults to 1%).

Payout Formula

Payout is calculated as (cost / price) × (1 − fee). This gives you your net return if the prediction resolves in your favor. Profit is payout minus your original cost.

Track Your Positions

Use the Made? checkbox to mark which contracts you actually purchased. Unchecked rows are excluded from total cost. Use the Correct? checkbox to mark which predictions came in, included in total payout.

Batch Operations

Click a row to select it, shift-click to select a range, or Ctrl/Cmd+click to add individual rows. Toggle a checkbox or edit the fee on any selected row to apply the change to all selected rows at once.