Free tool

Expected Value Calculator

Estimate the value of a Yes or No prediction-market contract using your own probability and the price you can buy at.

Contract sideBuy price, cents per Yes contractYour probability that Yes wins, %Estimated all-in costs, cents per contractNumber of contracts

Estimated EV per contract

$0.06

Estimated total EV

$6.00

Break-even probability

54.0%

Maximum loss at settlement, estimated

$54.00

If your forecast is 5 percentage points too high

At 55.0% probability, total expected value becomes $1.00. Winning nets $46.00; losing costs $54.00.

Illustrative stress test. This does not estimate the reliability of your forecast.

Assumes a binary contract pays $1 for a win and $0 for a loss, and entered costs are paid regardless of outcome. Your probability applies to the selected side. The calculator does not fetch a live quote or calculate venue-specific fees. If fees depend on the result, model each outcome separately. A positive EV can still lose the full purchase cost.

How to interpret the result

For a binary contract paying $1 when your chosen side wins, expected value per contract is your win probability minus the all-in cost. A 60% estimate and a 52¢ buy price plus 2¢ in costs gives an estimated 6¢ of EV per contract. The break-even probability is 54%.

Use the actual executable quote for your order size. Recheck fees and settlement rules at the venue. A small positive result is especially sensitive to forecast error and slippage.

Read the full expected value guide for worked examples and risk checks. Use the profit calculator for winning payout and maximum loss, or browse live market odds before entering a price.