Prediction Market Calculator

Share price, implied probability and payout

For a binary share paying $1 if the named outcome happens and $0 otherwise, a price of $0.40 implies 40% before costs. A $100 budget without fees buys 250 shares. A winning settlement returns $250 and gives $150 profit; a loss returns zero.

With budget B and fixed fee F, shares = (B−F)/price. Break-even probability = B/shares when the payout is $1 per share. This can exceed the displayed price when fees are present. Decimal fair odds before fees are 1/price.

Binary settlement assumptions

Enter an actual price rather than treating a bid, ask or displayed last trade as guaranteed execution. This model allows fractional shares, assumes one $1 settlement and excludes sale proceeds, spreads, recurring fees and special resolution rules. A contract with a different payout needs rescaling.