Prediction market fee calculator
Enter a contract price and the number of contracts. The calculator shows Kalshi’s taker fee and the Polymarket fee for a given rate, in total and per contract.
How it works
Kalshi charges takers about 7% × price × (1 − price) per contract, and rounds the order’s fee up to the next cent. The fee peaks at 50¢ contracts and falls toward zero at the extremes. Polymarket applies a market-specific rate on the same curve, and many of its sports markets charge no taker fee.
Fees matter most when comparing venues. A 2-cent gap on a 50¢ contract can be nearly wiped out by Kalshi’s 1.75¢ fee. Courtside subtracts these fees before showing any edge on its board.
Common questions
How much is the Kalshi fee?
About 7% of price × (1 − price) per contract, rounded up to the cent per order. On 100 contracts at 50¢ that is $1.75.
Does Polymarket charge fees on NBA games?
Some sports markets have a taker fee and many do not. Enter the market’s rate, or 0 for a fee-free market.
Are maker orders cheaper?
Resting (maker) orders often have lower or no fees on both venues. This calculator shows taker fees for orders that fill immediately.
Why does the fee peak at 50¢?
The fee formula uses price × (1 − price), which is largest at 50¢ and smallest near 1¢ or 99¢.