How much does Kalshi charge per trade?

Kalshi charges takers 0.07 × contracts × price × (1 − price), rounded up to the next cent. At 50¢ that is 1.75¢ per contract, the most it can be; at 10¢ or 90¢ it falls to about 0.63¢. S&P 500 and Nasdaq-100 markets use half the rate (0.035), and maker fees, where they apply, use 0.0175.

Does Polymarket charge trading fees?

Polymarket charges takers C × feeRate × p × (1 − p), where the rate depends on the market category: 0.07 for crypto, 0.05 for sports, economics, culture, weather and most others, 0.04 for politics, finance, tech and mentions, and zero for geopolitics. Makers pay no fee.

Why are fees highest at 50¢?

Both venues scale the fee by price × (1 − price), which peaks at 0.25 when the price is 50¢ and shrinks towards the extremes. A 30¢ and a 70¢ trade pay the same dollar fee.

What is the break-even probability?

It is the all-in cost per contract (price plus fee) as a share of the $1 payout. If you pay 40¢ plus 1.68¢ in fees, the contract has to win more than 41.68% of the time for you to profit.

Kalshi & Polymarket fee calculator

Enter a price and a number of contracts to see what Kalshi and Polymarket would charge, side by side. You also get the all-in cost, the profit if the contract wins, and the win rate you need to break even after fees.

Price per contract

The YES or NO price you are buying at

Contracts

Each contract pays $1 if it wins

Kalshi fee type

Polymarket category

Polymarket order

Kalshi

rate 0.07, rounded up to the cent

Fee

$1.68

Fee / contract

1.680¢

All-in cost

$41.68

Fee % of cost

4.20%

Profit if it wins

$58.32

Break-even prob.

41.68%

Polymarket

rate 0.04

Fee

$0.96

Fee / contract

0.960¢

All-in cost

$40.96

Fee % of cost

2.40%

Profit if it wins

$59.04

Break-even prob.

40.96%

Polymarket is cheaper on fees for this trade by $0.72.

How Kalshi fees work

Kalshi charges a trading fee on each fill, based on the contract price P in dollars and the number of contracts C:

fee = round_up(0.07 × C × P × (1 − P))

The fee is rounded up to the next cent per order, so very small orders pay a little more per contract. Markets on the S&P 500 and Nasdaq-100 use a 0.035 rate, and markets that charge makers use 0.0175. Source: Kalshi fee schedule.

How Polymarket fees work

Polymarket charges takers only, with a rate set by the market's category:

fee = C × feeRate × p × (1 − p)

Fees are rounded to five decimal places in USDC. Makers pay nothing and can earn rebates funded by taker fees. Source: Polymarket fee docs.

Fees and cross-venue arbitrage

An apparent arbitrage between Kalshi and Polymarket only exists if the YES price on one venue plus the NO price on the other, plus both fees, is under $1. Use this calculator for each leg, or see live gaps in the edge scanner.

Frequently asked questions

How much does Kalshi charge per trade?: Kalshi charges takers 0.07 × contracts × price × (1 − price), rounded up to the next cent. At 50¢ that is 1.75¢ per contract, the most it can be; at 10¢ or 90¢ it falls to about 0.63¢. S&P 500 and Nasdaq-100 markets use half the rate (0.035), and maker fees, where they apply, use 0.0175.
Does Polymarket charge trading fees?: Polymarket charges takers C × feeRate × p × (1 − p), where the rate depends on the market category: 0.07 for crypto, 0.05 for sports, economics, culture, weather and most others, 0.04 for politics, finance, tech and mentions, and zero for geopolitics. Makers pay no fee.
Why are fees highest at 50¢?: Both venues scale the fee by price × (1 − price), which peaks at 0.25 when the price is 50¢ and shrinks towards the extremes. A 30¢ and a 70¢ trade pay the same dollar fee.
What is the break-even probability?: It is the all-in cost per contract (price plus fee) as a share of the $1 payout. If you pay 40¢ plus 1.68¢ in fees, the contract has to win more than 41.68% of the time for you to profit.

More trader calculators

No-vig calculator

Strip the overround from a set of prices to get fair, vig-free probabilities.

EV calculator

EV, ROI, edge and Kelly stake from a contract price and your own probability.

Odds converter

Convert between cents, implied probability, American and decimal odds.

Calculations run in your browser and are estimates for education only, not financial advice. Venue fee schedules change; check the venue before you trade.