Prediction market fees compared

How prediction market fees work

Prediction markets make money from fees on each trade rather than from a margin built into the odds. Three things decide what you pay:

• The price of the contract. Kalshi, Polymarket US and OG charge in proportion to price × (1 − price). That’s largest at 50¢ (0.5 × 0.5 = 0.25) and shrinks toward zero at 1¢ or 99¢, so trading a coin-flip costs the most and trading a near-certainty costs almost nothing.
• Whether you’re a taker or a maker. A taker fills an order that’s already in the order book; a maker places a limit order that waits until someone takes it. Exchanges want makers because they provide liquidity, so makers pay less.
• Whether you use a broker. Robinhood and Interactive Brokers pass on the exchange’s fee and may add their own commission.

The fees below are taken from each platform’s published schedule as of September 30, 2026. They’re the same fees we use to score the “fees & pricing” criterion in our ranking of the best US prediction markets.

Trading fees by platform

A few details worth knowing:

• Kalshi uses a fee schedule that took effect on July 7, 2026. Some series, such as certain elections, award shows and championships, carry different multipliers, and combo markets have their own maker multiplier. Cancelling a resting order is free.
• Polymarket US introduced its current schedule on September 25, 2026. Combos cost slightly more, and high-volume takers get 10–50% of their taker fees back, based on the previous month’s volume and paid weekly.
• Robinhood Gold ($5 a month) halves the commission constant from 10% to 5%, which matters for contracts priced far from 50¢.
• Interactive Brokers charges $0.01 commission plus $0.01 exchange fee on Kalshi and CME contracts it routes, but no commission on ForecastEx’s own contracts.

What 100 contracts cost

Buying 100 contracts as a taker (the fee on top of the purchase price):

Robinhood figures assume a Kalshi-listed contract; its own example — 100 contracts at 90¢ costing $91.90 all in, or $91.45 with Gold — matches the table.

Worked example

You think a team has a better than even chance and buy 100 “Yes” contracts at 50¢ on Kalshi as a taker:

1. Cost: $50.00 for the contracts plus a $1.75 fee = $51.75.
2. If the team wins: each contract pays $1, so you receive $100 — a profit of $48.25.
3. If the team loses: the contracts expire worthless and you lose $51.75.
4. If you sell early at, say, 70¢, you receive $70 minus the fee on that sale (0.07 × 100 × 0.7 × 0.3 = $1.47), so $68.53 back on your $51.75.

Deposit and withdrawal fees

Costs you won’t see in the fee schedule

• The spread. If the best price to buy is 52¢ and the best price to sell is 48¢, a round trip costs 4¢ before fees. Liquid markets on Kalshi and Polymarket US usually have tight spreads; thinner markets can be much wider.
• Unsettled cash. Robinhood only lets you use fully settled cash for event contracts, so a slow bank transfer can leave you waiting.
• Interest you give up — or earn. Kalshi pays a variable APY on cash and open positions for eligible accounts with at least $250 (3.25% according to its help center; one third-party source cites 3.75%). ForecastEx pays a 3.38% APY incentive coupon on positions, minus an administrative fee on the interest. The others don’t pay interest on positions.

Fees vs a sportsbook’s vig

Sportsbooks don’t charge a visible fee; they build a margin into the odds. At -110 on both sides of a game, each side implies a 52.4% chance, so the book keeps about 4.5% of the money bet.

On a prediction market, a fair 50/50 contract bought as a taker on Kalshi costs 51.75¢ for a $1 payout — the equivalent of about -107 in American odds. On ForecastEx it’s about -104, and if your limit order is filled as a maker on a fee-free Kalshi market you pay even money. You can check these conversions with our odds calculator and read more in prediction markets vs sportsbooks.

Treat odds conversions as a rough guide. The CFTC warned platforms in August 2026 that showing contract prices as sportsbook-style odds is likely to mislead, because the price you pay also depends on the spread and on fees. See how to read prediction market prices as odds.

How to keep fees down

• Use limit orders when you’re not in a hurry. On Kalshi most maker orders are free, and on Polymarket US makers earn a rebate.
• Fund by bank transfer. ACH is free on every platform we reviewed; cards and PayPal can cost up to 2% on Kalshi.
• Withdraw less often. Interactive Brokers gives you two free withdrawals a month, and instant withdrawals cost extra at Robinhood and OG.
• Consider Robinhood Gold only if you trade often on Robinhood, and compare it with trading the same Kalshi contract directly on Kalshi.

The bottom line

The headline trading fees at Kalshi, Polymarket US and OG are almost identical, so the real differences are maker pricing, payment fees and liquidity. Interactive Brokers is cheapest per contract but doesn’t list sports. For the full picture — fees, regulation, markets and availability — see our ranking of the best prediction markets in the US.