Prediction market fees, compared across every venue
Fees on event contracts are not a flat commission. The venues that publish a schedule charge a quadratic fee: largest when a market is nearest a coin flip and falling towards either end, so the same trade costs more on an uncertain question than on a near-settled one. All 5 venues here publish a fee we can source, 2 of them a full formula; none is filled from memory.
Fee comparison table
| Venue | Model | Who pays | Source | |
|---|---|---|---|---|
| Kalshi | quadratic (6 variants) | taker; maker on some families | ✓ venue API | Detail |
| Polymarket | taker fee on most markets; makers pay nothing | taker only | venue docs | Detail |
| Robinhood | $0.01 to $0.02 per contract | – | – | Detail |
| DraftKings Predictions | up to $0.02 per contract | – | – | Detail |
| FanDuel Predicts | $0.02 per contract | – | – | Detail |
Venues without a published schedule are blank rather than filled from memory: a fee table is exactly the page where a confidently-wrong number costs a reader money.
The fee models explained
Quadratic: the fee scales with price × (1 − price), largest at 50¢ and smallest at the extremes. Polymarket states it as shares × rate × price × (1 − price) with the rate set per market category; Kalshi sets a model and a multiplier per contract family. Variants add a maker fee (charged to resting orders as well as takers) or apply a reduced multiplier to certain families. A flat per-contract fee, by contrast, costs the same at 5¢ as at 50¢; neither priced venue uses one.
What a $100 trade actually costs
| Polymarket (international book), $100 taker order | at 50¢ | at 80¢ | at 95¢ |
|---|---|---|---|
| Politics (rate 0.04) | $2.00 | $0.80 | $0.20 |
| Crypto (rate 0.07) | $3.50 | $1.40 | $0.35 |
Worked from the published formula of Polymarket's international book: $100 at 50¢ buys 200 shares, and 200 × 0.04 × 0.5 × 0.5 = $2.00. The same $100 at 95¢ costs $0.20, because the price term collapses near settlement. A maker order, one that rests on the book, pays nothing on Polymarket. Polymarket US, the exchange Americans trade on, charges 0.0695 on most markets: $3.48 on the same $100 at 50¢.
Kalshi's published fee schedule charges takers 0.07 × contracts × p × (1 − p) on most contract families, so the same $100 at 50¢ costs $3.50 and at 95¢ $0.35. A few families use half that rate or none, and some charge resting (maker) orders too.
Your own stake and price, with each venue's rounding: Payout calculator
The coin-flip case
At 50¢ the term price × (1 − price) is at its maximum of 0.25, so a quadratic fee is at its peak: a genuine toss-up is the most expensive contract to trade per dollar. That is worth knowing because toss-ups are also where the cross-venue spread tends to be widest, the fee and the price difference pull in opposite directions.
A $10,000 position
A quadratic fee scales linearly with size, so $10,000 in a Polymarket politics market at 50¢ pays $200.00, 100× the $100 figure. Slippage does not scale linearly: a large order moves the book, and that cost is not a fee and appears in no schedule.
Deposit and withdrawal costs
Funding rails per venue: Kalshi: ACH, RTP, debit card, Apple Pay, Google Pay, PayPal, Venmo, Cash App (deposits only), wire, crypto deposit; Polymarket: debit card, ACH, wire in the US; crypto, held as pUSD (Polygon) abroad; Robinhood: ACH, debit card, wire; FanDuel Predicts: debit card, Apple Pay, online banking. Polymarket charges no fee to deposit or withdraw on its international app, though on-ramps such as Coinbase or MoonPay may charge their own. Rail costs elsewhere (wire fees, card fees) are set by the venue or your bank and are not measured here.
What the table does not capture
- Spread. Buying at the ask and selling at the bid costs the gap between them, on every venue, with no fee line for it.
- Slippage on thin books; Kalshi's liquidity field is deprecated and unpublished, so book depth cannot be compared.
- Settlement differences. Two venues can word the same question differently and pay out differently; no fee schedule captures that.
- Funding costs on the rail you use.
Polymarket rates from Polymarket docs: Fees, read Sep 27, 2026; Kalshi models from its live series API. Venues change fees; their own pages are authoritative.
Common questions
Which prediction market has the lowest fees?
It depends on the price and the market. Both priced venues charge a quadratic fee that is highest at 50¢ and near zero close to settlement, and on Polymarket makers pay nothing and geopolitics markets are fee-free. Kalshi charges takers 0.07 on most of its markets against Polymarket's 0 to 0.07 by category, so which is cheaper depends on the category.
How is the Polymarket fee calculated?
As shares × rate × p × (1 − p), where the rate depends on the market's category (from 0 for geopolitics to 0.07 for crypto). Only the taker pays.
Is a quadratic fee worse than a flat one?
It depends where you trade. Near 0¢ or 99¢ a quadratic fee is tiny and a flat fee is not; at 50¢ the quadratic fee is at its peak. Neither is uniformly cheaper.