What a Prediction Market Trade Actually Costs
Prediction market fees are not a flat commission, and that is the part most people get wrong. On almost every regulated venue, what you pay depends on the price of the contract you are buying — and it peaks precisely where sports markets tend to sit.
The pricing is public. It is written as a formula rather than a number, which is why so few readers ever work out what they are actually paying.
Why almost every venue charges most at 50/50
The standard structure is a coefficient multiplied by price × (1 − price). That expression is largest when a contract trades at 50 cents and falls away towards either end of the range.
The logic is that fees scale with genuine uncertainty. A contract at 97 cents is nearly settled and costs almost nothing to trade. A coin flip costs the most.
Two consequences follow, pointing in opposite directions:
- Sports contracts sit near the peak. A close game prices near 50 cents, the single most expensive point on the curve.
- Longshots and heavy favourites are cheap. The venue charging $1.75 per 100 contracts at 50 cents charges 63 cents at 90 cents.
What 100 contracts cost on each platform
Two words you will meet on every platform. You are a taker if you buy at the price already showing. You are a maker if you post your own price and wait for someone to trade against it.
Figures below are for 100 contracts at 50 cents — a $50 position, and the most expensive point on the curve. We use 100 rather than a single contract because most venues round to the nearest cent, which distorts single-contract comparisons badly. Kalshi, Polymarket US and Robinhood all publish their own tables on the same basis.
| Venue | Taker (per 100) | Maker | Cost on $50 |
|---|---|---|---|
| Polymarket global (politics) | $1.00 | Free | 2.0% |
| ForecastEx via Interactive Brokers | $1.00 | $1.00 | 2.0% |
| Polymarket global (sports) | $1.25 | Free | 2.5% |
| Polymarket US | $1.50 | $0.31 rebate | 3.0% |
| Kalshi | $1.75 | Free on most | 3.5% |
| Robinhood | $1.00 + $1.00 | Same as taker | 4.0% |
| FanDuel Predicts | $2.00 | Same as taker | 4.0% |
| Crypto.com | Not published | Free | — |
Robinhood's taker figure is $1.00 commission plus a $1.00 exchange fee. Where a venue shows "same as taker" it charges per contract regardless of who initiated the trade — the maker rebate is an exchange feature, not a universal one. ForecastEx charges the same $1.00 to both sides.
Derived from each platform's own published schedule: Kalshi's fee schedule PDF (effective 7 July 2026), docs.polymarket.us (effective 1 July 2026), docs.polymarket.com, Robinhood Derivatives' fee schedule and event contracts help pages (effective 1 June 2026), ForecastEx's CFTC-filed schedule, and Crypto.com's help centre.
Three things there are worth pulling out.
Polymarket US pays makers. Resting an order that someone else fills earns 31 cents per 100 contracts rather than costing anything, and taker volume above $250,000 a month earns rebates from 10% up to 50% past $10m. Kalshi's July schedule sets its maker multiplier to zero by default, so on most Kalshi markets making is free too — though a named list of roughly 85 series, including every major US league game market and the main economic releases, does carry a maker fee.
Polymarket's international exchange prices by category — 7% on crypto, 5% on sports, 4% on politics, and nothing at all on geopolitical markets. It also charges no withdrawal fee. But it is a separate venue from Polymarket US, on different legal footing, and checking one tells you nothing about the other.
Robinhood's exchange fee is charged per side. The one cent applies on the way in and again on the way out, so a round trip costs $2.00 per 100 contracts in exchange fees alone.
The Robinhood Gold trap
Robinhood moved to a probability-weighted commission on 1 June — 10% of price × (1 − price), halved to 5% with Gold. That reads like Gold saves you half.
It does not, because the same schedule caps commission at one cent per contract. At 50 cents, the uncapped Gold rate would be $1.25 per 100 and the non-Gold rate $2.50. Both get cut to $1.00.
Between roughly 28 cents and 72 cents, Gold and non-Gold cost exactly the same. Gold only starts paying off outside that band — at 90 cents it is 45 cents per 100 against 90 cents without. If you mostly trade close games, Gold buys you nothing on fees.
Where FanDuel breaks from everyone else
FanDuel Predicts charges 2% of your potential payout, taken at checkout, and the same 2% applies if you cash out early.
That is a different animal. It is not scaled to uncertainty, so it does not fall away at the ends of the range — it stays at $2.00 per 100 contracts whether the contract is a coin flip or a near-certainty.
At 50 cents, FanDuel's $2.00 sits just above Kalshi's $1.75. At 90 cents, Kalshi charges 63 cents and FanDuel still charges $2.00. On heavy favourites FanDuel costs roughly three times what the formula-based venues charge.
If you mostly back favourites, that single structural difference outweighs every other fee consideration here.
Which venues won't tell you the price
Four are opaque. DraftKings DKeX publishes a rulebook saying fees will be "reflected on the Website," with no figure attached. Coinbase discloses fees only on the order confirmation screen. ProphetX markets itself as free to play with no schedule. Novig describes itself as commission-free without detail.
Crypto.com is a worse case, because it publishes three different answers. Its help-centre table gives a taker range of $0.01 to $0.0175 per contract; the worked examples on that same page apply a flat $0.0175 regardless of price; and its learn page states a flat $0.02. We cannot give you a reliable figure for Crypto.com, and neither can they.
Where a venue will not publish a rate, read the confirmation screen before you commit — and treat the absence as information.
The honest read
Fee differences here are real but small in absolute terms. Across the whole table, the same $50 position costs between 2% and 4% of your money. Trade rarely and it barely registers.
What changes the maths is price range and order type. If you mostly back favourites, FanDuel's flat 2% of payout will cost you multiples of everyone else. If you rest orders rather than crossing the spread, Polymarket US pays you where most venues charge nothing — and that swing is larger than the entire spread between venues on the taker side.
None of it matters if the market you want has no depth. A cheap fee on a venue where nobody is trading the other side of your contract is not a saving. Check liquidity first, then fees, then whether you can legally trade there at all.
Venue-by-venue registration status sits on our prediction market platforms page.