/fees
What each platform actually charges
Sportsbooks state no fee. Prediction markets publish one, or they do not. Neither number tells you the whole cost, so this page computes it the same way for all 13, from the two-sided prices each platform quotes on the same market and from the fee method each one has published.
Cost on a $100.00 stake, in dollars, if you win.
| Platform | Where the cost sits | In the price | Published fee | Total on your stake |
|---|---|---|---|---|
| PolymarketPrediction market | Charged at settlement, from winnings | 1.96% | 2% of winnings | $3.73 |
| FanDuelSportsbook + prediction | Built into the quoted price | 4.50% | None stated | $4.50 |
| FanaticsSportsbook | Built into the quoted price | 4.50% | None stated | $4.50 |
| RebetSportsbook | Built into the quoted price | 4.51% | None stated | $4.51 |
| BetMGMSportsbook | Built into the quoted price | 4.54% | None stated | $4.54 |
| CaesarsSportsbook | Built into the quoted price | 4.54% | None stated | $4.54 |
| UnderdogDFS / Sweeps | Built into the quoted price | 4.54% | None stated | $4.54 |
| OnyxDFS / Sweeps | Built into the quoted price | 4.54% | None stated | $4.54 |
| DraftKingsSportsbook + prediction | Built into the quoted price | 4.55% | None stated | $4.55 |
| SleeperDFS / Sweeps | Built into the quoted price | 4.55% | None stated | $4.55 |
| KalshiPrediction market | Charged on the trade, on top of the price | 0.99% | Trading fee, 0.07 × contracts × price × (1 − price) | $8.02 |
| ProphetXPrediction marketFee not published | Not published | 0.99% | Not published | Margin only. Fee not stated. |
| OG MarketsPrediction marketFee not published | Not published | 1.96% | Not published | Margin only. Fee not stated. |
A sportsbook states no fee. That does not mean it is free: its margin is inside the number it quotes, and the arithmetic above recovers it. Add the implied probability of both sides of the same market, and the amount by which the total exceeds 100% is the platform's cut. An exchange quotes a much tighter two-sided spread and then charges an explicit fee, so its cost is split across two places rather than hidden in one. Neither figure is a recommendation, and a lower cost on this page does not mean a better price on your selection. That depends on the line, which is what the comparison table is for.