With Predictions powered by Polymarket now live in the Betr app, it's worth knowing exactly when and how a fee applies before you place a trade.
A small taker fee kicks in on select markets. You never have to think about it when placing an order, the protocol handles the calculation automatically at the moment a trade matches. Neither Betr nor Polymarket profits from these fees. They're simply charged as part of how the market functions, not as a revenue source.
A few things stay completely free no matter what: geopolitical and world events markets carry zero fees, and depositing or withdrawing USDC never costs anything on Betr's end.
How the fee is calculated
The formula behind every fee looks like this:
fee = C × feeRate × p × (1 - p)
C is the number of shares in the trade, and p is the price of those shares.
Only takers ever pay. Makers are exempt across the board. What changes from market to market is the rate itself:
Category | Taker Fee Rate | Maker Fee Rate |
Crypto | 0.07 | 0 |
Sports | 0.05 | 0 |
Finance | 0.04 | 0 |
Politics | 0.04 | 0 |
Economics | 0.05 | 0 |
Culture | 0.05 | 0 |
Weather | 0.05 | 0 |
Other / General | 0.05 | 0 |
Mentions | 0.04 | 0 |
Tech | 0.04 | 0 |
Geopolitics | 0 | 0 |
Because the fee is denominated in USDC and scales with price, it lands the same at mirrored probabilities. A trade at 30¢ costs exactly as much as one at 70¢.
How small can a fee get?
Every fee gets rounded to five decimal places, with 0.00001 USDC as the floor. Once a calculated fee dips below that, it simply rounds down to zero, which means very small trades near the edges of the probability range can end up costing nothing at all.