Fees are charged on notional, not margin
This is the trap: at 20x a 0.055% fee feels tiny but it's 1.1% of your margin every round trip. Scalp often and it dwarfs your edge. See the full drain on the fee drag calculator and break-even.
Fees at leverage: the multiplication people skip
Exchange fee schedules quote percentages of notional — 0.055% taker on most major venues. Innocent enough on spot. At leverage, the same percentage applies to your multiplied position, so as a share of the money you actually put up, fees scale linearly with leverage: 0.055% taker at 20x is 1.1% of margin per side, 2.2% round trip.
Concrete: $500 margin, 20x, in-and-out with market orders = $22 in fees. Your position must move 0.11% in your favor just to cover the toll. Scalpers doing ten round trips a day at this size pay $220 daily — $6,600 a month against a $500 stake. This is why fee-unaware scalping systems always die, and why maker rebates and fee tiers aren't small print but the entire margin of survival.
The fix hierarchy: use limit orders (maker fees run 0.02% or lower, sometimes negative), trade fewer, larger setups instead of many small ones, and check your 30-day fee total against your 30-day PnL monthly. Most losing months are fee-shaped.