For every executed order, there is a Trading Fee incurred.
Note that the actual order cost will be reserved for open taker (0.07%) transaction fee; however, the actual transaction fee will be paid when the order is executed and calculated based on the actual transaction price. When all orders are completed, if there is still remaining after deducting the actual fees for, it will be automatically returned to the available assets.
The formula for USDT Perpetual Contract:
Trading Fee = Contract Face Value * Trading Fee Rate * Filled Price
Order value = Contract Face Value * Contract Size * Filled Price
Trader A buys 100 BTCUSD contracts using Market order. （1 contract face value=0.001BTC）
Assuming that the execution price is 18,000 USD:
Taker fee for Trader A = 0.001*100*18000*0.07% = 1.26USDT