Changelly charges a 0.25%* transaction fee on both types of interest rates: fixed and floating.
A floating exchange rate means that the rate is based on market value which can change at any moment. This means that from the time your transaction starts, the rate could change by the time your transaction is complete.
A fixed exchange rate means that the rate is guaranteed. Changelly offers users a fixed rate, but the transaction must be completed within 15 minutes to receive the offered rate.
*Rates current as of August 2021