The ‘fee floor’ evolves alongside network usage. If the mempool is persistently full, miners naturally pick transactions with higher fees, pushing out extremely low-fee transactions. Over time, this behavior establishes a practical threshold—often in the range of a few sat/vByte—below which it’s improbable your transaction will confirm in a timely manner.

This floor isn’t a hard rule; if the network quiets down, even very low-fee transactions might confirm eventually. But under steady demand, transactions paying a fraction of the dominant rate end up stuck. Recognizing this dynamic helps users set realistic fees to avoid indefinite delays.