Overdraft Fee Calculator

About this calculator

An overdraft fee is a flat charge a bank applies when a customer’s checking account balance goes negative because a debit, check, or withdrawal exceeds the available funds, and the bank covers the shortfall rather than declining the transaction. Banks typically charge a fixed dollar amount per overdraft event, and some also apply a separate extended or “sustained” overdraft fee if the account remains negative for several consecutive days.

A related but distinct charge, the non-sufficient funds (NSF) fee, applies when the bank declines the transaction outright instead of covering it, still leaving the customer with a fee but no completed payment. Because these fees can compound quickly if multiple transactions post while an account is negative, this calculator estimates the total cost of overdraft activity — number of overdraft events multiplied by the per-event fee, plus any extended fees — helping account holders see the real cost of an overdrawn balance.