Invoice Late Fee Calculator
Calculate a late fee on an overdue invoice based on days late and an annual interest rate.
Fill in the invoice amount and due date to calculate a late fee.
Check your contract or invoice terms for the actual late fee rate and structure — this calculates simple daily interest, but not every agreement uses that method.
Overview
Calculates a simple daily-interest late fee on an overdue invoice, based on the amount, days overdue, and your stated annual rate.
- Shows both the late fee and the new total owed
- Flags invoices that aren't actually overdue yet
- Instant results as you adjust any input
How to use it
- 1Enter the invoice amount and due date
- 2Enter your annual late fee rate
- 3Read the calculated late fee and new total
Frequently asked questions
What interest rate should I use?
Whatever your invoice or contract specifies as the late payment terms — this is commonly stated as an annual percentage, sometimes alongside a grace period before it starts accruing.
Does this account for a grace period?
No — it calculates from the due date directly. If your terms include a grace period, use a due date that already reflects it.