Free Calculator

Late Fee Calculator

Calculate the exact late fee or interest charge on an overdue invoice. Supports both simple and compound interest methods.

Calculate your late fee

Interest Type

Interest accrues only on the original principal for each day overdue.

Late fee$9.86
Total amount due$1,009.86

Formula: Principal × Rate × Days ÷ 365

How Late Fee Calculation Works

Three steps to estimate what you can charge on overdue invoices.

1

Enter invoice details

Input the original invoice amount, the annual interest rate you charge, and how many days the payment is overdue.

2

Choose interest type

Select simple interest for a straightforward calculation, or compound interest if your terms specify monthly compounding.

3

Get your results

See the late fee and total due instantly. Use these figures when following up with your client.

Frequently Asked Questions

Common questions about late fees and interest charges on invoices.

Automate Late Fee Tracking

Stop calculating late fees manually. Invoice My Clients automatically tracks overdue invoices and calculates interest charges for you.

Related resources

Learn more about interest on invoices and overdue payment workflows.