Pricing & invoicing
Invoice Late Fee Calculator
Enter the invoice, the due date and your late-fee terms. See the total owed today and copy a ready-to-send reminder.
Frequently asked questions
Am I allowed to charge a late fee?
That depends on your contract and the law where you and your client operate, so check what applies to you. Whatever terms you use, the calculator works out what is owed from the fee type, rate and dates you enter.
Flat fee, one-time percentage, or monthly percentage — which should I use?
A monthly percentage keeps growing as the invoice ages. A one-time percentage is simpler but stops growing. A flat fee is the same amount whatever the invoice size. Use whichever your terms state, and apply it consistently.
What is the grace period for?
A grace period is a number of days after the due date before any fee applies. Set it to match your terms, and the calculator only starts the clock once the grace window has passed.
What is the "copy reminder line" for?
It drafts a polite but firm chase message with the exact amounts filled in, so you can paste it straight into an email. Staying matter-of-fact and specific gets invoices paid faster than apologising for asking.
These calculators give estimates to help you think — not financial, tax or legal advice. Double-check anything that matters with a professional.