Free · No sign-up · 100% offline

Free invoice late fee calculator

A client is past due. Enter the invoice and your late-fee terms — flat fee, percentage per month or annual interest — and get the fee, the total now owed, and a polite reminder you can copy and send. Runs in your browser, nothing uploaded.

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Charge for late payment without the awkward math

Late payment is one of the most common freelance headaches, and a late fee — agreed up front in your contract — is the polite, professional way to discourage it. The hard part is usually the arithmetic and the wording: how many days overdue is it, what does that work out to, and how do you ask for it without sounding aggressive? This calculator does both.

Enter the invoice amount and due date, choose how your contract charges late fees, and the tool shows the days overdue (after any grace period), the late fee, and the total now due. It also drafts a short, courteous reminder message with those numbers filled in, ready to copy into an email.

What it works out

Days overdue

Counts from the due date to today (or a date you pick), minus your grace period.

Three fee methods

Flat fee, percentage per month, or an annual interest rate applied over the days overdue.

Total now due

Invoice amount plus the late fee, in your currency.

Copy-ready reminder

A polite, professional message with the amount, days overdue and total — one click to copy.

Grace period

Set a few days of grace so a fee only applies once it is genuinely overdue.

Private & offline

Runs entirely in your browser. The invoice details never leave your computer.

How to calculate a late fee in 3 steps

  1. Enter the invoice amount and due date (and today, or the date you are charging from).
  2. Pick your fee method — flat, percentage per month, or annual interest — and any grace period.
  3. Read the total and copy the reminder to send your client.

A note on what you can charge

Late fees work best when they are written into the contract you agreed before starting — which is exactly what ProposalPro helps you set up. Many places also regulate or cap late fees and interest, so treat this as an estimate, not legal advice, and confirm what is enforceable where you are. Once you know the figure, you can reissue the bill with InvoicePro.

Frequently asked questions

Is this late fee calculator free?
Yes, completely. It runs in your browser with no account and nothing uploaded.
How much late fee can a freelancer charge?
Commonly a flat fee, a percentage per month (often 1–2%), or an annual interest rate. What you can actually charge depends on your contract and local law — set the terms in your agreement and confirm what is allowed.
How are days overdue calculated?
From the due date to today (or a date you choose), minus any grace period. If it is not past due yet, the fee is zero.
Can I send the client a reminder?
Yes — the tool generates a polite reminder with the amount, days overdue, fee and total, ready to copy.
Is this legal or financial advice?
No. It is an estimate to help you apply your own contract terms. Confirm what is enforceable with a professional.

More free tools for freelancers

Part of a set of offline, no-subscription tools for the whole freelance workflow:

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Work out the fee and send a polite nudge in two minutes. Free, no account, nothing uploaded.

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