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Invoice due date calculator

An invoice's due date is the invoice date plus the days in the payment terms. Pick the invoice date and net 7, 15, 30, 45 or 60 terms, or your own number of days, to see the due date. Add the date it was paid to see days late and an optional late fee. It runs in your browser.

Your files

The date on the invoice.

Net 30 means due 30 days after the invoice date.

Late fee (optional)

Fill these in to see days late and the fee up to the date it was paid. Use only what your contract says.

Needed for a percent fee, and for the total.

Charged once if the payment is late.

Charged for each 30 days late, by the day.

Results

Choose the invoice date to see the due date.

Editable spreadsheet

Pro gives you this calculation as an Excel file with live formulas, so you can change a number and watch every result update. It opens in Excel and Google Sheets.

Get Pro for the Excel file

These figures are estimates for planning. They are not financial, tax or investment advice. Your contract and local rules decide whether a late fee can be charged and how much. Rules vary, so check yours. Working out a result is free and never counted. Saving the PDF counts as one of your free uses; Pro has no limit.

The formulas in words

  • Due date = the invoice date plus the days in the payment terms.
  • Days late = the pay date minus the due date, or 0 if it is not later.
  • Percent fee = invoice amount times the percent per month times the days late, divided by 30.
  • Late fee = the flat fee if the payment is late, plus the percent fee.
  • Invoice amount plus late fee = the invoice amount plus the late fee.

How do I calculate an invoice due date?

Add the number of days in the payment terms to the invoice date. Net 30 on an invoice dated November 1, 2026 is due on December 1, 2026, because November has 30 days. Pick the invoice date and the terms above and the calculator counts across month ends and leap years for you.

What does net 30 mean?

Net 30 means the full invoice amount is due 30 days after the invoice date. Net 15 and net 60 work the same way with 15 or 60 days. Some invoices count from the day the goods or the invoice arrive instead, so check the terms you agreed in writing.

How is a late fee worked out here?

Enter the date paid, the invoice amount and your fee. Days late is the pay date minus the due date. A flat fee is charged once when payment is late. A percent per month is charged for each 30 days late, by the day. For example, $2,000 at 1.5% for 30 days is $30.

Can I charge a late fee on an invoice?

Only if your contract or invoice terms say so, and rules vary by place, including limits on interest and fees. This calculator does not state any limit. Put the late fee terms in writing before the work starts, and check your local rules or ask a lawyer before you charge one.

Put the numbers on paper

Key facts

  • Privacy: We don't sell your data. This tool runs in your browser, so your files stay on your device and are never uploaded.
  • Ads: none. No third-party ads and no ad cookies.
  • Limits: working out a result is free, needs no account and is never counted. Saving the result as a PDF counts as one of your free uses. Emailing it to yourself is optional. Pro has no limit on uses with Pro.
  • Price: free to start. The editable Excel version with live formulas is part of Pro, $2.99 a month or $24 a year. Pro cancels in one click.
  • Results are estimates for planning, not financial, tax or investment advice.

Last updated:

By the PDFinish editorial team · Reviewed

Common questions

Is the invoice due date calculator free?

Yes. Working out a result is free, needs no account and is never counted. Saving the result as a PDF counts like any other PDFinish file under the free allowance shown on this page. The editable Excel version is part of Pro.

Are my numbers uploaded?

No. The maths runs in your browser and nothing you type is sent to our servers. If you choose Email it to me, only the finished PDF is sent, to the address you give, and we delete it after 7 days.

Does it skip weekends or holidays?

No. It counts calendar days. If the due date lands on a weekend, the page tells you. Whether payment is then due that day or the next business day depends on your terms and local rules, so check what you agreed.

What does the Excel download include?

Pro members can download a spreadsheet with the invoice date, terms and late fee settings in cells and live formulas for the due date, days late, the fee and the total. Change a number in Excel or Google Sheets and every result updates.

Is this legal or financial advice?

No. The results are estimates for planning. They are not legal, financial or tax advice, and they do not check whether a late fee is allowed where you live. Ask a qualified adviser about your own situation.