Free tool
Invoice due date calculator
Use this free invoice due date calculator to turn an issue date and a payment term like Net 15, Net 30 or Net 60 into an exact due date, leap years included.
Updated · By PayToMe Editorial
Result
Calculated in your browser. Nothing is sent anywhere.
Read the full guide: how to use it, what to include, worked example
An invoice due date calculator turns two things, the day you issue an invoice and the payment term you agreed, into one exact due date. Pick the issue date above, choose Net 15, Net 30, Net 60 or enter your own number of days, and the result updates live. Everything runs in your browser, and nothing you enter is uploaded.
How to use the calculator
- Enter the issue date. This is the date printed on the invoice, not the date the work started.
- Choose the term. Net 7, 15, 30, 45 and 60 are common. You can also type a custom number of days.
- Read the due date. It appears as a full calendar date, with the day of the week.
- Copy it onto the invoice. Writing the actual date, not only “Net 30”, removes any doubt.
If a client pays late, the late fee calculator picks up from the due date you worked out here.
How the math works
A net term is a count of calendar days. “Net 30” means payment is due 30 days after the invoice date. To find the due date, start from the issue date, do not count that day, and count forward one day at a time. Months have different lengths, so the calculator uses the real calendar, including February and leap years, instead of assuming 30-day months.
In plain words: the due date is the issue date plus the number of days in the term. If the count runs past the end of a month, it carries into the next month, and past December into the next year.
Worked examples
| Issue date | Term | Due date |
|---|---|---|
| 2026-01-31 | Net 30 | 2026-03-02 |
| 2026-12-20 | Net 15 | 2027-01-04 |
| 2028-01-01 | Net 60 | 2028-03-01 |
Choosing a payment term
Shorter terms bring cash in sooner. Longer terms are easier for large clients with slow approval processes. A few guidelines:
- Due on receipt or Net 7 suits small jobs, one-off projects and new clients.
- Net 15 is a common middle ground for freelancers and trades.
- Net 30 is the most common term in business-to-business work. See the glossary entry for Net 30.
- Net 60 is often set by a large client’s accounts payable policy. Read about Net 60 before agreeing to it, since it stretches your cash flow.
Our guide to invoice payment terms covers deposits, early payment discounts and how to word the terms on the invoice.
Common mistakes
- Counting the issue date as day one. Day one is the next day. Counting it makes your due date one day early.
- Assuming every month has 30 days. January 31 plus 30 days is March 2, not February 30 or March 1.
- Mixing calendar and business days. Net terms are calendar days unless the contract says otherwise.
- Backdating the invoice. The due date follows the issue date. If you send the invoice a week after you dated it, the client effectively loses a week.
- Writing only “Net 30”. Print the date as well. It prevents arguments and helps the client’s payment run.
- Forgetting that “end of month” terms are different. Terms like “Net 30 EOM” start the count from the end of the issue month. This calculator uses plain net days.
What to put on the invoice
A clear invoice shows the issue date, the term and the actual due date, such as “Issued 2026-01-31, Net 30, due 2026-03-02”. Add the accepted payment methods and any late fee rule. When these details are explicit, there is less back and forth and fewer overdue reminders to send.