Free document tools
Invoice Due Date Calculator
Enter an invoice issue date and the payment term in calendar days to find its due date. The calculation handles month lengths and leap years and shows exactly how days are counted.
Calculate a due date
Count calendar days starting the day after the issue date. Net 0 uses the issue date. Weekends and public holidays are included.
Inputs are not saved unless you choose to remember them.
Enter an issue date and payment term to see the due date.
How to use this calculator
- Enter the invoice issue date using the date field.
- Enter the agreed number of calendar days: for Net 30, use 30. Use 0 when the payment is due on the issue date.
- Select Calculate due date and compare the result with the terms on the invoice or agreement.
How the date is calculated
- The issue date is day zero. Counting starts on the following day, so 11 September 2026 plus 30 days is 11 October 2026.
- Weekends and public holidays are included. Terms based on business days or the end of a month need a different calculation.
- The result is a calendar calculation. It does not establish a statutory payment deadline, assess late fees or send a payment reminder.
Common questions
What does Net 30 mean in this calculator?
Net 30 adds 30 calendar days to the issue date. For an invoice dated 11 September 2026, the result is 11 October 2026. Check whether your agreement uses that same convention.
Are weekends and holidays excluded?
No. Every calendar day is counted. The tool does not move a due date that falls on a weekend or public holiday.
Can I calculate Net 15, Net 60 or Net 90?
Yes. Enter 15, 60 or 90 in the payment-term field. Any whole number from 0 to 365 is supported.
Does it save my dates?
Only if you select Remember inputs in this browser. Clear inputs removes the saved calculator draft. The calculator does not need an account and does not submit your dates to a server.