Due date calculator
Calculate a due date from a start date and payment term for simple invoice and payment planning.
Calculate due date
The weekend adjustment only checks Saturday and Sunday. It does not account for bank holidays, public holidays or other local exceptions.
What the due date calculator shows
The due date calculator shows when a payment becomes due when you know the invoice date and the payment term in days. The result shows the invoice date, the payment term, the due date before any weekend adjustment and the final due date.
How to use the calculator
Enter the invoice date, choose a payment term or enter a custom number of days, then press Calculate. You can optionally move a Saturday or Sunday due date to the next weekday.
How the due date is calculated
The calculator adds the payment term in days to the invoice date. If the invoice date is 1 January 2026 and the payment term is 14 days, the due date before weekend adjustment is 15 January 2026. A zero-day payment term means the same date as the invoice date.
Example calculation
- Invoice date 1 January 2026 and payment term 14 days -> due date 15 January 2026.
- Invoice date 1 January 2026 and payment term 30 days -> due date 31 January 2026.
- If weekend adjustment is enabled, 31 January 2026 falls on a Saturday and the final due date moves to Monday 2 February 2026.
Payment terms and calendar days
The payment term is treated as calendar days: the 7, 14, 21 and 30 day presets, and any custom payment term, are added to the invoice date as a date calculation. The calculator does not read the payment term from an invoice or contract; it uses the number of days you enter.
Weekends, holidays and local rules
Weekend adjustment only checks Saturday and Sunday: a due date that lands on either day is moved to the following Monday. The calculator does not automatically account for public holidays, bank holidays, country-specific rules, contract-specific exceptions or legal deadlines.
Limitations
The calculator is a practical date tool. It does not replace legal advice, official guidance, local deadline rules or contract interpretation. Check binding due date rules separately when the date has legal or financial consequences.
Frequently asked questions
Is the due date calculated from the invoice date?
Yes. The calculator adds the payment term days to the invoice date. For example, 1 January 2026 plus 14 days is 15 January 2026.
Can I enter a custom payment term?
Yes. Choose the custom payment term option and enter the number of days as a whole number.
Does the calculator account for public holidays or bank holidays?
No. The weekend adjustment only checks Saturday and Sunday. Public holidays, bank holidays and other local exceptions must be checked separately when they matter.
Can the payment term be zero days?
Yes. A zero-day payment term means the due date is the same day as the invoice date.
What if an agreement uses a different due date rule?
Follow the agreement or the rule that applies to your situation. This calculator gives a general date calculation result.