Invoice payment tools
Invoice Due Date Calculator
Turn an agreed number of calendar days into a clear payment date. Compare Net 7, 14, 30 and 60 from the same start date, then copy the result into your invoice.
By InvoiceGen · Updated
Calendar-day calculation
When is this invoice due?
Starts with an example date. Enter the start date specified in your agreement, whether that is the invoice date or the receipt date.
Calculated due date
November 12, 2026
2026-11-12 · Thursday. The start date is day 0.
Calendar days include weekends and holidays. No automatic holiday, business-day or end-of-month adjustment.
Compare dates from the same start
- Net 7
- October 20, 2026
- Net 14
- October 27, 2026
- Net 30
- November 12, 2026
- Net 60
- December 12, 2026
How this date calculation works
The formula is start date + the number of calendar days. The start date is day 0, so one day after October 13 is October 14. Every date counts, including weekends and holidays. The calculation uses the date alone, so a change of time zone or daylight saving time does not remove a day.
The start event matters. Payment terms can be tied to the invoice date, receipt of goods, or another agreed event. Stripe describes these different arrangements in its guide to 30-day payment terms. Choose the start date that matches your agreement.
This calculator implements calendar-day addition only. It does not interpret a contract, calculate statutory deadlines, count business days, or apply end-of-month terms. A weekend flag leaves the result unchanged; check the agreed payment date before putting it on the invoice.
Worked examples across months and years
October 13, 2026 + 30 calendar days
November 12, 2026
18 days to October 31, then 12 more days.
January 31, 2027 + 30 calendar days
March 2, 2027
February has 28 days; adding 30 days is different from adding one month.
February 28, 2028 + 1 calendar day
February 29, 2028
The calculation includes leap day.
December 20, 2026 + 14 calendar days
January 3, 2027
The result crosses a year boundary and remains Sunday.
Put the date into a finished invoice
- Check the agreed start event and payment interval with the client.
- Copy the calculated date. In the invoice generator, enter it in the Due Date field.
- Copy the payment wording into Notes, replacing any old wording that conflicts with the date.
- Preview the invoice and check that its date, payment instructions and email agree.
For the example shown above, October 13, 2026 + 30 days produces November 12, 2026. The tool does not change an invoice you already have open.
Due date questions
Is Net 30 the same as adding one month?
This calculator adds 30 days, not one calendar month. Months have different lengths. From January 31, 2027, 30 days leads to March 2, 2027.
What happens if the result is a Saturday or Sunday?
The tool displays the weekend date and a note. It does not move the date to Monday. Any adjustment must match the terms that apply to your invoice.
Does “Same day” mean due on receipt?
Same day adds zero days to your chosen start date. If the agreement says due on receipt, use the relevant receipt date; the tool cannot detect when a client received an invoice.
Can I calculate 30 days after the end of a month?
There is no automatic end-of-month mode. If your agreement explicitly starts the interval at month-end, enter that month-end date as the start, then add 30 days. Do not substitute the invoice date.