Invoice Due Date Calculator
Enter the date you issued an invoice and the payment terms, and this free calculator tells you the exact due date. No sign-up, no math, no second-guessing when a client's payment is late.
Payment due
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How to use this calculator
Start with the issue date: the day you sent the invoice to your client. Pick that date in the calculator.
Then choose your payment terms. Net 15, Net 30, and Net 60 are the most common, but you can set any number of days that matches your agreement. The tool counts forward from the issue date and shows the due date instantly.
If your client pays late, the due date is also your starting line for reminders. Note it on the invoice, add it to your calendar, and you will know the moment a payment slips past the deadline.
- Pick the issue date (the day the invoice goes out).
- Choose your terms, like Net 15 or Net 30, or enter a custom number of days.
- Read off the due date and copy it onto your invoice.
- Use that date to schedule follow-ups if payment runs late.
What payment terms and due dates actually mean
Payment terms set how long a client has to pay after you send an invoice. "Net" means the net amount is due in full, and the number is the count of days. So Net 30 means the full balance is due 30 days after the issue date.
The formula is simple: due date = issue date + the number of days in your terms. If you issue an invoice on June 9 with Net 30 terms, payment is due on July 9. Net 15 from the same date would be due June 24.
Most businesses count calendar days, not business days, so weekends and holidays are included in the count. The terms you choose are a balance between getting paid quickly and giving clients a reasonable window. Shorter terms like Net 7 or Net 15 speed up cash flow; longer terms like Net 60 are common with larger companies but tie up your money longer. Whatever you pick, agree on it up front and print the exact due date on every invoice so there is no ambiguity later.
Tip: make the due date impossible to miss
A vague "payment due upon receipt" invites slow payment. A specific calendar date does not. Always show the full due date on the invoice itself, near the total, not just the terms.
State the terms and the date together, for example "Net 30 — due July 9, 2026." Clients who would happily ignore "Net 30" tend to act on a real date. The same date should drive your own bookkeeping: it tells you when to expect the cash and when to start chasing it.
In Platybooks, new invoices default their due date from your saved payment terms, so the date is filled in for you and printed on the PDF automatically. You set the terms once and every invoice inherits them.
Tip: turn the due date into automatic follow-ups
The due date is only useful if something happens when it passes. Most late payments are not refusals; they are simply forgotten. A polite, on-time nudge fixes the majority of them.
A reliable cadence is a reminder at three days overdue, again at seven, and again at fourteen. Sending those by hand is easy to let slide, especially when you are busy with the work that earns the money.
Platybooks can send those overdue reminders for you on a +3 / +7 / +14 day schedule, follow up on unanswered quotes, and mark an invoice paid the moment a client pays through a hosted payment link. You calculate the due date once; the reminders and status updates run themselves.
Frequently asked questions
Does Net 30 mean 30 calendar days or 30 business days?
Net 30 almost always means 30 calendar days from the invoice issue date, including weekends and holidays. So an invoice issued on June 9 with Net 30 terms is due July 9. If you want to count only business days, say so explicitly on the invoice, because clients will assume calendar days by default.
What is the difference between Net 15, Net 30, and Net 60?
They are all the same kind of term with a different window. Net 15 gives the client 15 days to pay, Net 30 gives 30 days, and Net 60 gives 60 days, each counted from the issue date. Shorter terms get you paid faster and help cash flow; longer terms are common with larger clients but mean you wait longer for your money.
Should the issue date or the delivery date start the clock?
It depends on your agreement, but the issue date on the invoice is the most common and clearest starting point, which is what this calculator uses. Some contracts count from the delivery date or the date the client receives the invoice. Whichever you use, state it on the invoice so the due date is never in dispute.
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