Invoice Due Date Calculator
Enter the date on the invoice and the payment terms. The calculator gives you the due date, the weekday, and how many days are left. Runs in your browser; nothing is sent anywhere.
How payment terms turn into a due date
Payment terms describe how long a client has to pay after the invoice date. "Net 30" means the full amount is due 30 days after the issue date. "Due on receipt" means the day the client receives the invoice, which in practice is the issue date. The maths is simple, but two details trip people up: whether you count calendar days or business days, and what happens when the due date falls on a weekend.
Almost every contract means calendar days unless it says otherwise. If your terms say "30 days", count every day including weekends and public holidays. Some larger clients, particularly in government and construction, write "30 business days" or "30 working days" into their terms, and that is a very different date: 30 business days is closer to six weeks. This calculator lets you switch between the two so you can see the difference before you send the invoice.
Why the issue date matters more than the send date
The clock starts from the date printed on the invoice, not the day you happen to email it. If you finish work on a Friday, write up the invoice on Monday and date it Monday, you have given the client three extra days. Date the invoice the day the work is complete or the day agreed in your contract, and send it the same day.
Invoicing late is one of the most common reasons for getting paid late: every day between finishing the work and sending the invoice is a day added to the wait. Use this tool the moment you write the invoice, put the due date on the invoice in words and numbers, and add it to your calendar.
Weekend and holiday due dates
When a due date lands on a Saturday, most clients will pay on the following Monday and nobody considers it late. Ticking the roll-forward option moves the due date to the next weekday so your records match what will really happen. Public holidays vary by country, so the calculator does not try to guess them; if a due date lands on a national holiday, move it by hand.
Choosing terms that get you paid
Shorter terms get paid faster, but only if the client's accounts team can process them. A typical pattern for freelancers and small studios is net 14 for small clients and net 30 for companies with a purchasing department. Anything longer than net 30 is a favour to the client and should come with a reason, such as a large retainer or a discount for early payment. If a client insists on net 60 or net 90, consider a deposit up front so you are not funding their cash flow.
Whatever you choose, state it in the contract, repeat it on the invoice, and use the same wording each time. "Payment due within 30 days of invoice date" is clear. "Payment due promptly" is not.
Frequently asked questions
Does net 30 include the invoice date?
No. Day one is the day after the invoice date. An invoice dated 1 March with net 30 terms is due on 31 March.
What is the difference between net 30 and 30 days end of month?
Net 30 counts from the invoice date. "30 days EOM" counts from the end of the month in which the invoice was issued, so an invoice dated 3 March on 30-days-EOM terms is due 30 April. This calculator handles net terms; for EOM terms, enter the last day of the month as the issue date.
Can I charge a late fee once the due date passes?
Only if your contract or terms say so. If they do, our late payment fee calculator works out the amount for any number of days late.
Is my data stored?
No. The calculation runs entirely in your browser.