Quick answers beat spreadsheets for one-off invoicing questions. This section collects small, free calculators for the parts of invoicing that are easy to get wrong when you do them by hand, starting with due dates.
Every tool here works without an account or a sign-up: enter your numbers, read the answer, and move on. None of them store what you type, and none of them send anything anywhere on your behalf.
The net 30 calculator works out an invoice's exact due date from the invoice date and a term of your choosing, including net 15, net 45, net 60, or a custom number of days. It also flags when a due date falls on a weekend, and shows the date an invoice becomes officially overdue. If you'd rather read about what a term like net 30 actually means before you use it, see the payment terms guide.
More small tools are planned for this section over time, covering other places where a quick, correct calculation saves you from doing the arithmetic yourself.
- Net 30 calculator
Free net 30 calculator: enter the invoice date to get the due date, the days remaining, and the day it becomes overdue. Also works for net 15 and net 60.