What this calculator does not do
- It does not tell you whether to offer the discount. That depends on what the cash is worth to you this month, which is not arithmetic.
- It uses a 365-day year and does not compound. It is a comparison figure, near enough to hold terms against each other, not a quoted rate.
- It does not know whether the discount changes the tax on the invoice. In some places a discount taken changes the taxable amount and needs a credit note; check how that works where you invoice.
- It does not keep anything. Nothing is written to your browser's storage while you use it and nothing is sent to us, so the figures are gone when you close the tab.
Related
To work the Net date out from terms more complicated than a day count — end of month, working days — use the invoice due date calculator. For what the invoice is worth once that date has gone past, there is the late payment fee calculator.
Last updated 21 September 2026