Late Fee Calculator
Work out exactly what an overdue invoice is costing — interest accrued, per-day rate, and the total now due. Free, instant, no signup.
Overdue invoice
Late fee terms
UK businesses can also claim fixed compensation per overdue invoice (£40–£100 depending on the debt). Interest is simple, not compound, calculated per day.
Total now due
$1,006.58
How to use it
- Enter the overdue invoice amount and how many days overdue it is.
- Set the annual late-fee rate — use a preset or type your contract rate.
- Add an optional flat fee (like the UK's £40–£100 statutory compensation).
- See the interest accrued, the per-day rate, and the total now due.
Frequently asked questions
How is late fee interest calculated?
Multiply the overdue amount by the annual rate, then by days overdue divided by 365. For example, $1,000 at 8% for 30 days accrues $6.58 in interest.
What late fee rate should I charge?
It depends on your contract and your country. In the UK, statutory interest for business debts is the Bank of England base rate plus 8% per year. Elsewhere, use the rate agreed in your contract — keep it reasonable.
Is my data stored anywhere?
No. All calculations happen instantly in your browser. Nothing is entered, stored, or sent anywhere.