Late Fee Calculator
If your terms allow it, you can charge interest on invoices paid late. Enter the invoice, the rate and the days overdue to see what to add.
Enter your figures below. Results update as you type.
Total now due$5,110.96
- Interest owed
- $110.96
- Flat late fee
- $0.00
- Interest per day
- $2.47
- Interest per month
- $75.00
You can usually only charge late interest that was agreed in the contract or stated on the invoice, and states cap the rate. Simple interest is used here.
How the Invoice Late Fee calculation works
Interest = invoice x yearly rate x days overdue / 365
A $5,000 invoice that is 45 days overdue at 18% a year (1.5% a month) has accrued $110.96 of interest, making $5,110.96 due. Each further day adds $2.47.
Frequently asked questions
How do I calculate interest on an overdue invoice?
Multiply the invoice by the yearly rate, then by the days overdue divided by 365. $5,000 at 18% for 45 days is $110.96.
How much can I charge for a late payment?
Whatever your contract or invoice terms state, up to the limit your state allows. 1% to 1.5% a month is common. You generally cannot add a fee that the customer never agreed to.
Related calculators
Last reviewed: