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Late Payment Fee Calculator
Estimate simple interest on an overdue invoice using the balance, annual rate and number of days late.
How the late payment calculator works
This tool estimates simple interest using: overdue balance × annual rate × days late ÷ 365. It is a planning calculator, not a determination of what you are legally entitled to charge.
Check your contract first
Before adding a late fee to an invoice, check your contract, invoice terms and applicable local rules. Some agreements require a specific fee structure or notice.
Example
If a $1,000 balance is 30 days late at an 8% annual simple rate, the estimated interest is about $6.58.