Late Fee Calculator

Calculate late payment fees: flat fee or monthly percentage on overdue invoices.

Invoice amount ($):

Days late:

Fee type:

Fee value:

Check your contract — some regions cap late fees. Estimates only.

How to use

Enter the invoice amount, days late and fee terms, then click Calculate. Everything runs in your browser — nothing is uploaded or stored.

Flat or percentage?

Choose either a fixed fee or a monthly % of the invoice amount.

How are partial months handled?

The monthly rate is prorated by days late ÷ 30.

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