Free tool
Late fee calculator
Estimate a late payment fee from invoice amount, days overdue, annual interest rate, and an optional flat fee. Numbers stay on your device — nothing is saved.
Inputs
Formula: interest ≈ amount × (annual rate) × (days ÷ 365), plus any flat fee. Rounded to the nearest cent. This is an estimate for planning — not legal advice, and not a claim about maximum permitted rates.
Estimate
- Interest
- $19.73
- Flat fee
- $25.00
- Total late fee
- $44.73
- New total due
- $1,044.73
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