Free Late Fee Calculator
Estimate simple or compound interest on overdue balances from due date to today — useful for transparent payment conversations.
Calendar days past due
0
Accrual days (after grace)
0
Late fee
$0.00
Total owed (outstanding + fee)
$1,000.00
Outstanding balance: $1,000.00
📅 Escalation guide
- Day 0: Invoice sent (due 2026-09-05)
- Day ~5: Friendly reminder
- Day ~15: Mention late fee
- Day ~30: Formal notice
- Later: Demand letter generator
Fee projection
| Scenario | Late fee | Total owed |
|---|---|---|
| Current (0 calendar days past due) | $0.00 | $1,000.00 |
| If 30 calendar days past due | $14.79 | $1,014.79 |
| If 60 calendar days past due | $29.59 | $1,029.59 |
| If 90 calendar days past due | $44.38 | $1,044.38 |
| If 120 calendar days past due | $59.18 | $1,059.18 |
What is a free late fee, and what goes on one?
The late fee calculator computes the interest or penalty amount a client owes on an overdue invoice, based on your stated late fee percentage and the number of days past due.
Key components
- Original invoice amount — the base amount owed.
- Late fee rate — percentage or flat fee per period.
- Days overdue — how late the payment is.
- Total owed — original amount plus calculated late fees.
How to use this tool
- Enter the original invoice amount.
- Input the number of days the payment is overdue.
- Set the interest rate agreed upon in your contract.
- Generate the updated total including the accrued late fees.
Why this matters
Enforcing late fees trains clients to respect your deadlines. This tool removes the emotion from the process by calculating the exact contractual penalty owed.
Works well with
Frequently asked questions
Enforceability depends on your contract, jurisdiction, and consumer rules. Disclose terms early and keep rates reasonable and documented.
Simple interest accrues on the principal only; compound accrues on principal plus accumulated interest over periods. Your policy should state which applies.
Sometimes. Pair waivers with faster payment or updated terms. The calculator still helps you show what the fee would have been for clarity.
A flat administrative charge plus interest on the outstanding balance — some contracts use both so small invoices still cover admin time.
They delay when interest or fees start counting after the due date, matching contract language like “fees begin after a five-day grace period”.
Yes — enter the principal still outstanding so accruals reflect what remains unpaid after deposits or installments.
It shows fee growth at common aging buckets (for example 30/60/90 days) so you can explain totals in collections conversations.
You copy defensible figures from this tool into correspondence; always match the method and rate your signed terms describe.