Late Fee Calculator

How to use this calculator

1. Enter your invoice amount — the original amount the client owes.
2. Set the due date — when payment was supposed to arrive.
3. Set the payment date — when it was actually paid (or leave blank for today).
4. Choose your fee type — percentage per month is the most common. Fixed per day or per week also works.
5. See your result — the late fee and total amount owed, calculated instantly.

What's a reasonable late fee?

The standard late fee is 1.5% per month (18% annually). This is the most commonly used rate and is legally permissible in most US states and many other jurisdictions.

Some freelancers charge a flat amount per day (e.g., $25/day for invoices over $1,000) — this is simpler to understand and calculate. Whatever rate you choose, include it in your contract before work begins. A late fee that appears for the first time on an overdue invoice is much harder to enforce.

Do I need to include late fees in my contract?

Yes — and you should. A late fee clause in your contract serves two purposes: it incentivises on-time payment, and it gives you a legal basis to charge the fee if payment is late. Learn more in our guide on freelance contract templates.