Free Late Fee Calculator
The invoice was due weeks ago and the client has gone quiet. Before you send the next reminder, know the exact number: this late fee calculator counts the days overdue, applies your agreed rate, and gives you the figure to put in the message - in any currency, free, no sign-up.
Late fee formula: invoice amount × monthly rate × (days overdue ÷ 30). A $10,000 invoice 45 days late at 1.5% per month accrues $225. The fee is only enforceable if the client agreed to it up front, in the contract or the invoice terms.
Percentage fees are simple interest, prorated daily (a month counted as 30 days, a year as 365). 1.5% per month is the common commercial convention; use whatever your invoice terms actually say.
A late fee is only enforceable if the client agreed to it up front - in your contract or on the invoice terms - and some countries cap the rate. The fee is leverage; the goal is still the payment.
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Can you actually charge it? Rules by region
The universal rule: a late fee holds up when the client agreed to it before the work started. Put the clause in your contract and repeat it on every invoice. Beyond that, jurisdictions differ:
- UK: B2B invoices carry statutory interest even without a clause - 8% plus the Bank of England base rate under the Late Payment of Commercial Debts Act, plus a fixed recovery sum (£40, £70, or £100 depending on the debt size). With a 4% base rate, a £5,000 invoice 45 days late accrues about £74 of interest plus the £70 fixed sum.
- EU: the Late Payment Directive gives a similar statutory scheme for commercial debts - reference rate plus at least 8 points.
- US: contractual, and several states cap the rate (that's why so many US invoices standardize on 1.5% per month). Check your state before printing a higher number.
- Nigeria and most other markets: whatever the contract says, enforced as a contract term - which is exactly why the clause needs to be on the invoice, not in your head.
A clause that works on most invoices: "Payment due within 14 days of the invoice date. Overdue balances accrue a late fee of 1.5% per month, prorated daily."
The fee is leverage - the reminder collects
Most late invoices aren't refusals; they're disorganization on the client's side. A polite reminder on day 3 clears many of them, a firmer one on day 14 clears more, and the late fee belongs in the final notice - stated as a fact with the exact figure from this calculator, not as a threat. Copy the breakdown above straight into the message, or let the Payment Reminder Generator write the whole sequence for you.
Late Fee FAQ
How do I calculate a late fee on an invoice?
Multiply the invoice amount by the agreed rate, prorated for how late it is: amount × monthly rate × (days late ÷ 30). A $10,000 invoice that's 45 days overdue at 1.5% per month accrues $10,000 × 0.015 × 1.5 = $225. Enter your own figures above and the calculator handles the proration.
Can I legally charge late fees?
Generally yes for business-to-business invoices, but the fee must have been agreed up front - in your contract or the invoice terms the client accepted. Some jurisdictions also cap the rate, and a few give you statutory interest even without a clause: in the UK, B2B debts attract 8% plus the Bank of England base rate under the Late Payment of Commercial Debts Act, plus a fixed recovery sum of £40-£100. When in doubt, check your jurisdiction's rules before adding a fee to an invoice.
What is a reasonable late fee?
1% to 2% per month is the common commercial range, with 1.5% the convention on many invoices. Higher rates rarely survive a dispute and sour the relationship. The fee's real job isn't revenue - it's making 'I'll pay next month' cost something, so paying on time becomes the easy choice.
What do Net 30 and 2/10 Net 30 mean?
Net 30 means the full amount is due 30 days after the invoice date. 2/10 Net 30 adds an early-payment discount: 2% off if paid within 10 days, otherwise the full amount by day 30. Discounts for early payment often move cash faster than fees for late payment - consider offering both.
Should I charge a late fee or just send reminders?
Both, in that order. A reminder collects most late invoices - many are late from disorganization, not refusal. The fee clause is your leverage for the rest: mention in the final reminder that late fees have started accruing, with the exact figure. Our free Payment Reminder Generator writes those messages for you, friendly through final notice.
How is this different from a Growpins Ledger account?
This calculator handles one overdue invoice at a time. Growpins Ledger tracks the status of every invoice you issue - who's paid, who's overdue and by how long - so you see the problem before it's 45 days old. Free tier, no card required.
Stop finding out at day 45
Growpins Ledger tracks every invoice you issue - who's paid, who's overdue and by how many days - so the reminder goes out at day 3, not after the money is six weeks late. Built by the team behind Growpins, founded by Dokun Bamigboye. Free tier, no card required.
Get Started FreeNeed the invoice itself? Use the Free Invoice Generator, or browse all free tools.
This page is general information, not legal advice. Late fee enforceability and caps vary by jurisdiction and contract - confirm your position before adding fees to an invoice.