Online Receipt Generator
Payment Terms & Late Payments

Late Payment Fee Calculator

Calculate late fees charged monthly, weekly, daily or once — by dates or number of periods, with compounding, grace period and a cap.

Result

Days late

0 days

Fees charged

0

Total late fees

$0.00

As % of the original amount

0%

Total now due

$1,000.00

Embed this calculator on your site

Copy this code and paste it into your page's HTML. The calculator is free to use and resizes itself to fit.

How it's calculated

A fee is charged for every period that has started after the due date (plus any grace period) — paying one day into a new month incurs that month's fee. Simple: each fee is the rate × the original amount (5% a month for 12 months = 60%). Compound: each fee is charged on the amount plus earlier fees (≈ 79.6%). An optional cap limits the total.

This late payment fee calculator adds up the fees on an overdue invoice. Charge a percentage or a fixed amount, every month, week or day, or once. Enter dates or a number of late periods. A cap and a grace period are optional.

The formula

Simple:    fee per period = invoice amount x fee rate
Compound:  fee per period = (invoice amount + earlier fees) x fee rate
Fixed:     fee per period = fixed fee amount
total fees = sum of the fees, never more than the cap
new total  = invoice amount + total fees
effective rate = total fees / invoice amount x 100

The cap is a percent of the invoice. With dates, a fee is charged for every period that has started after the due date plus grace days.

Worked example

Counting periods. Invoice $1,000. Fee 1.5% monthly, simple. 3 periods late.

  • Fees: 15 + 15 + 15 = $45.00
  • Total now due: $1,045.00
  • As % of the original amount: 4.5%

Using dates. Invoice $1,000. Fee 5% monthly. Due 2026-01-15. Paid 2026-04-20. No grace days.

  • Days late: 95
  • Fees charged: 4 (on 01-16, 02-16, 03-16 and 04-16)
  • Total late fees: $200.00
  • Total now due: $1,200.00
  • As % of the original amount: 20%

How to read the result

Look at "As % of the original amount". A small monthly rate builds up fast. A 5% monthly fee is 60% over a year.

The period count is the most common surprise. Four fees for 95 days looks high, but the fee period began four times. Add a grace period if you want a softer rule.

Use "Compound" only if your agreement says fees can be charged on fees. Simple is easier to explain and to defend.

A cap protects the relationship with the customer. It can also be required. Late fee limits vary by country, state and customer type. Confirm them with a legal adviser before you write terms.

Put the fee rate, the frequency and the grace period on every invoice. Fees you did not state are hard to collect.

Related tools

To see the statutory rate where your client is based, check our table of late payment interest rates by country, with official sources for each country.

Frequently asked questions

How do I calculate a late payment fee?
Multiply the invoice amount by the fee rate for each late period, then add the fees. A $1,000 invoice with a 1.5 percent monthly fee, 3 months late, has fees of $45.
How many fees are charged if I pay one day into a new month?
One more. The calculator charges a fee for every period that has started after the due date and grace period. Paying one day into a new month already incurs that month's fee.
What is the difference between simple and compound late fees?
Simple fees use the original amount each time. Compound fees use the amount plus earlier fees. Over 12 months at 5 percent, simple gives 60 percent and compound gives about 79.6 percent.
What is a grace period?
It is a set number of days after the due date when no fee applies. The first fee starts after the grace days end. Write the grace period on the invoice.
Is there a limit on late fees?
Many places limit late fees by law or by contract. Rules vary by country and by type of customer. Check with a legal adviser. The cap field lets you set a maximum as a percent of the invoice.