Free Late Payment Interest Calculator

WHAT IT IS
A single-file calculator that works out late interest on an overdue invoice from the amount, due date and annual rate.

WHAT'S INSIDE
Late_Payment_Interest_Calculator.html (single file, works offline).

HOW TO USE (5 STEPS)
1. Open the main file in its folder.
2. Replace every bracket field or EXAMPLE row with your own details.
3. Save a copy for each client or week before you start editing.
4. Use it on a real job, not just as a sample.
5. Keep the finished copy with the project file.

REQUIREMENTS
Any modern web browser; no internet connection needed. Opens as a single file.