APR Calculator Application

Calculate complex loans using the United States Rule method of accrual. This tool is designed for compliance professionals who need accurate loan calculations for regulatory compliance and disclosure of loan terms.

Python Flask HTML CSS JavaScript

Features

US Rule Calculation
Calculates loan payment schedule based on the United States Rule method, where interest is calculated only on the unpaid principal balance.
Detailed Schedule
Displays a comprehensive payment schedule with period-by-period breakdown of principal, interest, and remaining balance.
APR Calculation
Accurately calculates the Annual Percentage Rate based on the loan terms and origination fee.
Responsive Design
Fully responsive web interface that works on desktop, tablet, and mobile devices.

How It Works

The APR calculator follows the United States Rule method for calculating loan amortization and APR:

  1. Interest is calculated only on the unpaid principal balance
  2. Payments are applied first to interest, then to principal
  3. Unpaid interest is not capitalized (no compounding of interest-on-interest)
  4. The process is repeated for each payment period

When an origination fee is present, it is added to the amount financed to determine the starting principal for payment calculations, but the original amount financed is used as the period 0 outflow for APR calculations.