Equal Principal Amortization

The Equal Principal Amortization computes Monthly principal from 3 inputs: loan ($), annual rate (%), years. Amortization with equal principal payments.

Quick calculators for the math that shouldn’t need a notepad — instant, accurate, private to your browser. The Equal Principal Amortization sits in that toolkit — it amortization with equal principal payments. Enter your numbers above and the result updates instantly; every step of the math is shown in the Derivation panel so you can see exactly how the answer was reached.

Where

P

Loan ($)

r

Annual rate (%)

n

Years

Monthly principal

Output value

First month interest

Output value

First payment

Output value

1. 01Start by noting the input — Loan ($): 12000.
2. 02Start by noting the input — Annual rate (%): 5.
3. 03Start by noting the input — Years: 4.
4. 04Substitute these values into the formula: Monthly principal = e.P / (12 × e.n) | First month interest = e.P × e.r / 100 / 12 | First payment = t / (12 × e.n)+t × a / 100 …
5. 05Compute Monthly principal: the calculator returns 250.
6. 06Compute First month interest: the calculator returns 50.
7. 07Compute First payment: the calculator returns 300.
8. 08Cross-check the answer by opening the Derivation panel above — every line of math is shown so you can follow the computation end-to-end.

The formula gets rearranged depending on which variable you need. Here are the patterns you’ll run into in the real world — find the one that matches your problem and follow the worked steps.