Amortization schedule generator

An amortization schedule is a table that shows, payment by payment, how a fixed-rate loan is repaid. Each instalment is the same size, but early payments are mostly interest and later payments are mostly principal. Seeing the full table helps you understand the true cost of a loan and the effect of paying extra.

How to use the generator

1. Enter the loan amount, the annual interest rate and the term.
2. Choose the payment frequency, usually monthly.
3. Review the generated table: payment number, payment amount, interest portion, principal portion and remaining balance.

The formula behind it

The fixed payment is P = L × r / (1 - (1 + r)^-n), where L is the loan amount, r the periodic rate (annual rate divided by 12 for monthly payments) and n the number of payments. For every row, interest = balance × r, principal = P - interest, and the new balance = old balance - principal.

Worked example

A 200,000 loan at 6% for 30 years has r = 0.005 and n = 360, giving a monthly payment of about 1,199.10. In month 1 the interest is 1,000.00 and only 199.10 goes to principal. By month 300 the split has reversed, and over the whole term you pay roughly 231,676 in interest.

Tips

• Even small extra principal payments early in the loan cut total interest significantly, because they reduce the balance that every later interest charge is based on.
• Use the schedule to check a lender's figures; differences of a few cents per row are normal rounding.
• Variable-rate loans need a new schedule each time the rate changes.