What Is an Amortizing Loan?
When you borrow money with a fixed rate and fixed payment schedule, each payment is split between interest (what the lender earns) and principal (what reduces your balance). Early in the loan, a larger share goes to interest; later, more goes to principal — that pattern is amortization.
Unlike interest-only loans, an amortizing loan is designed to pay the balance to zero by the final payment (assuming no extra payments and no missed payments).
Monthly Payment Formula
For a standard fixed-rate loan, the periodic payment Pmt can be written as:
Pmt = L × [ r(1+r)^n ] / [ (1+r)^n − 1 ]
Where L is loan amount after any down payment, r is the periodic interest rate (annual rate ÷ payments per year), and n is total number of payments.
Example: $10,000 borrowed at 5% annual for 5 years, monthly payments:
- •Monthly rate
r = 0.05/12 - •
n = 60
Plugging in gives a payment of about $188.71 per month (rounded).
APR vs Interest Rate
| Term | Meaning |
|---|---|
| Nominal rate | The stated annual interest rate on the loan |
| APR | Annual Percentage Rate — often includes some fees, expressed as a yearly rate for comparison |
When comparing lenders, APR is usually the better apples-to-apples number for consumer loans, but always read what is included (origination fees, points, etc.).
How Extra Payments Save Money
Paying extra toward principal reduces the balance faster, so less interest accrues over time. Even small recurring extras can shave months or years off the loan and thousands in interest.
Some loans have prepayment penalties — rare on many standard mortgages today, but check your note.
How to Use This Loan Calculator
Enter your loan amount, interest rate, term, payment frequency, and optional down payment, extra payment, fees, and balloon if applicable. You'll see:
- •Payment amount and total interest
- •Amortization breakdown over time
- •Effect of extra payments on payoff date
All calculations run in your browser.
Shorter Term vs Lower Payment
| Choice | Effect |
|---|---|
| Longer term | Lower monthly payment, more total interest |
| Shorter term | Higher monthly payment, less total interest |
Use the calculator to compare side-by-side before you sign — the total interest difference between a 5-year and 7-year car loan can be substantial.