What this calculator does
An amortization calculator shows how a fixed-rate loan gets paid off over time. Enter your loan amount, interest rate, and term, and it works out your fixed monthly payment, then splits every payment into two parts: how much covers interest and how much pays down your balance. You also get a full amortization schedule, so you can watch your balance shrink month by month until it reaches $0.00.
Enter the loan amount
Type in the total you are borrowing, for example $20,000.00. This is your starting principal.
Add the interest rate
Enter the annual interest rate (APR) your lender quoted, such as 6.0%. The calculator converts this to a monthly rate for you.
Set the loan term
Choose how long you will repay, in years or months. A common auto loan term is 5 years, or 60 monthly payments.
Pick a start date (optional)
Add the date of your first payment if you want the schedule to line up with real calendar months.
Add extra payments (optional)
If you plan to pay a little more each month, enter it here to see how much interest and time you save.
Review your results
The calculator shows your monthly payment, total interest, total cost, and the full payment-by-payment schedule.
How amortization works
A loan amortization calculator turns three numbers, your loan amount, rate, and term, into one fixed monthly payment, then divides each payment between interest and principal. Each month, the interest that built up is covered first, and whatever is left pays down your principal. Because your balance is largest at the start, early payments are mostly interest. As the balance falls, more of each payment goes to principal, even though the total payment stays the same.
The payment comes from a standard formula: payment = P x r x (1 + r)^n / ((1 + r)^n - 1), where P is the loan amount, r is the monthly interest rate (annual rate / 12), and n is the number of payments.
Worked example: Say you borrow $20,000.00 at 6.0% for 5 years (60 payments). The monthly rate is 0.5% (6.0% / 12). Plug those in and the payment comes to about $386.66 per month. In month one, interest is $20,000.00 x 0.5% = $100.00, so $286.66 goes to principal and your balance drops to $19,713.34. By the last payment, nearly the entire amount goes to principal. Over the full term you would pay about $3,200.00 in total interest.
Reading your amortization schedule
An amortization schedule calculator like this one gives you more than a single monthly figure. Scroll through the schedule and you will see four columns for each month: the payment, the interest portion, the principal portion, and the remaining balance. Early rows lean heavily on interest, later rows lean on principal, and the final row brings your balance to $0.00. Reading it this way helps you see how much sooner you would be debt-free with a bit extra each month, or how much a lower rate would save.
Costs and factors to plan for
Your monthly payment rests on three things: how much you borrow, the interest rate, and the term. A longer term lowers the monthly payment but raises the total interest you pay over the life of the loan. A higher rate does the same. Also watch for extras a basic calculator may not capture, like origination fees that get rolled into the loan, or insurance and taxes your lender bundles in. When you compare offers, the APR is usually a fairer measure than the interest rate alone, because it folds in many of these fees.
Tips to get more from the schedule
Compare two terms side by side. A 5-year loan costs less in interest than a 7-year loan at the same rate, even though the monthly payment is higher.
Try a small extra payment. Adding even $25.00 a month to principal can shave months off the loan and cut total interest.
Look for the crossover point, the month where the principal portion of a payment finally passes the interest portion.
Confirm your lender applies extra payments to principal, not to future interest, so the savings actually show up.
Use the same APR for every loan you compare so the numbers line up fairly.
Frequently asked questions
What is an amortization schedule?
An amortization schedule is a table that lists every loan payment from the first to the last. For each payment it shows how much goes to interest, how much goes to principal, and your remaining balance. It lets you see exactly when the loan will be fully paid off.
How is loan amortization calculated?
The calculator finds a fixed monthly payment from your loan amount, monthly interest rate, and number of payments. Each month it charges interest on the current balance first, then puts the rest of the payment toward principal. As the balance drops, the interest portion shrinks and the principal portion grows.
Why does most of my early payment go to interest?
Interest is charged on your outstanding balance, which is highest at the start of the loan. So your first payments cover a large interest charge and leave less for principal. As you pay the balance down, the interest charge falls and more of each payment reduces what you owe.
Do extra payments change my amortization schedule?
Yes. When you pay extra and the money is applied to principal, your balance falls faster, which lowers future interest charges and shortens the loan. Even small, regular extra payments can save a meaningful amount over the full term. Enter an extra amount in the calculator to see the effect.
Can I use this for a mortgage, car loan, or student loan?
Yes. The same amortization math applies to most fixed-rate installment loans, including mortgages, auto loans, and personal loans. Just enter that loan's amount, rate, and term. Keep in mind that mortgages often add property taxes and insurance, which this calculator does not include.