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Amortization Calculator: Loan Schedule and Extra Payments
See how every payment on a fixed-rate loan splits between interest and principal. Add an optional extra monthly payment to see how much sooner you finish and how much interest you avoid.
What amortization means
To amortize a loan is to pay it off gradually in scheduled instalments. With a fixed-rate loan, the payment stays level, but its makeup changes every month. Each month, the interest is the balance times the monthly rate. Whatever is left of the payment reduces the balance. Next month the balance is lower, so the interest is slightly lower and the principal slightly higher.
The monthly rows in the table show this directly. In month 1 of a 200,000 loan at 6%, the interest is 1,000 and only about 199 goes to principal. The proportion shifts slowly at first and faster in the later years.
How extra payments work
An extra payment goes entirely to principal, because the interest for the month has already been covered. A lower balance then produces less interest next month, so the same regular payment now removes more principal. The effect compounds, which is why a modest extra amount can shorten a long loan by years. The saving shown is the difference in total interest between the plan with extras and the plain schedule.
Before paying extra, confirm that your lender applies surplus to principal rather than to future instalments, and that there is no prepayment charge. For one-off lump sums, use the mortgage payoff calculator.
Reading the schedule
| Column | Meaning |
|---|---|
| Payment | Interest plus principal for that period, including any extra. |
| Principal | The part that reduces what you owe. |
| Interest | The charge for borrowing during that period. |
| Balance after | What remains owing once the payment is made. |
The first 24 rows are monthly so that you can see the early split in detail. After them, each row sums a full year. The final year may be shorter if extra payments clear the loan early.
Assumptions
The schedule assumes a fixed rate, equal monthly payments, interest charged on the balance at the monthly rate and no fees. Lenders may round each payment to the nearest cent, which changes the final payment by a few cents. Adjustable-rate loans, interest-only periods and daily-interest loans will differ. Use the schedule to understand the structure of your loan and compare strategies, then rely on your lender's statement for exact figures.
One way to read the year totals: the interest column is largest in year 1 and shrinks each year, while the principal column does the opposite. The crossover, where a year's principal first exceeds its interest, comes well into a thirty-year loan at typical rates but much sooner on a shorter one. Changing the term from 30 to 15 years and comparing the interest totals is a quick way to see how much of a long loan's cost comes from time.
Worked example
A 250,000 loan at 6.5% over 30 years with 200 added to the payment each month.
Inputs
| Loan amount | 250000 |
|---|---|
| Annual interest rate | 6.5 % |
| Loan term | 30 years |
| Extra payment each month | 200 |
Result
Regular payment 1,580.17 plus 200.00 extra.
| Regular monthly payment | 1,580.17 |
|---|---|
| Total interest with this plan | 221,243.10 |
| Months to pay off | 265 (22 years 1 months) |
| Interest saved by the extra payments | 97,618.12 |
| Months saved | 95 |
First 24 months, then totals for each year
| Period | Payment | Principal | Interest | Balance after |
|---|---|---|---|---|
| Month 1 | 1,780.17 | 426.00 | 1,354.17 | 249,574.00 |
| Month 2 | 1,780.17 | 428.31 | 1,351.86 | 249,145.69 |
| Month 3 | 1,780.17 | 430.63 | 1,349.54 | 248,715.05 |
| Month 4 | 1,780.17 | 432.96 | 1,347.21 | 248,282.09 |
| Month 5 | 1,780.17 | 435.31 | 1,344.86 | 247,846.78 |
| Month 6 | 1,780.17 | 437.67 | 1,342.50 | 247,409.12 |
| Month 7 | 1,780.17 | 440.04 | 1,340.13 | 246,969.08 |
| Month 8 | 1,780.17 | 442.42 | 1,337.75 | 246,526.66 |
| Month 9 | 1,780.17 | 444.82 | 1,335.35 | 246,081.84 |
| Month 10 | 1,780.17 | 447.23 | 1,332.94 | 245,634.61 |
| Month 11 | 1,780.17 | 449.65 | 1,330.52 | 245,184.96 |
| Month 12 | 1,780.17 | 452.08 | 1,328.09 | 244,732.88 |
Financial disclaimer: Results are estimates for planning and education. They are not financial, tax or legal advice. Fees, taxes, rates and rules vary by lender, product and country, so confirm figures with your provider or a qualified adviser before making decisions.
Frequently asked questions
What is an amortization schedule?
It is a table listing each loan payment, how much of it is interest, how much reduces the balance and what you still owe afterwards.
Why is so much of my early payment interest?
Interest is charged on the balance, and the balance is highest at the start. As it falls, the interest portion shrinks and the principal portion grows.
How much do extra payments save?
It depends on the rate, the term and the timing. Enter your own figures above; the results show the interest saved and the months removed.
Does the schedule show the final payment exactly?
The last payment is adjusted to clear the balance. Your lender may differ by a few cents because of rounding.
Can I use this for a car loan or personal loan?
Yes. Any fixed-rate loan with equal monthly payments follows the same schedule.
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References and sources
- Level-payment amortization formula as taught in introductory finance texts.
- Consumer Financial Protection Bureau: educational guides on loan repayment. Link