Amortization Schedule Calculator
This is the schedule tool, not another monthly-payment tool. It gives you one row per payment period showing interest, principal, running totals and the balance still owed, for the whole life of a fixed-rate loan.
Your schedule will appear here
Enter a loan amount, rate and term, then build the schedule to see every payment split into interest and principal.
This is the schedule tool, not a payment tool
Amortization schedule vs. our Loan, Mortgage and Auto Loan calculators: those three are monthly-payment tools. You put your figures in and get one number back, plus totals. This page is the schedule: a row per payment period with interest, principal, cumulative totals and the balance left, along with a full table built for exporting.
Just want to know what the monthly payment will be? Use the Loan Calculator, Mortgage Calculator or Auto Loan Calculator.
Against our Debt Payoff Calculator: that one is about strategy and ordering when you are juggling several debts. Amortization describes one loan with a fixed payment schedule.
Careful: two different meanings of “amortization”
In accounting, amortization has a second meaning: spreading the cost of an expensive, long-lived item over several periods, usually something intangible such as a patent. Depreciation covers tangible property instead, things like cars, buildings and machinery. This page is about loan schedules, not that accounting sense. For the asset side, use our Depreciation Calculator.
Quick Answer
An amortization schedule breaks each loan payment into the interest charged that period and the principal it repays. The payment comes from PMT = [r + r/((1+r)^t - 1)] x P, where r is the annual rate divided by 12 and t is the term in months. Interest for any period equals the outstanding balance times r, so the interest share falls and the principal share rises as the loan winds down.
How It Works: Formula & Variables
The monthly payment
PMT = [r + r/((1+r)t − 1)] × P
- PMT
- The monthly payment.
- P
- The principal, meaning the amount borrowed.
- r
- The annual rate as a decimal, divided by 12. A 6% loan gives r = 0.005.
- t
- The term in months. Twenty years is 240.
How each payment splits
Payment = Principal portion + Interest portion
Interest (period k) = outstanding balance × r
Principal (period k) = PMT − Interest
Interest is computed on the current amount owed and thus will become progressively smaller as the principal decreases. The remainder of the payment goes toward reducing the principal amount owed. So the portion of the payment applied toward the principal increases over time, and the portion applied to interest decreases because you owe less principal.
The fixed-principal variant
There is a second style of schedule where the principal amount remains the same as the loan is paid off. The interest charged decreases, so the monthly payment also decreases. You pay more at the start and less later, and you pay less interest overall. Switch the schedule type in the calculator to see it.
What a basic schedule leaves out
Worth knowing before you rely on any schedule, ours included: “Basic amortization schedules do not account for extra payments... amortization schedules generally do not consider fees. Generally, amortization schedules only work for fixed-rate loans and not adjustable-rate mortgages, variable rate loans, or lines of credit.”
Our calculator does handle extra payments, since that is the single most useful thing to model. Fees and variable rates stay outside the schedule, so treat the output as the loan's interest mechanics rather than its full cost. For the cost including fees and points, see the APR side of our APR/APY Calculator.
Warning: negative amortization
Negative amortization means that even when you pay, the amount you owe will still go up because you are not paying enough to cover the interest. It shows up on loans with minimum-payment options and on some student loan arrangements. A normal amortization schedule assumes this never happens, because the payment is set high enough to clear the interest and then some. If your statement balance is climbing while you are making payments, the schedule below does not describe your loan.
Worked Examples
Example 1: £100,000 at 6% over 20 years
P = 100,000, r = 0.005 (that is 6 / 100 / 12), and t = 240 months. PMT = [0.005 + 0.005/(1.005240 − 1)] × 100,000 = £716.43 per month.
Add £100 a month on top and the loan finishes 49 months earlier, with £16,788 less interest paid. That is the whole argument for overpaying in one line.
Example 2: a $25,000 car loan, payment by payment
$25,000 at 6.9% over 60 months. r = 0.00575, which gives a payment of $493.85. Here is how the first three months break down.
| Month | Interest | Principal | Balance |
|---|---|---|---|
| 1 | $143.75 | $350.10 | $24,649.90 |
| 2 | $141.74 | $352.11 | $24,297.78 |
| 3 | $139.71 | $354.14 | $23,943.65 |
The payment never moves, but the interest column drops by about two dollars every month while the principal column climbs by the same amount. Across all 60 payments the total comes to $29,631.08, of which $4,631.08 is interest.
Key Concepts
The split moves, the payment does not: on a standard schedule the monthly total is level for the whole term, while the interest and principal portions trade places month by month.
Interest tracks the balance: every period's interest is just the outstanding balance times the monthly rate. That single line explains the entire shape of the schedule.
Front-loading is arithmetic, not a trick: lenders are sometimes accused of stacking interest at the start. Nothing is being stacked. The balance is simply at its largest then.
Extra payments compound backwards: money put against the principal today removes the interest it would have generated in every remaining month, which is why small overpayments early on do so much work.
Common Mistakes
Expecting the interest portion to stay flat: it falls every single period, because it is charged on a balance that keeps shrinking. Only the total payment holds steady.
Running a schedule on a variable-rate loan: amortization schedules only work for fixed-rate loans. Adjustable-rate mortgages, variable rate loans and lines of credit will drift away from any table you build.
Assuming fees are in there: a basic schedule ignores fees entirely, so the total paid at the bottom is not the full cost of the borrowing.
Frequently Asked Questions
Paying off a loan with regular payments, so that the amount you owe goes down with each payment. Every payment covers the interest that has built up since the last one, and whatever is left over reduces the balance.
Interest is computed on the current amount owed, and at the start of a loan that figure is at its highest. As the principal comes down, so does the interest charge, which frees up more of each payment to attack the balance.
On a standard amortized loan, yes. There is a second style where the principal portion stays fixed instead. On that one the principal amount remains the same as the loan is paid off, the interest charged decreases, and so the monthly payment also decreases.
Most auto loans and mortgages. Credit cards are revolving debt and do not amortize, and neither do interest-only or balloon loans, where the balance does not steadily wind down to zero through the regular payment.
Quite a lot. On a £100,000 loan at 6% over 20 years, adding £100 a month clears the debt 49 months early and saves £16,788 in interest, because every extra pound goes straight at the principal and stops earning interest for the lender.
Negative amortization means that even when you pay, the amount you owe will still go up because you are not paying enough to cover the interest. The shortfall gets added back onto the balance instead of coming off it.
Related Calculators
Loan Calculator
Monthly payment, total interest and payoff time on any fixed-rate loan.
Mortgage Calculator
Monthly mortgage payment including taxes, insurance, PMI and HOA fees.
Auto Loan Calculator
Car payment with trade-in, sales tax and fees, or the price you can afford.
Debt Payoff Calculator
Snowball and avalanche strategies across several debts at once.
APR / APY Calculator
Convert a nominal rate into APY, or into a cost-inclusive APR with points and fees.
Depreciation Calculator
Straight-line, declining balance, DDB and sum-of-years-digits schedules for an asset.
Sources
- TheCalculatorSite, Amortization Calculator (the PMT formula and the £100,000 worked example): https://www.thecalculatorsite.com/finance/calculators/amortization-calculator.php
- calculator.net, Amortization Calculator (per-period interest and principal, and the limitations of basic schedules): https://www.calculator.net/amortization-calculator.html
- CalculatorSoup, Amortization Schedule Calculator (the shifting principal share and the fixed-principal variant): https://www.calculatorsoup.com/calculators/financial/amortization-schedule-calculator.php
- Consumer Financial Protection Bureau, what is negative amortization (definitions of amortization and negative amortization): https://www.consumerfinance.gov/ask-cfpb/what-is-negative-amortization-en-103/