Amortisation Calculator — Step-by-Step Solutions
The Amortisation Calculator generates detailed payment schedules showing how each payment splits between principal and interest over the life of a loan. It supports four modes: full amortisation schedule, extra payment impact analysis, payoff date calculation, and total interest comparison.
Enter your loan details to see a month-by-month or year-by-year breakdown. The extra payment mode shows how additional payments can reduce your total interest and shorten the loan term.
Your calculations will appear here
How to Use the Amortisation Calculator
- Enter the loan amount, annual interest rate, and loan term in years.
- Select a mode: Amortization Schedule, Extra Payment Impact, Payoff Date, or Total Interest Paid.
- For Extra Payment Impact or Payoff Date modes, enter an additional monthly payment amount.
- For Payoff Date mode, also enter the loan start year and month.
- Browse the paginated amortization table to see the month-by-month breakdown of each payment.
Formula and Theory
An amortization schedule breaks down each monthly payment into its principal and interest components. Early in the loan, most of each payment covers interest. Over time, the interest portion shrinks and the principal portion grows as the outstanding balance decreases.
For each month, the interest portion equals the remaining balance multiplied by the monthly rate: Interest = Balance * (rate / 12). The principal portion is the monthly payment minus the interest: Principal = Payment - Interest. The new balance is the previous balance minus the principal paid.
Extra payments go entirely toward reducing the principal, which decreases future interest charges. Even modest extra payments can save thousands in interest and shorten the loan by months or years.
The total interest paid over the life of a loan can be substantial. On a 30-year mortgage, total interest often exceeds the original loan amount. The amortization table makes this cost visible and helps borrowers make informed decisions.
Worked Examples
Example 1: First month of a mortgage
Problem: For a 200,000 loan at 6% over 30 years, what is the first month breakdown?
Solution: Monthly payment = 1,199.10. First month interest = 200,000 * 0.005 = 1,000. Principal = 1,199.10 - 1,000 = 199.10.
Answer: Month 1: 1,000 interest, 199.10 principal, balance 199,800.90
Example 2: Extra payment savings
Problem: On a 250,000 loan at 5% over 30 years, how much does an extra 200/month save?
Solution: Without extra: 360 months, total interest 233,139. With extra: approximately 282 months, total interest 173,684.
Answer: Save approximately 59,455 in interest and pay off 6.5 years early
Example 3: Payoff date calculation
Problem: A 150,000 loan at 4.5% for 20 years starting January 2026. When does it pay off?
Solution: 20 years * 12 = 240 payments. January 2026 + 240 months = January 2046.
Answer: Payoff date: January 2046
Frequently Asked Questions
What is an amortization schedule?
Why does most of the early payment go to interest?
How do extra payments help?
Is there a difference between amortization and depreciation?
Related Finance Calculators
Mortgage Calculator
Calculate monthly mortgage payments, total interest, and amortisation schedules. Compare refinance options and find how much you can afford.
Compound Interest Calculator
Calculate compound interest with contributions. Compare compounding frequencies, find time to target, and see year-by-year growth tables.
Margin Calculator
Calculate profit margin, markup, and selling price. Convert between margin and markup percentages. Compare gross and net margins. Free online margin calculator.
Sales Tax Calculator
Calculate sales tax, find pre-tax prices, and compare tax rates. Includes US state tax rate reference table. Free online sales tax calculator.
Discount Calculator
Calculate sale prices, find discount percentages, and work out stacked discounts. See how much you save. Free online discount calculator.
Inflation Calculator
Calculate purchasing power, inflation rates between years, and future value adjusted for inflation. US CPI data from 1913 to 2025. Free online inflation calculator.