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Amortization Calculator

Free Amortization Calculator - calculate instantly with our online tool. No signup required. Accurate mortgage calculations with real-time results.

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Reviewed & Methodology

Every calculator is built using industry-standard formulas, validated against authoritative sources, and reviewed by a credentialed financial professional. All calculations run privately in your browser - no data is stored or shared.

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How to Use the Amortization Calculator

  1. 1. Enter your values - fill in the input fields with your numbers.
  2. 2. Adjust settings - use the sliders and selectors to customize your calculation.
  3. 3. View results instantly - calculations update in real-time as you change inputs.
  4. 4. Compare scenarios - adjust values to see how changes affect your results.
  5. 5. Share or print - copy the link, share results, or print for your records.

Amortization Calculator

This amortization calculator computes your monthly loan payment, total interest paid, and total cost for any fixed-rate loan. It also generates a full amortization schedule showing how each payment is split between principal and interest over the life of the loan — helpful for mortgages, car loans, and personal loans.

How Amortization Is Calculated

The monthly payment for a fully amortizing loan is computed with the standard annuity formula:

M = P x [r(1 + r)^n] / [(1 + r)^n - 1]

Where P is the loan principal, r is the monthly interest rate (annual rate / 12 / 100), and n is the total number of monthly payments (years x 12). Each month, interest is charged on the remaining balance, and the rest of the payment reduces the principal.

Example

Loan AmountInterest RateTermMonthly PaymentTotal InterestTotal Paid
$250,0006.5%30 yr$1,580$319,000$569,000
$250,0006.5%15 yr$2,178$142,000$392,000
$400,0007.0%30 yr$2,661$558,000$958,000
$150,0005.0%20 yr$990$87,500$237,500

Key Factors That Affect Amortization

  • Interest rate — even a 0.5% difference on a $300,000 loan changes total interest by roughly $30,000 over 30 years
  • Loan term — shorter terms have higher monthly payments but dramatically lower total interest
  • Principal amount — interest is computed on the remaining balance, so a larger loan compounds more interest
  • Extra payments — even small additional principal payments early in the loan significantly reduce total interest
  • Payment frequency — biweekly payments effectively add one extra monthly payment per year

Tips

  1. Compare 15-year and 30-year terms side by side — a 15-year mortgage typically saves over 50% in total interest
  2. In the early years of a 30-year loan, roughly 70-80% of each payment goes to interest; this ratio flips over time
  3. Making one extra payment per year on a 30-year mortgage can shorten the loan by about 4-5 years
  4. Print the full amortization schedule to track exactly when your loan crosses the halfway point on principal

Frequently Asked Questions

What is an amortization schedule?
An amortization schedule is a table showing every payment over the life of a loan, broken down into principal and interest portions. Early in the loan, most of each payment goes to interest. Over time, the principal portion grows as the balance shrinks. This schedule helps you see exactly when you will reach milestones like the halfway point on principal.
Why do I pay so much interest at the beginning of my loan?
Interest is calculated on the remaining balance each month. At the start of a 30-year, $300,000 loan at 6.5%, your balance is at its highest, so roughly 75-80% of each payment goes to interest. As you pay down the balance, less interest accrues each month and more of your payment goes to principal. This is the fundamental nature of amortization.
How does loan term affect total interest paid?
Dramatically. A $250,000 loan at 6.5% costs about $319,000 in interest over 30 years versus $142,000 over 15 years -- a difference of $177,000. The shorter term has higher monthly payments ($2,178 vs $1,580) but saves over 55% in total interest. The amortization schedule makes this tradeoff visible month by month.
Can I use this calculator for car loans and personal loans?
Yes. The amortization formula works for any fixed-rate, fully amortizing loan -- mortgages, car loans, personal loans, and student loans. Enter the loan amount, annual interest rate, and term in years. The calculator will generate a complete payment schedule showing principal and interest for each period.
How do extra payments affect my amortization schedule?
Extra payments go directly to principal, which reduces the balance that future interest is calculated on. Even small extra payments early in the loan have an outsized effect because they prevent years of compounding interest. Making one extra payment per year on a 30-year mortgage typically shortens it by 4-5 years.

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