Financial

Free Amortization Calculator

Year-by-year principal, interest, and remaining balance schedule.

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Inputs

$
%

Result

Monthly payment

$1,580.17

End of year 1Bal $247,205.69
End of year 5Bal $234,027.44
End of year 10Bal $211,940.32
End of year 15Bal $181,397.85
End of year 30Bal $0.00
Total interest$318,861.22
Total paid$568,861.22

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Short answer

Each payment covers this period's interest first (balance × monthly rate) and applies the remainder to principal. Early payments are mostly interest; late payments are mostly principal.

What is the Amortization Calculator?

The month-by-month decomposition of every loan payment into interest and principal, plus the remaining balance.

How does the Amortization Calculator work?

Multiply the current balance by the monthly rate for this month's interest. Subtract from the payment to get principal. Subtract principal from balance. Repeat.

Formula

interest_k = balance_{k-1} · r; principal_k = PMT − interest_k; balance_k = balance_{k-1} − principal_k

Variables

  • rMonthly rate
  • PMTFixed monthly payment

Explanation

Iterating this recurrence for every period generates the full amortization schedule.

Examples

Example 1: $250k, 6.5%, 30 yr

First payment: $1,354 interest / $226 principal. Year 15: about half principal, half interest.

Applications

  • Understanding mortgage payoff dynamics
  • Refi break-even math
  • Extra-payment strategy planning

Advantages

  • Reveals early-year interest concentration
  • Enables informed refinance and prepayment decisions

Limitations

  • Assumes fixed rate — ARMs need per-period rate resets

Common mistakes

  • Assuming payments are 50/50 interest/principal from day one

Tips

  • Every dollar of early principal saves years of future interest

Related concepts

The Amortization Calculator sits inside the Finance Calculators hub, in the loans & debt payoff cluster. Instalment borrowing, credit cards and payoff strategy. Understanding the terms below makes the output easier to interpret and easier to compare against neighbouring measures.

principalAPRtermavalanche methodsnowball methodminimum payment

Practical use cases and industry applications

Understanding Amortization

The month-by-month decomposition of every loan payment into interest and principal, plus the remaining balance. Within finance calculators, amortization belongs to the loans & debt payoff cluster, where it shares terminology and assumptions with closely related tools.

Learning how amortization is calculated

Iterating this recurrence for every period generates the full amortization schedule. Working through the variables one at a time — r, PMT — makes the result reproducible by hand and easier to sanity-check.

Using amortization to make a decision

Understanding mortgage payoff dynamics Refi break-even math Extra-payment strategy planning Because outputs depend on the assumptions you enter, run more than one scenario before committing to a figure.

How amortization compares with related measures

principal, APR, term, avalanche method all describe adjacent aspects of loans & debt payoff. Comparing this calculator's output against those measures — using the related tools listed on this page — prevents a single metric from being read in isolation.

Frequently asked questions

Why is my early payment mostly interest?

Because interest is charged on the full remaining balance, which is largest in year one.

Related calculators

More loans & debt payoff tools

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