Loan & Mortgage Repayment Calculator — Monthly Payment & Amortization

Calculate your monthly repayments, total interest paid, and view a full amortization schedule. Private by design—everything runs locally in your browser.

Inputs

Enter a positive number of years or months.

Results

Enter your loan details and click Calculate. Results will appear here.

Understanding Loan & Mortgage Repayments

A loan or mortgage repayment calculator helps you understand the financial commitments involved in borrowing money. It estimates your monthly payments, the total interest you'll pay over the loan's lifetime, and provides a detailed breakdown of each payment through an amortization schedule.

Key Inputs Explained

  • Loan Amount: The principal sum of money you are borrowing.
  • Annual Interest Rate (% APR): The annual percentage rate charged on the loan principal.
  • Loan Term: The duration over which you will repay the loan.
  • Currency: Select your preferred display currency. The math works the same for any currency.

Key Outputs Explained

  • Monthly Repayment: The fixed amount you'll pay each month (principal + interest).
  • Total Interest Paid: The cumulative interest paid over the loan term.
  • Total Amount Paid: The sum of the loan amount plus all interest paid.
  • Amortization Schedule: A breakdown of each monthly payment into principal and interest.

How This Tool Works

This calculator uses the standard fixed-rate loan amortization formula:

\(M = P \times \frac{i(1+i)^n}{(1+i)^n - 1}\)

  • \(P\) = Loan principal
  • \(i\) = Monthly interest rate (annual rate / 12 / 100)
  • \(n\) = Total number of monthly payments

All calculations are performed client-side in your browser for complete privacy.

5 Fun Facts about Mortgage Repayments

Early years are mostly interest

On a 30-year fixed, month one is often 70%+ interest; by mid-term, the principal share finally overtakes interest.

Front-loaded

One extra yearly is a time warp

Making one extra full payment per year can cut ~4–5 years off many mortgages and save tens of thousands in interest.

Prepay power

Biweekly ≈ 13 payments

26 half-payments a year equals 13 full payments—an automatic prepayment that accelerates payoff without changing the rate.

Timing hack

APR vs effective cost

Quoted APR is simple; interest accrues daily between payments. Effective cost is higher due to compounding.

Real cost

Refi break-even is quick math

Divide refi costs by monthly savings to get break-even months—an easy sanity check before refinancing.

Refi check

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