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Loan Amortization Calculator

Enter loan amount, annual rate and term to compute the fixed monthly payment, total interest and total repayment.

Input Data

Loan Amount
Annual Rate
%
Years
yr

Results

Fixed monthly payment.
5,006
Total interest over the term.
501,871
Total of all payments.
1,501,871

At a glance:Monthly rate i = annual ÷ 12; periods n = years × 12. Monthly payment = P × i × (1+i)^n ÷ ((1+i)^n − 1) (at i=0, P÷n). Total repayment = monthly × n; total interest = total repayment − P.

Formula

i = annual ÷ 12; n = years × 12.

Monthly = P × i(1+i)^n ÷ ((1+i)^n − 1).

Total interest = monthly × n − P.

How to Use

  1. Enter the loan principal.
  2. Enter the annual rate and term.
  3. View monthly payment, total interest and total repayment.

Case Studies

1,000,000 at 3.5% over 25 years

i = 0.035/12 = 0.0029167; n = 300.

Monthly ≈ 1,000,000 × 0.0029167×1.0029167^300 / (1.0029167^300−1) ≈ 5,010.

Total repayment ≈ 1,503,000; total interest ≈ 503,000.

FAQ

Why is the total interest so high?

Over a long term interest accumulates heavily. Borrowing 1m for 25 years, interest can approach half the principal. Shortening the term cuts interest a lot.

Is more paid in interest early on?

Yes. Early payments are mostly interest, later mostly principal. This tool gives totals; a full schedule needs the amortisation table (not included).

How does this differ from the affordability calculator?

Affordability asks 'how much can I borrow' (from a max payment); this asks 'having borrowed, what is the monthly and total interest' (from principal). Opposite directions.

Fixed or floating rate?

This tool assumes a fixed rate throughout. HK mortgages are often H-Plan/P-Plan floating, so the payment moves with the prime rate; assess with a stress-test rate (e.g. +2%).

Is early repayment worth it?

Usually yes, as it saves future interest, but some loans have penalty periods or fees — compare the fee against interest saved. This tool excludes penalties.

Does i=0 (interest-free) error?

No. At i=0 the formula's denominator is zero; this tool special-cases it to principal ÷ periods.

Related Tools

References

Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.

Found a problem with the results?

If this calculator's result is wrong, or you have any question about the calculation logic, please let us know. You are viewing:Loan Amortization Calculator（/finance/loan-amortization）。