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Mortgage Calculator

Estimate your monthly mortgage payment, total interest, and full amortization schedule instantly in your browser — no signup, no data leaves your device.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Enter the home price and your down payment — the calculator subtracts the down payment to get the loan principal.
  2. 2.Type your annual interest rate and pick a loan term (15 or 30 years, or enter a custom number of years).
  3. 3.Read your monthly payment, total interest, and total paid instantly, then expand the amortization schedule or add property tax, insurance, and HOA to see your full PITI monthly total.

About Mortgage Calculator

The Mortgage Calculator turns four numbers — home price, down payment, annual interest rate, and loan term — into the figures that actually decide whether a house fits your budget: your fixed monthly payment, the total interest you will pay over the life of the loan, and a year-by-year breakdown of how each payment splits between principal and interest. Everything runs locally in your browser, so your financial inputs are never uploaded or stored.

Methodology: this tool uses the standard fixed-rate amortization (annuity) formula. It first converts your annual interest rate into a monthly rate r = (annual rate % / 100) / 12 and your term into a number of monthly payments n = years * 12. The fixed monthly principal-and-interest payment M is then M = P * r * (1 + r)^n / ((1 + r)^n - 1), where P is the loan principal (home price minus down payment). When the interest rate is exactly 0%, the formula collapses to M = P / n, an equal split of the principal across every month. The amortization schedule is built by applying interest to the outstanding balance each month, subtracting that interest from the fixed payment to find the principal portion, and reducing the balance until it reaches zero at the final payment. Two assumptions matter: the rate is fixed for the whole term, and interest compounds monthly. These are the standard conventions for U.S. fixed-rate mortgages.

P&I versus PITI: the headline monthly figure is P&I — principal and interest only, the amount that repays the loan itself. Real housing costs are usually larger. When you add the optional property tax rate, annual homeowners insurance, and monthly HOA dues, the tool also shows an estimated monthly total, commonly called PITI (Principal, Interest, Taxes, and Insurance) plus HOA. Property tax is estimated as home value * tax rate / 12, insurance as the annual premium / 12, and HOA is added as-is. These add-ons do not change how fast your loan is paid off; they simply raise the cash you send each month, which is why lenders qualify you on PITI rather than P&I alone.

This calculator is provided for general information and planning only. It does not account for private mortgage insurance (PMI), points, closing costs, adjustable rates, extra payments, or escrow adjustments, and it is not financial advice. Always confirm exact figures with a licensed lender or mortgage professional before making any decision.

Methodology & sources

This calculator uses the standard fixed-rate mortgage amortization formula: M = P·r(1+r)^n / ((1+r)^n − 1), where P is the loan principal, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments (years × 12). When the interest rate is 0%, the monthly payment reduces to P ÷ n. Total interest equals the sum of all payments minus the principal.

All figures are estimates for general information only and are not financial advice. Verify exact terms with a licensed lender.

Frequently asked questions

How is my monthly mortgage payment calculated?
It uses the standard fixed-rate amortization formula. The monthly rate is r = (annual rate / 100) / 12 and the number of payments is n = years * 12. The fixed monthly principal-and-interest payment is M = P * r * (1 + r)^n / ((1 + r)^n - 1), where P is the loan principal. At a 0% rate it simplifies to M = P / n.
What is the difference between P&I and PITI?
P&I is Principal and Interest — the amount that repays the loan itself, and the headline figure this tool shows by default. PITI adds Taxes and Insurance (property tax and homeowners insurance) to that base; with HOA dues included, it reflects your true total monthly housing cost, which is what lenders use to qualify you.
Is this mortgage estimate financial advice?
No — it is an estimate for general information and planning only. It excludes PMI, points, closing costs, adjustable rates, and escrow changes. Always verify exact figures with a licensed lender or mortgage professional before making a decision.

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