What is a mortgage calculator?
A mortgage calculator computes your monthly payment — the EMI, or Equated Monthly Installment — using the standard amortization formula, then breaks every dollar down into principal and interest across the full life of the loan. This version also folds in property tax, homeowner's insurance and optional extra payments so you see the true total cost of homeownership instead of just the headline payment. Everything runs entirely in your browser, so none of your numbers are ever sent to a server.
The formula behind the payment
The monthly payment is calculated as M = P · r · (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1), where P is the loan amount (home price minus down payment), r is the monthly interest rate (the annual rate divided by twelve, then by one hundred), and n is the total number of monthly payments. For a $350,000 loan at 6.75% over 30 years, the monthly rate is 0.005625 and there are 360 payments, producing a base EMI of about $2,270. If the rate is zero, the payment is simply the loan divided by the number of months.
How to use it, step by step
Enter the home price and, optionally, a down payment — the loan amount is the difference between the two. Add the annual interest rate as a percentage (for example, 6.75 for 6.75% APR), then set the loan term in years; 15 and 30 are the most common. Use the extra-payment field to model overpaying each month, and enter estimated annual property tax and insurance for a realistic all-in figure. The summary cards, the result line and the amortization schedule all update instantly as you type.
Understanding your results
The base EMI is the core principal-and-interest payment your lender receives each month. The total monthly payment adds estimated tax and insurance to show your true monthly housing cost. Total interest paid is striking on a long loan — over 30 years at typical rates you can pay nearly as much in interest as you borrowed. The amortization schedule reveals why: in the early years most of each payment is interest, and only over time does the balance tip toward principal.
The power of extra payments
Because every extra dollar goes straight to principal, even modest overpayments compound into large savings. Adding $200 a month to a $350,000 / 30-year / 6.75% mortgage can save well over $80,000 in interest and retire the loan roughly six years early. Use the extra-payment field to model your own scenarios — the results are usually larger than people expect, because cutting the balance early removes interest from every month that follows.
Export and reuse your schedule
The on-screen schedule shows the first twelve months, annual snapshots and the final payment so you can see the principal-versus-interest shift at a glance. For the complete month-by-month breakdown, use the CSV export to download every row and open it in a spreadsheet for budgeting, refinancing comparisons or tax planning. You can also copy the summary numbers in one click. All processing is local to your device, so your financial details never leave your browser.