What Is the Mortgage Calculator?
A mortgage calculator shows what a home loan really costs month to month and over its full life. By entering the loan amount, interest rate, and term, you instantly see your principal-and-interest payment, the total interest you will pay, and how your balance declines year by year. It's the first number most buyers should check before they start shopping or compare loan offers.
How to use this calculator
Type your numbers into the fields above. The results change the moment you edit any input, so you can try one scenario after another and see exactly what moves. Most calculators show a short summary of the key figures, a line-by-line breakdown underneath, and — where it applies — a year-by-year schedule you can export to a spreadsheet. Everything runs in your browser; nothing is stored or sent anywhere. Treat the output as a planning estimate, not as final word on a real decision.
The Formula
The fixed monthly payment uses the standard 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 ÷ 12 ÷ 100), and n is the number of monthly payments (years × 12). Property tax and insurance are added on top to produce the full PITI payment. Each monthly payment splits between interest (calculated on the remaining balance) and principal; early payments are mostly interest, while later payments build equity faster.
Worked Example
Suppose you borrow $350,000 at 6.5% for 30 years. The calculator returns a principal-and-interest payment of about $2,212 per month. Add $300 in property tax and $120 in insurance and your total housing payment is roughly $2,632. Over 30 years you repay $350,000 of principal plus about $446,000 in interest — a powerful reminder that rate and term choices matter as much as the purchase price.
Tips for the Most Accurate Estimate
- Even a 0.25% lower rate can save tens of thousands in interest over 30 years — always compare quotes.
- Shortening the term to 15 years raises the payment but can cut total interest roughly in half.
- Add realistic tax and insurance so your PITI estimate matches what lenders will actually qualify you for.
- If your down payment is under 20%, budget for private mortgage insurance (PMI) on top of these numbers.
- Use the amortization schedule to see when your loan balance crosses key equity milestones.
Frequently Asked Questions
Q: Does the calculator include PMI?
No. Private mortgage insurance applies when your down payment is below 20% and is not part of the standard PITI estimate. Add it manually if it applies to you.
Q: Why does my early payment barely reduce the balance?
In the first years most of each payment covers interest on the large outstanding balance. As the balance falls, a growing share goes to principal — that is how amortization works.
Q: Should I use a 15- or 30-year term?
A 30-year term keeps payments lower and improves cash flow, while a 15-year term saves large interest but costs more each month. Choose based on your budget and investment alternatives.