Mortgage Calculator
Estimate your monthly mortgage payment (principal + interest).
What Is a Mortgage Calculator?
A mortgage calculator estimates the monthly payment on a home loan based on the amount you borrow, the interest rate, and the length of the loan. For most buyers, the mortgage payment is the single largest expense in the household budget, and small differences in rate or term can change that payment by hundreds of dollars a month — and by tens of thousands of dollars in interest over the life of the loan. Running the numbers before you shop for a home turns a vague price range into a concrete monthly figure you can plan around.
This calculator focuses on principal and interest, which make up the core of every mortgage payment. The amount you finance is the home price minus your down payment, and the calculator spreads that balance evenly across the term you choose, adding interest at the rate you enter. Because payments are calculated the same way lenders calculate them, the result gives you a realistic estimate to compare against your budget and against other loan offers.
How to Use the Mortgage Calculator
- Enter the home price — the purchase price of the property you are considering.
- Enter your down payment in dollars. A larger down payment means a smaller loan and a lower payment.
- Enter the annual interest rate your lender is quoting, and choose the loan term in years (30 and 15 are the most common).
- Click Calculate to see your estimated monthly principal-and-interest payment, then try different rates and terms to compare scenarios.
The Formula Behind the Payment
Lenders use a standard amortization formula: M = P × r(1 + r)^n ÷ ((1 + r)^n − 1), where P is the loan amount, r is the monthly interest rate (the annual rate divided by 12), and n is the total number of monthly payments. Early in the loan, most of each payment goes toward interest; over time the balance shifts and more goes toward principal. This is why extra payments early in the term can save so much interest — they cut the balance that future interest is charged on.
Tips Before You Borrow
- Budget for more than principal and interest: property taxes, homeowners insurance, and possibly HOA dues or private mortgage insurance (PMI) are usually added on top.
- A 20% down payment typically avoids PMI, which can add 0.5%–1% of the loan amount per year.
- Compare a 15-year term if you can afford it — the payment is higher, but the interest savings are dramatic.
Does this calculator include taxes and insurance?
No. It calculates principal and interest only, because tax and insurance costs vary widely by location and property. Lenders usually collect those costs monthly in an escrow account, so your total payment to the lender will be higher than the figure shown here.
How much house can I afford on my income?
A common guideline is the 28/36 rule: housing costs should stay under about 28% of your gross monthly income, and all debts combined under about 36%. Use the payment from this calculator to test a home price against your own income and debts.
Why does the interest rate matter so much?
On a $300,000, 30-year loan, a 1% higher rate adds roughly $180 a month — more than $60,000 in extra interest over the full term. That is why comparing quotes from several lenders, and improving your credit score before applying, can pay off so well.
Is my information stored when I use this tool?
No. The calculation runs entirely in your browser. The numbers you enter are never sent to a server, saved, or shared.