Mortgage Calculator

What Is a Mortgage Calculator?

A mortgage calculator is a free online tool that turns four numbers — the home price, your down payment, the interest rate and the loan term — into a monthly payment you can plan around. A mortgage itself is a loan secured by the property you are buying: you borrow most of the purchase price, repay it in equal monthly installments, and the lender holds a claim on the house until the balance reaches zero. Use this mortgage payment calculator before you start house hunting, while you compare lenders, or any time you want to see how a different rate or down payment changes what you owe each month.

How Your Monthly Mortgage Payment Is Calculated

M = P × [r(1 + r)ⁿ] ÷ [(1 + r)ⁿ − 1] is the standard fixed-rate formula. P is the amount you borrow (home price minus down payment), r is the monthly rate (the annual rate divided by 12), and n is the number of monthly payments (years × 12). The payment stays flat for the whole term, but what it is made of keeps shifting: early payments are mostly interest, and later ones are mostly principal. That is why a loan feels like it barely moves in its first few years.

The Costs Hiding Outside the Payment

The figure above covers principal and interest only. Owning a home adds recurring costs that are easy to forget when you are comparing monthly numbers:

• Property taxes — set by your local government, usually a percentage of assessed value, and often paid monthly through an escrow account.
• Homeowners insurance — required by nearly every lender; the price depends on location, rebuild cost and coverage.
• Private mortgage insurance (PMI) — typically charged on conventional loans when the down payment is under 20%.
• HOA fees — monthly or yearly dues in condos and planned communities.
• Maintenance and repairs — a common planning rule is to set aside roughly 1% of the home's value per year.
• Closing costs — a one-time bill at purchase, often 2%–5% of the loan, covering appraisal, title, lender and legal fees.

Add these on top of the calculator's result to get a realistic monthly budget. Lenders look at the combined figure when they decide how much you can borrow.

How Much Home Can You Afford?

A widely used guideline is the 28/36 rule: keep housing costs at or below 28% of your gross monthly income, and total debt payments (housing plus car loans, cards and so on) at or below 36%. It is only a starting point — your savings, job stability and other goals matter too — but it is a useful check against a payment that looks fine today and feels heavy in a year.

Ways to Pay Off a Mortgage Faster

• Make extra principal payments. Every extra dollar goes straight to the balance, which shrinks the interest charged on all later months.
• Pay biweekly. Half a payment every two weeks adds up to 26 half-payments, or 13 full payments, per year instead of 12.
• Refinance to a shorter term or lower rate when market rates make it worthwhile — weigh the closing costs against the savings.
• Round the payment up. Paying a flat, slightly higher amount is painless and compounds in your favor.

Check whether your loan charges a prepayment penalty before sending extra money, and compare the guaranteed return of paying down debt with what you could earn elsewhere.

Fixed-Rate vs. Adjustable-Rate Mortgages

This calculator assumes a fixed rate, where the rate and the payment never change. An adjustable-rate mortgage (ARM) starts with a lower introductory rate for a set period and then resets periodically with the market, so the payment can rise or fall. ARMs can suit buyers who expect to sell or refinance before the first reset; fixed rates suit anyone who values a predictable bill. For a loan that is not a home purchase, try the Loan Calculator, and to see a payment broken down month by month, open the Amortization Calculator.