Mortgage Payment Calculator — What Will This House Really Cost You?

A mortgage calculator helps you estimate your monthly home loan payment before you ever speak to a lender. Enter your home price, down payment, interest rate, and loan term to instantly see your principal-and-interest payment, total interest paid over the life of the loan, and total cost of the home. Use it to compare 15-year vs 30-year loans, test different down payment amounts, or see how much house your budget supports.

How to use this Mortgage Calculator

1. 1Enter the home price — the full purchase price before your down payment.
2. 2Enter your down payment as a dollar amount or percentage. Most conventional loans require at least 3–20%.
3. 3Enter the annual interest rate. Check current rates at your bank, credit union, and online lenders — even 0.25% matters over 30 years.
4. 4Select the loan term: 30 years is the most common; 15 years costs less total interest but has a higher monthly payment.
5. 5The calculator shows your monthly principal-and-interest payment, total interest paid, and total amount paid over the loan life.

Monthly mortgage payment formula explained

Your monthly mortgage payment is calculated using the standard amortization formula. It ensures the loan is fully paid off — with interest — by the end of the term, with equal payments every month.

Home loan calculator example: $400,000 home with 20% down

1. 01Home price: $400,000. Down payment: $80,000 (20%). Loan amount: $320,000.
2. 02Interest rate: 7.0% annual → monthly rate r = 0.07 ÷ 12 = 0.005833.
3. 03Loan term: 30 years → n = 30 × 12 = 360 payments.
4. 04Monthly payment = $320,000 × [0.005833 × (1.005833)^360] / [(1.005833)^360 − 1]
5. 05Monthly payment = $320,000 × [0.005833 × 10.936] / [10.936 − 1] = $2,129

What affects your monthly mortgage payment?

Tips and things to know

• ✓Get rate quotes from at least 3 lenders — banks, credit unions, and online lenders — before accepting any offer.
• ✓A 15-year mortgage at the same rate as a 30-year roughly doubles your monthly payment but cuts total interest by more than half.
• ✓Making one extra mortgage payment per year reduces a 30-year loan by 4–5 years.
• ✓If you put down less than 20%, add PMI costs (0.5–1.5% of loan amount per year) to get your true monthly housing cost.
• ✓This calculator shows principal and interest only. Budget an additional $300–$700/month for taxes, insurance, and maintenance.

Mortgage Calculator — bottom line

The single most important step before house shopping is stress-testing the payment you calculate here against your actual monthly take-home pay — not your gross income. Lenders qualify you on gross income (the standard is 28% for housing costs and 36% for all debt). But you live on take-home pay, which is typically 25–35% less after taxes and benefits. A payment that looks manageable on paper can become a serious cash-flow problem when it lands on a real bank statement. The most common mistake is treating a lender's pre-approval limit as a shopping budget. Pre-approval tells you the maximum the lender will extend — not the maximum you can comfortably afford. A practical guideline: your total housing cost (principal, interest, taxes, insurance, and HOA) should stay below 25–28% of your take-home pay, not your gross salary. Use this calculator to test your target home price, then subtract 10% to find your comfortable ceiling. The second most costly mistake is accepting the first rate offer. On a $350,000 loan at 30 years, the spread between 6.75% and 7.25% costs roughly $110 per month — $39,600 over the loan life. Shop at least three lenders before accepting any rate. Before you move to the offer stage, run three scenarios in this calculator: your target price, a price 10% lower, and a price 10% higher. Identify the down payment level that eliminates PMI (typically 20%). Confirm that the 15-year payment is within reach — if it is, the interest savings are substantial. Then check the Home Affordability Calculator to validate that your income supports the range you're targeting.

Official resources and further reading