What is Mortgage?
A Mortgage Calculator helps you estimate your monthly home loan payment before you start house-hunting. In the United States, the most common mortgage types are the 30-year fixed-rate mortgage and the 15-year fixed-rate mortgage.
As of 2025, the average 30-year fixed mortgage rate hovers around 6.5-7.0%, while 15-year fixed rates are approximately 5.75-6.25%. These are significantly higher than the historic lows of 2.65% seen in early 2021, making it more important than ever to calculate your payments accurately.
A key concept in US mortgages is the 20% down payment threshold. If you put down less than 20%, lenders typically require PMI (Private Mortgage Insurance), which adds $50-200/month to your payment. FHA loans allow as little as 3.5% down, but come with mortgage insurance premiums.
Your monthly payment consists of PITI: Principal, Interest, Taxes, and Insurance. This calculator shows principal and interest — add approximately 1-2% of home value annually for property taxes and $1,000-3,000/year for homeowner's insurance to get your true monthly cost.
Mortgage interest is tax-deductible if you itemize (on loan amounts up to $750,000). However, with the higher standard deduction ($31,400 for MFJ), fewer Americans benefit from this deduction than before the 2017 tax reform.
Compare with our US Income Tax Calculator to see your overall financial picture, or check our Compound Interest Calculator for investment alternatives.
Formula
Monthly Payment = P × r × (1 + r)^n / ((1 + r)^n − 1)
Where: - P = Loan amount (Home Price − Down Payment) - r = Monthly interest rate (Annual Rate / 12 / 100) - n = Total number of months
Worked Example — $400,000 home, 20% down, 6.5%, 30 years: Loan = $400,000 × 0.80 = $320,000 r = 6.5/12/100 = 0.005417 n = 360 months Monthly Payment = $2,023 Total Interest = $408,281 Total Paid = $728,281
15-year vs 30-year comparison ($320,000 at 6.5% vs 6.0%): - 30-year: $2,023/month, $408K total interest - 15-year: $2,701/month, $166K total interest - Savings with 15-year: $242K in interest (pay $678 more/month)
Monthly payment by home price (20% down, 6.5%, 30yr): - $300K home → $1,517/month - $400K home → $2,023/month - $500K home → $2,528/month - $750K home → $3,793/month - $1M home → $5,057/month
How to use this US Mortgage Calculator?
1. Enter Home Price: The full purchase price of the home.
2. Down Payment: Enter as percentage. 20% avoids PMI. FHA minimum is 3.5%. VA and USDA loans allow 0% down for eligible buyers.
3. Interest Rate: Check current rates at Freddie Mac, Bankrate, or your lender. Rates vary by credit score, loan type, and down payment.
4. Loan Term: 360 months (30 years) or 180 months (15 years) are most common.
5. Read Results: Monthly payment shown is principal + interest only. Add ~$300-800/month for property taxes, insurance, and PMI (if applicable) for total housing cost.
The 28/36 Rule: Your mortgage payment should not exceed 28% of gross monthly income, and total debt payments should not exceed 36%.