Your monthly payment depends on three things: the interest rate, the loan term, and how much you put down
A $400,000 mortgage does not have one monthly payment. The same loan amount costs $1,910 per month at 3% interest over 30 years, but $2,280 per month at 6% interest over the same period. If you shorten the loan to 15 years at 6%, the payment jumps to $2,998. The difference between these scenarios is nearly $1,100 a month—or $13,200 a year.
The three variables that move your payment are the interest rate (what the lender charges you to borrow), the loan term (how many years you have to pay it back), and the down payment (how much of the home price you cover upfront). If you are shopping for a mortgage or trying to understand an offer you already have, you need to know all three numbers to calculate what you will actually pay.
Key Takeaways
- A $400,000 mortgage at 6% interest over 30 years costs about $2,280 per month in principal and interest alone.
- Interest rates vary by lender, credit score, and market conditions, so comparing offers from multiple lenders can save you hundreds of dollars per month.
- Your actual monthly housing cost includes property taxes, homeowners insurance, and possibly mortgage insurance—often adding $400 to $800 or more to the principal and interest payment.
- Putting down 20% or more avoids mortgage insurance, which can add $200 to $400 monthly to a $400,000 loan.
- A 15-year loan costs significantly more per month but saves you tens of thousands in total interest over the life of the loan.
How the interest rate changes your monthly payment
Interest rates are the single biggest lever on your monthly cost. The rate you receive depends on market conditions, your credit score, the size of your down payment, and the lender you choose. Even a difference of 0.5% can mean $100 to $150 more or less per month on a $400,000 loan.
Here is what the same $400,000 loan looks like over 30 years at different rates, assuming no down payment (so you are borrowing the full amount):
| Interest Rate | Monthly Payment (Principal + Interest) | Total Interest Paid Over 30 Years |
|---|---|---|
| 3% | $1,910 | $287,600 |
| 4% | $1,910 | $287,600 |
| 5% | $2,147 | $373,000 |
| 6% | $2,399 | $463,600 |
| 7% | $2,661 | $557,800 |
The difference between a 3% rate and a 7% rate is $751 per month. Over 30 years, that adds up to $270,200 in extra interest. This is why shopping around with multiple lenders matters—you may find a rate that is 0.25% or 0.5% lower than the first offer you receive, and that difference compounds over decades.
How the loan term affects what you pay each month and in total
A shorter loan term means higher monthly payments but far less interest paid overall. A 15-year mortgage on $400,000 at 6% costs $2,998 per month—$718 more than a 30-year loan at the same rate. But over the life of the loan, you pay only $139,600 in interest instead of $463,600. You save $324,000 by paying more each month.
The trade-off is cash flow. If you cannot afford the higher monthly payment, a 30-year loan keeps your payment manageable. If you can absorb the higher payment and want to build equity faster and pay less interest, a 15-year loan does both. Some borrowers split the difference with a 20-year loan, which falls between these two in both monthly cost and total interest.
What happens if you put money down
Your down payment reduces the amount you need to borrow. If you put down $80,000 (20% of a $400,000 home price), you borrow $320,000 instead. At 6% over 30 years, that loan costs $1,919 per month instead of $2,399—a savings of $480 per month.
Down payments also affect whether you pay mortgage insurance. If you put down less than 20%, most lenders require you to carry private mortgage insurance (PMI), which protects the lender if you default. PMI typically costs 0.5% to 1% of the loan amount per year, paid monthly. On a $400,000 loan with 10% down ($40,000), you would borrow $360,000 and pay roughly $150 to $300 per month in PMI on top of your principal and interest payment. That insurance drops off once you reach 20% equity in the home, either through payments or appreciation.
Your full monthly housing cost includes more than just the mortgage
The principal and interest payment is only part of what you pay each month. Your actual housing cost also includes property taxes, homeowners insurance, and possibly mortgage insurance. These are often bundled into a single payment called PITI (principal, interest, taxes, insurance).
Property taxes vary dramatically by location—from less than 0.5% of home value per year in some states to over 2% in others. On a $400,000 home, that could be $2,000 per year ($167 per month) or $8,000 per year ($667 per month). Homeowners insurance typically runs $1,000 to $2,000 per year depending on the home and location. Together, taxes and insurance can add $300 to $800 or more to your monthly payment. If you have PMI, add another $150 to $400. Your actual monthly housing cost could be $3,000 to $3,600 or higher, even if your principal and interest payment is $2,400.
How to estimate your payment for a specific scenario
To calculate your own payment, you need four numbers: the loan amount (home price minus down payment), the interest rate, the loan term in years, and the property tax and insurance estimates for your area.
Most lenders and real estate websites have mortgage calculators where you enter these numbers and get an when ready monthly payment. The calculator will show you principal and interest; you then add your local property tax and insurance estimates to get your true monthly cost. If you are considering PMI, the calculator usually has a checkbox to include it.
When you receive a loan offer from a lender, it will include the interest rate, the loan term, and an estimate of taxes and insurance based on the property. Use those numbers in a calculator to verify the monthly payment the lender quoted. If the numbers do not match, ask the lender to explain the difference—sometimes they have included fees or other costs in the payment estimate.
What changes your rate and what does not
Your interest rate is set by the lender based on market conditions and your financial profile. Factors that typically lower your rate: a higher credit score, a larger down payment, a shorter loan term, and a lower loan-to-value ratio (the amount you borrow compared to the home's value). Factors that typically raise your rate: a lower credit score, a smaller down payment, a longer loan term, and a higher loan-to-value ratio.
Rates also move with broader market conditions. When the Federal Reserve raises interest rates, mortgage rates usually rise within weeks. When the Fed cuts rates, mortgage rates typically fall. You cannot control the market, but you can control your credit score and down payment, both of which directly affect the rate you are offered.
Frequently Asked Questions
What is the monthly payment on a $400,000 mortgage at today's rates?
Rates change daily and vary by lender. As of early 2024, rates range from about 6% to 7% for a 30-year fixed mortgage. At 6%, the payment is roughly $2,399 per month (principal and interest only). At 7%, it is roughly $2,661. Check current rates from multiple lenders to see what you would actually be offered based on your credit and down payment.
Does the monthly payment include property taxes and insurance?
No. The principal and interest payment is separate from taxes and insurance. Your lender may collect taxes and insurance each month and hold them in an escrow account to pay them when they are due, but those are additional costs on top of the mortgage payment itself. Ask your lender for an estimate of your total monthly payment including all costs.
Can I lower my monthly payment after I get the mortgage?
You can refinance to a lower rate if rates drop, which lowers your payment. You can also make extra payments toward principal, which shortens the loan term and reduces total interest, though it does not lower the required monthly payment. Some lenders allow you to temporarily reduce your payment if you hit financial hardship, but this extends your loan term and increases total interest.
What if I want to pay off the mortgage faster?
You can make extra payments toward principal at any time without penalty on most mortgages. Paying an extra $200 or $300 per month can cut years off a 30-year loan and save tens of thousands in interest. Some borrowers choose a 15-year loan from the start if they can afford the higher monthly payment; others start with a 30-year loan and make extra payments when cash flow allows.
How much house can I afford if my monthly payment is $2,400?
That depends on your interest rate and down payment. At 6% over 30 years with no down payment, a $2,400 payment covers a $400,000 loan. With 20% down, that same payment covers a $500,000 home. Lenders also consider your total debt and income—most want your housing payment to be no more than 28% of your gross monthly income. If you earn $8,500 per month, a $2,400 payment is near the top of what they will lend.