Start with the loan amount, interest rate, and term to find your payment
Your monthly house payment depends on three numbers: how much you borrow, the interest rate you pay on that loan, and how many years you have to pay it back. If you know these three things, you can calculate your payment before you sign anything. The calculation itself is straightforward—lenders use the same formula whether you're buying a $200,000 house or a $2 million one.
The payment covers principal (the money you borrowed) and interest (what the lender charges you for lending it). On a 30-year loan, your early payments are mostly interest; by year 25, most of your payment goes toward principal. Property taxes, homeowners insurance, and mortgage insurance (if your down payment is less than 20 percent) are separate and stack on top of this base payment.
Key Takeaways
- Your base monthly payment depends only on loan amount, interest rate, and loan term—use an online calculator or the standard mortgage formula to find it in seconds.
- Property taxes, homeowners insurance, and mortgage insurance are not part of the base payment and must be added separately to get your true monthly cost.
- A higher down payment lowers both your loan amount and the chance you'll pay mortgage insurance, which can save hundreds per month.
- Interest rates change daily, so get a rate quote from your lender before you calculate—a difference of 0.5 percent can change your payment by $200 or more on a $400,000 loan.
- Your actual payment may include escrow for taxes and insurance, which your lender collects each month and pays on your behalf.
Use the standard mortgage formula or an online calculator
The formula lenders use is: M = P [ r(1 + r)^n ] / [ (1 + r)^n – 1 ], where M is your monthly payment, P is the loan amount, r is your monthly interest rate (annual rate divided by 12), and n is the total number of payments. If you have a calculator that handles exponents, you can work through it by hand. Most people don't—they use an online mortgage calculator instead.
A mortgage calculator asks for three inputs: loan amount, interest rate, and loan term in years. It returns your monthly principal and interest payment in seconds. Bankrate, NerdWallet, and most lender websites have free calculators. They all use the same formula, so the answer is the same no matter which one you use. Enter the numbers and you have your base payment.
The calculator gives you only principal and interest. It does not include property taxes, homeowners insurance, HOA fees, or mortgage insurance. Those are real costs you will pay, but they vary by location and your specific situation, so you have to add them separately.
Add property taxes, insurance, and mortgage insurance to get your true monthly cost
Your lender will require you to pay property taxes and homeowners insurance as part of your monthly mortgage payment. These go into an escrow account—the lender collects the money each month and pays the bills when they come due. You do not write separate checks; the lender handles it.
Property taxes vary wildly by location. A $400,000 house in New Jersey might have $8,000 per year in property taxes ($667 per month), while the same house in Alabama might have $4,000 per year ($333 per month). Check your county assessor's website or ask your real estate agent what the tax rate is in the area you're looking at. Multiply the home price by the local tax rate to estimate your annual tax, then divide by 12.
Homeowners insurance typically costs $800 to $2,000 per year depending on the house, location, and coverage level. Get quotes from at least two insurers before you buy. Divide the annual premium by 12 to get your monthly cost.
If your down payment is less than 20 percent of the home price, your lender will require private mortgage insurance (PMI). This protects the lender if you default, not you. PMI usually costs 0.5 to 1.5 percent of your loan amount per year, depending on your credit score and how much you put down. A $400,000 loan with 10 percent down ($40,000) means you borrowed $360,000. At 1 percent per year, PMI costs $3,600 annually, or $300 per month. Once you reach 20 percent equity in the home, you can request to have PMI removed.
Understand how interest rates move your payment
Interest rates change daily based on market conditions. A difference of 0.5 percent sounds small, but it changes your payment significantly. On a $400,000 loan over 30 years, the difference between 6.5 percent and 7.0 percent is about $210 per month—$2,520 per year.
When you get a rate quote from a lender, ask how long the quote is good for. Most lenders lock your rate for 30 to 60 days while you shop for a house and go through underwriting. If rates rise during that time, your locked rate protects you. If rates fall, you may be able to renegotiate before closing, though some lenders charge a fee to re-lock at a lower rate.
Shop rates from at least three lenders. They all lend the same money at different prices. One lender might quote you 6.8 percent while another quotes 7.1 percent for the same loan. Over 30 years, that 0.3 percent difference costs you tens of thousands of dollars in extra interest.
Account for different loan terms and how they affect your payment
A 30-year mortgage is the most common, but 15-year and 20-year loans exist too. A shorter term means a higher monthly payment but much less interest paid over the life of the loan. On a $400,000 loan at 7 percent interest, a 30-year payment is about $2,661 per month. A 15-year payment on the same loan is about $3,738 per month—$1,077 more each month, but you pay off the house in half the time and pay roughly half the total interest.
Some people choose a 30-year loan but make extra principal payments when they can afford it. This shortens the loan without locking you into a higher monthly payment. If money gets tight, you can go back to the regular payment. With a 15-year loan, you cannot lower the payment if your situation changes.
Adjustable-rate mortgages (ARMs) start with a lower interest rate for a set period (often 3, 5, 7, or 10 years), then adjust annually based on market rates. Your initial payment is lower, but it will rise when the rate adjusts. If you plan to sell or refinance before the rate adjusts, an ARM can save you money. If you plan to stay in the house for 30 years, a fixed-rate loan is simpler to budget for.
Build a complete monthly payment estimate with a worksheet
Use this breakdown to estimate your total monthly housing cost:
| Component | How to Find It | Example |
| Loan amount | Home price minus down payment | $400,000 – $80,000 = $320,000 |
| Interest rate | Get quote from lender | 7.0% |
| Loan term | Choose 15, 20, or 30 years | 30 years |
| Principal & interest | Use mortgage calculator | $2,133 |
| Property tax (monthly) | Annual tax ÷ 12 | $6,000 ÷ 12 = $500 |
| Homeowners insurance (monthly) | Annual premium ÷ 12 | $1,200 ÷ 12 = $100 |
| PMI (if down payment < 20%) | Lender quote or 0.5–1.5% of loan ÷ 12 | $2,400 ÷ 12 = $200 |
| HOA fees (if applicable) | Ask seller or HOA | $150 |
| Total monthly payment | Add all rows above | $3,083 |
This total is what you will pay each month. Lenders typically want your total housing payment (including taxes, insurance, and PMI) to be no more than 28 percent of your gross monthly income. If your household earns $8,000 per month, your housing payment should not exceed $2,240. Use this rule to check whether a house price is realistic for your budget before you start shopping.
Know what changes and what stays the same over time
Your principal and interest payment never changes on a fixed-rate loan—it is the same on month 1 and month 360. Property taxes and insurance can rise, sometimes significantly. Property taxes increase when your local government raises rates or when your home is reassessed. Insurance premiums rise when claims go up in your area or when you add coverage. Budget for 2 to 3 percent annual increases in taxes and insurance, though the actual increase varies by location and year.
PMI drops off automatically once you reach 20 percent equity, or you can request removal earlier if your home has appreciated and you have paid down the loan. Some states allow you to request PMI removal once you hit 20 percent equity; others require you to wait until you reach 22 percent. Check your loan documents or ask your lender.
If you refinance—taking out a new loan to pay off the old one—your principal and interest payment can change, and your new loan term starts over. Refinancing makes sense if rates drop significantly or if you want to shorten your loan term, but it costs money upfront (closing costs), so calculate whether the monthly savings justify the cost.
Frequently Asked Questions
What's the difference between a mortgage payment and total housing cost?
Your mortgage payment is principal and interest only. Total housing cost includes property taxes, homeowners insurance, PMI, and HOA fees. Lenders quote the mortgage payment, but your actual monthly bill is higher. Always add taxes and insurance before deciding whether you can afford a house.
Can I pay off my mortgage faster without refinancing?
Yes. Make extra principal payments whenever you can. Even an extra $100 per month cuts years off a 30-year loan and saves tens of thousands in interest. Ask your lender whether there are prepayment penalties (rare on mortgages, but worth checking). Some lenders allow you to make bi-weekly payments instead of monthly, which also accelerates payoff.
How much should I put down?
Twenty percent avoids PMI, but it is not required. Putting down 10 or 15 percent means you pay PMI, which adds $200 to $400 per month on a typical loan. If you can reach 20 percent, the savings usually justify waiting. If you cannot, a smaller down payment lets you buy sooner—just budget for PMI in your monthly cost.
What if my interest rate is locked but rates drop before closing?
Contact your lender and ask whether you can re-lock at the lower rate. Some lenders allow one free re-lock; others charge a fee (typically $250 to $500). If the rate drop is small, the fee may not be worth it. If rates drop 0.5 percent or more, re-locking usually saves money over the life of the loan.
Does my payment include property taxes and insurance automatically?
Yes, if your lender requires escrow. Most lenders collect taxes and insurance as part of your monthly payment and pay the bills from an escrow account. Some lenders allow you to pay taxes and insurance separately if you have enough equity and a good credit score, but this is uncommon for new loans. Ask your lender what their escrow policy is.