How to Use This Calculator
Enter the home price, your down payment, the interest rate, and loan term. The calculator shows your monthly payment broken down into principal, interest, taxes, insurance, and PMI — plus a full amortization schedule showing exactly how your loan gets paid off over time.
The most revealing thing to try? Compare a 15-year mortgage to a 30-year mortgage. The monthly payment is higher, but the total interest savings are often shocking — tens of thousands of dollars.
Here's what each field means:
Home Price is the purchase price of the property. This is the total amount, before your down payment is applied.
Down Payment is the cash you pay upfront. The loan covers the rest. Putting down 20% eliminates PMI and gives you better loan terms. But many people buy with as little as 3-5% down [1].
Loan Term is how many years you'll take to repay the mortgage. The most common options are 30 years (lower monthly payments, more total interest) and 15 years (higher payments, much less interest).
Interest Rate is the annual rate your lender charges. Even small differences matter enormously over 30 years. A 0.5% rate reduction on a $300,000 loan saves roughly $30,000 in total interest.
Property Tax Rate is your local government's annual tax on the property, usually expressed as a percentage of assessed value. Rates vary wildly — from under 0.5% in some states to over 2% in others [2]. This gets added to your monthly payment.
Homeowners Insurance is the annual premium to insure your home against damage, theft, and liability. It's required by your lender and typically costs $1,000-$3,000 per year depending on location and home value.
HOA Fees are monthly fees charged by your homeowners association (if applicable) for shared amenities and maintenance. Not all properties have HOAs, but condos and planned communities almost always do.
PMI (Private Mortgage Insurance) is required if your down payment is less than 20%. It protects the lender (not you) if you default. PMI typically costs 0.5-1% of the loan amount annually and drops off once you reach 20% equity [3].
How a Mortgage Actually Works
A mortgage is a loan secured by your home. You borrow money from a bank, use it to buy the house, and pay the bank back over time with interest. If you stop making payments, the bank can take the house through foreclosure.
Every month, you make one payment, but it actually covers several things: a portion goes toward paying down the loan (principal), a portion goes toward the bank's fee for lending you the money (interest), and additional amounts cover property taxes and insurance (held in an escrow account).
Here's the part most people don't realize until they see the amortization schedule: in the early years of a 30-year mortgage, most of your payment goes toward interest, not principal. On a $300,000 loan at 6.5%, your first monthly payment of $1,896 breaks down like this:
- Interest: $1,625 (86% of your payment)
- Principal: $271 (14% of your payment)
That ratio gradually shifts over time. By year 15, the split is roughly even. By year 25, most of your payment goes toward principal. This front-loading of interest is why paying extra toward principal in the early years has such a powerful effect on total interest saved.
Fixed Rate vs. Adjustable Rate Mortgages
Fixed-rate mortgages lock in your interest rate for the entire loan. Your payment never changes (though taxes and insurance may). This is the right choice for most people, especially if you plan to stay in the home long-term. About 90% of mortgages are fixed-rate [4].
Adjustable-rate mortgages (ARMs) start with a lower introductory rate for a set period (typically 5, 7, or 10 years), then adjust periodically based on market rates. A "5/1 ARM" means the rate is fixed for 5 years, then adjusts every year after that.
ARMs make sense in specific situations: you're confident you'll sell or refinance within the fixed period, or you believe rates will drop. But if rates rise, your payment can increase substantially — sometimes by hundreds of dollars per month.
15-Year vs. 30-Year: The Great Debate
On a $300,000 loan at 6.5%:
| 30-Year | 15-Year | |
|---|---|---|
| Monthly Payment | $1,896 | $2,613 |
| Total Interest | $382,633 | $170,389 |
| Total Paid | $682,633 | $470,389 |
The 15-year mortgage costs $717 more per month but saves $212,244 in total interest. That's the price of time.
If you can afford the higher payment, a 15-year mortgage is the better financial deal by a wide margin. If the payment is too tight, a 30-year mortgage with occasional extra principal payments is a solid middle ground.
The True Cost of Your Home
The sticker price is just the beginning. Here's what homeownership actually costs:
Closing costs run 2-5% of the loan amount. On a $300,000 mortgage, that's $6,000-$15,000 in fees for appraisals, title insurance, lender origination, and escrow setup [5].
Maintenance is the cost most new homeowners underestimate. Budget 1% of the home value per year — $3,000-$4,000 for a $350,000 home. Roofs, HVAC systems, plumbing, and appliances all eventually need repair or replacement.
Property taxes are ongoing and can change. Some states reassess property values annually, and rates can increase with local government budgets.
Insurance is required and can spike after natural disasters or claims.
Utilities and HOA fees are monthly costs that don't build equity.
Add it all up and the total cost of owning a $350,000 home over 30 years — including purchase, interest, taxes, insurance, and maintenance — can easily exceed $700,000.
How to Use This Calculator Strategically
Find your comfortable payment. Enter different home prices until you find a monthly payment that fits your budget. Financial advisors recommend keeping your total housing cost (mortgage + taxes + insurance) below 28% of your gross monthly income [6].
Compare down payment scenarios. See how 5%, 10%, and 20% down payments affect your monthly cost and total interest. The PMI savings at 20% are significant.
Test extra payments. If your calculator supports it, add $100 or $200 extra per month toward principal. You'll be surprised how many years it shaves off the loan and how much interest it saves.
Shop rates aggressively. Run the calculator at the lowest rate you've been quoted and the highest. The difference over 30 years is substantial, and it only takes a few hours of comparison shopping.
References
- Consumer Financial Protection Bureau. (2025). Buying a House: How Much Can You Afford?
- Tax Foundation. (2025). Property Taxes by State.
- Consumer Financial Protection Bureau. (2025). What Is Private Mortgage Insurance?
- Freddie Mac. (2025). Primary Mortgage Market Survey Archives.
- Consumer Financial Protection Bureau. (2025). What Are Closing Costs?
- Consumer Financial Protection Bureau. (2025). Debt-to-Income Ratio.
This calculator is for educational purposes only and does not constitute financial advice. Mortgage rates, terms, and costs vary by lender and individual circumstances. Consider consulting a qualified mortgage professional for personalized guidance.