Mortgage Calculator: Estimate Your Monthly Payment & Total Cost

A mortgage calculator shows you exactly what you'll pay each month before you commit to a home loan. You get your principal and interest payment, plus property tax, homeowners insurance, HOA dues and PMI—the full picture in 30 seconds.

A mortgage calculator computes your monthly mortgage payment using four core inputs: home price, down payment, interest rate and loan term. The tool splits your payment into principal (the amount you borrowed), interest (what the lender charges), and escrow items like property tax and insurance.

Run the numbers before you talk to a lender so you know what's realistic.

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The calculator instantly shows your estimated monthly payment and total interest over the life of the loan.

The standard mortgage formula calculates your principal and interest payment:

M = P [ r(1 + r)^n ] / [ (1 + r)^n – 1 ]

• M = monthly payment (principal + interest only)
• P = loan principal (home price minus down payment)
• r = monthly interest rate (annual rate ÷ 12)
• n = number of payments (loan term in years × 12)

Here's what a $350,000 home looks like with different down payments and terms.

The 30-year loan with 20% down saves you $515/month compared to 5% down (thanks to no PMI and a smaller principal). The 15-year loan costs $654 more per month but cuts your total interest from $390,680 to $173,060—a $217,620 saving.

Loan term trades monthly cost for total interest. A 15-year mortgage doubles your principal paydown speed and cuts interest in half, but raises your monthly payment by 40–50%.

Down payment size eliminates PMI at 20% and shrinks your loan balance. Every extra $10,000 down cuts your payment by roughly $67/month at 7% interest.

A mortgage calculator gives you a ballpark estimate using inputs you control. A mortgage pre-approval is a lender's binding offer based on your credit score, income, debts and employment history.

The calculator can't see your 720 FICO, your $8,000/month gross income or your $450 car payment. The lender uses those to compute your debt-to-income ratio (total monthly debts ÷ gross income) and approve a specific loan amount and rate.

Forgetting escrow costs. Your lender collects property tax and insurance monthly, then pays the bills annually. Add $400–$800/month to your principal and interest to see the real payment.

Ignoring PMI. Private mortgage insurance costs 0.5–1.5% of your loan amount per year when you put down less than 20%. On a $300,000 loan that's $125–$375/month until you hit 20% equity.

Skipping HOA fees. Homeowners association dues run $100–$700/month and never go away. They're not part of your mortgage but they're part of your housing budget.

Assuming the rate stays fixed. If you're modeling an adjustable-rate mortgage (ARM), the initial rate resets after 5, 7 or 10 years. Run the calculator at the fully indexed rate (index + margin) to see worst-case payments.

Comparing loan offers. Plug in each lender's rate, term and fees to see which deal costs less over time. A 0.25% rate difference saves $15,000–$20,000 in interest on a $300,000 loan.

Refinance analysis. Calculate your new payment and break-even point (closing costs ÷ monthly savings). If you save $200/month and closing costs are $4,000, you break even in 20 months.

For broader financial planning around your home purchase, explore the tools at [/free-tools](/free-tools) or dive into strategies in our [career and income](/career-and-income) section.

Lenders use the 28/36 rule: your housing payment shouldn't exceed 28% of your gross monthly income, and total debts shouldn't exceed 36%.

Reverse the mortgage calculator: if your max payment is $2,240 and you're looking at 7% interest, 30-year term, with $500/month for tax and insurance, you can afford roughly $1,740 in principal and interest. That supports a loan of about $261,000, or a $326,000 home with 20% down.

A fixed-rate mortgage keeps the same interest rate for 15 or 30 years. Your principal and interest payment never changes (though tax and insurance can go up).

Run both scenarios in the calculator. If the ARM saves you $150/month for seven years ($12,600 total) but could jump $400/month afterward, decide whether you'll sell, refinance or pay it off before the reset.

The calculator asks for an interest rate but doesn't check your credit. In reality, your FICO score determines your rate: 760+ gets the best pricing, 680–759 pays 0.25–0.5% more, and below 640 adds 1–2% or requires FHA/VA loans.

What is a mortgage calculator used for?

A mortgage calculator estimates your monthly home loan payment by combining principal, interest, property tax, homeowners insurance and PMI. You input the home price, down payment, interest rate and loan term to see what you'll pay each month and over the life of the loan.

How accurate is a mortgage calculator?

Mortgage calculators are accurate for principal and interest when you enter the correct loan amount, rate and term. Estimates for property tax, insurance and PMI may vary by 10–20% depending on your county, credit score and lender.

Can a mortgage calculator show my actual loan approval amount?

Should I use a 15-year or 30-year mortgage calculator?

Run both. A 15-year mortgage cuts your total interest by 50–60% but raises your monthly payment by 40–50%.

Do mortgage calculators include closing costs?

Most mortgage calculators show monthly payments, not closing costs. Closing costs (2–5% of the loan amount) are paid up front and include origination fees, title insurance, appraisal, attorney fees and prepaid taxes.