How is the monthly mortgage payment calculated?

The standard formula is M = P × [r(1+r)^n] / [(1+r)^n - 1], where P is the loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the total number of payments (years × 12). Our calculator does this math instantly as you type.

How much can I save with extra payments?

Even small extra payments can save tens of thousands in interest. For example, adding $200/month to a $350,000 loan at 6.5% over 30 years saves roughly $82,000 in interest and pays off the loan about 6 years early. Enter your own numbers to see your savings.

What is the difference between a 15-year and 30-year mortgage?

A 15-year mortgage has higher monthly payments but much lower total interest. A 30-year mortgage has lower payments but costs more over the life of the loan. Our calculator lets you compare terms side by side to find the right balance.

What is amortization?

Amortization is the process of paying off a loan through regular payments over time. In the early years, most of each payment goes toward interest. As the loan matures, more goes toward principal. The amortization breakdown in our calculator shows exactly how this shifts over time.

Are my financial details private?

Yes. All calculations run in your browser. Your loan amount, interest rate, and payment details are never sent to any server. We do not sell leads or connect you with lenders. This is a tool, not a sales funnel.

Does this include property tax and insurance?

The core calculation focuses on principal and interest (P&I). You can optionally add property tax, insurance, and PMI estimates to see a more complete monthly payment picture. These are entered as annual amounts and divided by 12.

Free Mortgage Calculator Online

Calculate your monthly mortgage payment, total interest, and see how extra payments save you money

We Added 6 Calculators. None of Them Want to Sell You a Mortgage. →

What the Mortgage Calculator Does

Buying a home is one of the biggest financial decisions most people will ever make, and understanding the real cost of a mortgage is essential before signing anything. This free online mortgage calculator breaks down your monthly payment, total interest, and overall loan cost so you can make informed decisions with clear numbers in front of you.

Whether you are a first-time homebuyer trying to figure out what you can afford, a homeowner considering a refinance, or someone comparing 15-year vs. 30-year terms, this tool gives you instant answers. Enter your loan details and watch the results update in real time — no forms to submit, no accounts to create, and no lender waiting on the other end.

Your financial details are 100% private. Every calculation runs entirely in your browser. Your loan amount, interest rate, income, and payment information are never sent to a server, stored in a database, or shared with third parties. This is a calculator, not a lead-generation funnel.

How It Works

Getting started takes about ten seconds. Here is a step-by-step walkthrough of the interface:

Enter your loan amount in the top field. This is the amount you plan to borrow — typically the home price minus your down payment. Type a number like 350,000 and results begin calculating immediately.
Set the interest rate as an annual percentage. Enter your expected or quoted rate (for example, 6.5) in the field next to the loan amount.
Choose a loan term by clicking one of the three preset buttons: 15yr, 20yr, or 30yr. The selected term highlights instantly so you can compare options with a single click.
Add an extra monthly payment (optional). Below the core inputs, the Extra monthly payment field lets you enter any additional amount you plan to pay each month beyond the minimum. Even modest amounts here can produce dramatic savings.
Expand taxes and insurance by clicking the Show taxes & insurance toggle. This reveals three additional annual fields — Property tax/yr, Insurance/yr, and PMI/yr — which are divided by 12 and added to your monthly total. When these fields are populated, the results header switches from “Monthly payment (P&I)” to “Monthly payment (all-in)” so you can see the complete picture.
Review your results. The results panel displays your monthly payment in large text, with total interest and total cost shown below. A principal vs. interest bar provides a visual breakdown of where your money goes over the life of the loan, with exact percentages for each.
See extra payment savings. If you entered an extra payment, a highlighted savings panel appears showing your new payoff timeline, years saved, and total interest saved — all color-coded for quick scanning.
Explore the amortization table. Click Year-by-year amortization to expand a detailed table showing principal paid, interest paid, and remaining balance for each year of the loan. This reveals how early payments are interest-heavy and gradually shift toward principal.
Copy or clear. The Copy button in the results header copies your key figures as formatted text for pasting into notes, emails, or spreadsheets. The Clear all button at the bottom resets every field to start fresh.

Why Use Our Mortgage Calculator

Most mortgage calculators on the web exist to collect your information and connect you with lenders. Ours does not. Here is what sets it apart:

No signup, no email, no phone number. You get results immediately without handing over personal information.
Client-side processing. All math happens in your browser using the standard amortization formula. Nothing is transmitted to any server.
Extra payment modeling built in. Many basic calculators skip this entirely, but seeing the impact of extra payments is one of the most valuable things a mortgage calculator can do.
Taxes, insurance, and PMI included. The expandable advanced section gives you a realistic all-in monthly number rather than just principal and interest.
Year-by-year amortization. The collapsible table shows how your balance decreases and how the principal-to-interest ratio shifts over time — up to 30 years of data.
No ads disguised as results. The output is your numbers and nothing else.

Use Cases

First-time homebuyers exploring affordability. Plug in different home prices and down payment amounts to see what monthly payment fits your budget before you start shopping.
Comparing loan terms side by side. Click between 15yr, 20yr, and 30yr to instantly see how the term length affects your monthly payment and total interest. A 15-year term has higher payments but can save you six figures in interest over the life of the loan.
Modeling the impact of extra payments. Enter $100, $200, or $500 as an extra monthly payment and see exactly how many years you shave off and how much interest you save. The results are often surprising — small amounts compound into major savings.
Refinance analysis. If you are considering refinancing at a lower rate, enter your remaining balance and the new rate to compare your current payment against the potential new one.
Budgeting for total housing costs. Expand the taxes and insurance section to factor in property tax, homeowners insurance, and PMI. This gives you the full monthly number you will actually owe, not just the loan payment.
Sharing numbers with a partner or advisor. Use the Copy button to grab a clean summary of your payment breakdown and paste it into a message, document, or spreadsheet for discussion.

Tips and Best Practices

Use your actual quoted rate, not an average. National averages are useful for rough estimates, but your real rate depends on your credit score, down payment, and lender. If you have a pre-approval letter, use that number.
Do not forget about PMI. If your down payment is less than 20%, most conventional loans require Private Mortgage Insurance. Add your estimated annual PMI in the advanced section to avoid underestimating your true monthly cost.
Test the extra payment field aggressively. You might be surprised to find that an extra $150 per month on a 30-year loan can save you $50,000 or more in interest and cut five or more years off your payoff date. Run the numbers before dismissing the idea.
Compare total cost, not just monthly payment. A 30-year mortgage has a lower monthly payment than a 15-year, but the total interest paid is dramatically higher. The total cost and total interest figures help you see the full picture beyond the monthly budget line.
Remember this is an estimate. The calculator provides accurate math based on your inputs, but actual loan terms, escrow amounts, and fees vary by lender. Use these numbers as a planning tool and confirm details with your mortgage provider before making commitments.

Frequently Asked Questions

How is the monthly mortgage payment calculated?: The standard formula is M = P × [r(1+r)^n] / [(1+r)^n - 1], where P is the loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the total number of payments (years × 12). Our calculator does this math instantly as you type.
How much can I save with extra payments?: Even small extra payments can save tens of thousands in interest. For example, adding $200/month to a $350,000 loan at 6.5% over 30 years saves roughly $82,000 in interest and pays off the loan about 6 years early. Enter your own numbers to see your savings.
What is the difference between a 15-year and 30-year mortgage?: A 15-year mortgage has higher monthly payments but much lower total interest. A 30-year mortgage has lower payments but costs more over the life of the loan. Our calculator lets you compare terms side by side to find the right balance.
What is amortization?: Amortization is the process of paying off a loan through regular payments over time. In the early years, most of each payment goes toward interest. As the loan matures, more goes toward principal. The amortization breakdown in our calculator shows exactly how this shifts over time.
Are my financial details private?: Yes. All calculations run in your browser. Your loan amount, interest rate, and payment details are never sent to any server. We do not sell leads or connect you with lenders. This is a tool, not a sales funnel.
Does this include property tax and insurance?: The core calculation focuses on principal and interest (P&I). You can optionally add property tax, insurance, and PMI estimates to see a more complete monthly payment picture. These are entered as annual amounts and divided by 12.