Mortgage Calculator
🏠 Instantly calculate your monthly mortgage payment with full amortization schedule, payment breakdown, and extra payment savings.
Loan Details
Monthly Costs (Optional)
Your results will appear here
Enter your loan details and click Calculate Mortgage
🔧 How It Works
Calculate your complete mortgage cost in three simple steps
Enter Loan Details
Input your home price, down payment, interest rate, and loan term — along with optional taxes, insurance, and PMI
Instant Calculation
Click Calculate and get your monthly payment, total cost, and a full amortization schedule instantly
Analyze & Export
Review your payment breakdown, amortization schedule, and download the full results as a CSV file
How Is a Mortgage Payment Calculated?
Understanding the math behind your mortgage payment helps you make smarter borrowing decisions.
The Amortization Formula
A fixed-rate mortgage payment is calculated using the standard amortization formula. Given the principal P, monthly interest rate r, and number of payments n:
Where r = annual rate ÷ 12 and n = years × 12. This formula ensures equal monthly payments while the split between principal and interest shifts every month.
How Amortization Works
In the early years of a mortgage, the vast majority of each payment goes toward interest. As the loan balance decreases, the interest portion of each payment shrinks and the principal portion grows.
On a 30-year loan, roughly 75–80% of your first payment is interest. By the final year, nearly all of each payment is principal. This is why the first years of homeownership build equity slowly — and why extra payments early in the loan are so powerful.
The True Cost of a Mortgage — A Real-World Example
$400,000 home price
20% down ($80,000)
$320,000 loan
7.0% interest rate
30-year fixed
P&I: $2,129/mo
Total payments: 360
Total paid: $766,490
Total interest: $446,490
You pay 140% of the home price in interest alone over 30 years.
New P&I: $2,329/mo
Loan paid off: 25 yrs 1 mo
Total interest: $368,204
Save $78,286 and pay off 4 yrs 11 months early.
Who Uses This Mortgage Calculator?
From first-time buyers to seasoned property investors — here are the most common scenarios where this tool saves hours of manual calculation.
First-Time Home Buyers
Understand exactly what monthly payment you can afford before approaching a lender. Compare different home price points and down payment amounts to find the right balance for your budget.
Refinancing Decisions
Calculate whether refinancing makes financial sense by comparing your current mortgage payment against a new rate. See how much you will save monthly and when you break even on closing costs.
Extra Payment Planning
See the dramatic impact of making additional monthly principal payments. Discover how much interest you save and how many years you shave off your loan by paying just a little extra each month.
Down Payment Optimization
Compare 10%, 15%, and 20% down payment scenarios to find the sweet spot between minimizing your down payment and avoiding PMI — and understand the long-term cost of each choice.
Budget Planning
Get the full picture of your monthly housing cost including principal, interest, property taxes, insurance, and PMI — not just the base mortgage payment that lenders advertise.
Retirement Planning
Determine your mortgage payoff date and total interest cost to plan around a debt-free retirement. Use the amortization schedule to identify the best time to make lump-sum extra payments.
How to Reduce Your Total Mortgage Cost
Small changes at the right time can save tens or even hundreds of thousands of dollars over the life of your loan.
Put down at least 20% to eliminate PMI
Saves $1,600–$4,800/yearPMI typically costs 0.5%–1.5% of the loan amount annually. On a $320,000 loan, that is $1,600–$4,800 per year for zero equity benefit. Reaching 20% equity eliminates this cost permanently. Use this calculator to see exactly how much PMI costs you monthly and over time.
Make one extra payment per year
Saves ~$60,000+ over 30 yearsDividing your monthly payment by 12 and adding that amount to each payment (a 'biweekly equivalent' strategy) results in one extra full payment per year. On a 30-year $320,000 mortgage at 7%, this shaves approximately 4 years off your loan and saves over $60,000 in interest.
Buy mortgage points to lower your rate
Break even in ~5 yearsOne mortgage point costs 1% of the loan amount and typically reduces your rate by 0.25%. On a $320,000 loan, one point costs $3,200 and saves approximately $54/month. Your break-even point is about 59 months (5 years). If you plan to stay longer, buying points is worthwhile.
Refinance when rates drop 0.75%+
Calculate your break-evenA general rule of thumb is that refinancing makes financial sense when you can reduce your rate by at least 0.5%–0.75% and plan to stay in the home long enough to recoup closing costs (typically 2–5 years). Use this calculator to compare your current payment against a new rate.
Apply windfalls directly to principal
Saves ~$24,000 per $10K extraTax refunds, bonuses, and inheritance applied to mortgage principal provide a guaranteed return equal to your interest rate — higher than most low-risk investments. A single $10,000 lump-sum payment in year 5 of a 7% 30-year mortgage saves approximately $24,000 in total interest.
Common Questions About Mortgage Payments
Learn More — Guides & Related Resources
How to Calculate Your Mortgage Payment — Full Guide
Step-by-step walkthrough of the amortization formula with Python and JavaScript examples.
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Frequently Asked Questions
Everything you need to know about our mortgage calculator
Do I need to sign up or log in to use this tool?
No. All QuickTextTools are completely free to use online with no login, signup, or account required.
What is included in the monthly payment calculation?
The core monthly payment includes principal and interest (P&I) only. You can optionally add property tax, homeowner's insurance, and PMI to see your total monthly housing cost.
What is PMI and when do I need it?
PMI (Private Mortgage Insurance) is required by most lenders when your down payment is less than 20% of the home price. It protects the lender if you default. Typical PMI costs 0.5%–1.5% of the loan amount per year.
How does an extra monthly payment affect my mortgage?
Extra payments go entirely toward principal, reducing your loan balance faster. This shortens your loan term and significantly reduces total interest paid. Even $100 extra per month on a 30-year mortgage can save tens of thousands of dollars in interest.
What is an amortization schedule?
An amortization schedule is a complete table of every monthly payment over the life of the loan, showing how much goes to principal, how much goes to interest, and your remaining balance after each payment. Early payments are mostly interest; later payments are mostly principal.
Is my financial data sent anywhere?
Absolutely not. All calculations happen entirely in your browser using JavaScript. Your financial data never leaves your device and is never sent to any server.
What is the difference between interest rate and APR?
The interest rate is the cost of borrowing the principal. APR (Annual Percentage Rate) includes the interest rate plus other fees like origination fees, points, and mortgage broker fees. For monthly payment calculations, use the interest rate. APR gives a better picture of total loan cost.
How accurate is this mortgage calculator?
This calculator uses the standard amortization formula and produces accurate monthly payment figures for fixed-rate mortgages. For adjustable-rate mortgages (ARMs), only the initial rate period can be calculated accurately. Always consult a licensed mortgage professional for official loan estimates.
Can I calculate a 15-year mortgage?
Yes. Select 15 from the loan term options or enter 15 in the term field. A 15-year mortgage typically has a lower interest rate than a 30-year mortgage but a higher monthly payment — you build equity faster and pay far less total interest.
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