Free Mortgage Calculator
Estimate your monthly payment, total interest, and full amortization schedule.
Balance & Interest Over Time
Amortization Schedule
| Year | Principal Paid | Interest Paid | Remaining Balance |
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Scenario A
Scenario B
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How It Works
Enter your loan details
Loan amount, interest rate, term, and down payment.
Click Calculate
Results appear instantly — nothing leaves your browser.
Review your breakdown
Monthly payment, total interest, and the full amortization schedule.
Understanding Your Mortgage Payment
A mortgage calculator estimates the monthly payment you'll owe on a home loan based on how much you borrow, the interest rate you're charged, and how long you have to repay it. Instead of guessing or waiting on a lender, you can see a reliable estimate in seconds and compare different scenarios before you ever apply.
Most fixed-rate mortgages use a method called French amortization (also known as an amortizing loan). Under this method, your payment stays the same every month for the life of the loan, but the mix inside that payment changes over time. Early on, most of each payment goes toward interest because your remaining balance is high. As you pay down the principal, the interest portion shrinks and more of each payment goes toward reducing the balance — which is why your equity builds slowly at first and faster in later years.
Three variables drive your monthly payment the most. The interest rate has an outsized effect: even a difference of half a percentage point can add tens of thousands of dollars in interest over a 30-year term. The loan term matters too — a shorter term means higher monthly payments but far less interest paid overall, while a longer term spreads the cost out and lowers the monthly payment at the expense of total interest. Finally, your down payment directly reduces the amount you borrow, lowering both your monthly payment and your total interest.
Choosing between a 15-year and a 30-year mortgage usually comes down to cash flow versus total cost. A 15-year loan gets you to full ownership faster and saves a substantial amount in interest, but demands a noticeably higher monthly payment. A 30-year loan is easier on monthly cash flow, which is why it's the most common choice for first-time buyers, but it costs more over the life of the loan.
You'll also see your Loan-to-Value ratio, or LTV — the amount you're borrowing divided by the value of the home, shown as a percentage. Lenders lean on LTV heavily when pricing a loan: a lower LTV (meaning you're putting more money down relative to the home's value) signals lower risk and typically earns better interest rates, while a higher LTV can require private mortgage insurance and a higher rate. Keeping an eye on your LTV is one of the simplest ways to understand how your down payment choice affects the total cost of homeownership.
Frequently Asked Questions
How is my monthly mortgage payment calculated?
Your monthly payment is calculated using the standard French amortization formula: M = P × r / (1 − (1 + r)^−n), where P is your loan amount minus your down payment, r is your monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments (loan term in years × 12). This produces a fixed payment for the life of the loan, with the mix of principal and interest shifting over time.
Should I choose a 15-year or 30-year mortgage?
A 15-year mortgage has a higher monthly payment but a much lower interest cost over time, saving you a large amount in total interest and building equity faster. A 30-year mortgage has a lower, more manageable monthly payment, freeing up cash flow, but costs significantly more in total interest. Choose 15 years if you can comfortably afford the higher payment and want to be debt-free sooner; choose 30 years if you value payment flexibility or want to invest the difference elsewhere.
How does the down payment affect my monthly payment?
A larger down payment reduces the amount you actually borrow (the principal), which directly lowers both your monthly payment and the total interest you'll pay over the life of the loan. A down payment of 20% or more can also help you avoid private mortgage insurance (PMI) and may qualify you for a better interest rate.
What is LTV and why does it matter?
LTV, or Loan-to-Value ratio, is the amount you're borrowing divided by the home's value, expressed as a percentage. Lenders use LTV to gauge risk: a lower LTV (meaning a bigger down payment) usually means better interest rates and loan terms, while a higher LTV can require mortgage insurance and carries a higher rate.
Can I use this calculator for refinancing?
Yes. Enter your current remaining loan balance as the Loan Amount, set Down Payment to $0, and use the new interest rate and term you're considering. The calculator will show your new estimated monthly payment and amortization schedule under the refinanced terms.
How accurate is this mortgage calculator?
This calculator uses the same French amortization formula lenders use to compute principal and interest payments, so the numbers are mathematically accurate for that formula. It does not include property taxes, homeowners insurance, HOA fees, or PMI, so your actual total monthly housing cost from a lender may be higher. Use it as a solid estimate for principal and interest, not a binding loan offer.