Mortgage Calculator

How to Use the Mortgage Calculator

The Mortgage Calculator helps you estimate monthly payments, total interest costs, and the full amortization schedule for a home loan. Whether you are buying your first home or refinancing, this tool provides the financial clarity you need to make informed decisions.

Required Inputs

Enter the home price, down payment amount or percentage, annual interest rate, and loan term in years. Common loan terms are 15 and 30 years. The calculator instantly computes your monthly payment, breaking it down into principal and interest components.

The Mortgage Payment Formula

Monthly payments are calculated using the standard amortization formula: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ - 1], where M is the monthly payment, P is the loan principal, r is the monthly interest rate (annual rate / 12), and n is the total number of payments (years × 12). For a $300,000 loan at 6.5% over 30 years: r = 0.065/12 = 0.005417, n = 360, giving M ≈ $1,896.20.

Understanding the Amortization Schedule

The amortization table shows how each monthly payment is split between principal and interest over the life of the loan. In early years, most of your payment goes toward interest. Over time, the principal portion grows. For the example above, the first payment puts about $1,271 toward interest and only $625 toward principal.

Down Payment Impact

A larger down payment reduces your loan amount, monthly payment, and total interest paid. Putting 20% down also eliminates private mortgage insurance (PMI), saving an additional $100-$300 per month on most loans. Compare scenarios with different down payment amounts to find the right balance.

Additional Costs to Consider

Your actual monthly housing cost includes property taxes, homeowner insurance, HOA fees, and possibly PMI. While this calculator focuses on the loan itself, budget an additional 25-35% above the base payment for these expenses.

Frequently Asked Questions

Q: Should I choose a 15-year or 30-year mortgage?

A: A 15-year mortgage has higher monthly payments but saves substantially on total interest. A $300,000 loan at 6% costs about $177,000 in interest over 15 years versus about $347,000 over 30 years. Choose based on what monthly payment fits your budget comfortably.

Q: How much does the interest rate affect my payment?

A: Even small rate differences have a big impact. On a $300,000 30-year loan, going from 6% to 7% increases your monthly payment by about $200 and total interest by roughly $72,000 over the life of the loan.

Q: What is an amortization schedule?

A: An amortization schedule is a complete table of every payment over the loan term, showing the date, payment amount, principal portion, interest portion, and remaining balance for each month. It illustrates how your loan balance decreases over time.