How is the monthly mortgage payment calculated?

Monthly payments are calculated using the PMT formula: M = P × [r(1+r)^n] / [(1+r)^n − 1], where P is the loan principal, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments (years × 12).

What is included in a mortgage payment?

This calculator computes principal and interest (P&I) only. Your actual monthly payment may also include property taxes, homeowner's insurance, and PMI if your down payment is less than 20%.

How much down payment do I need?

Conventional loans typically require 5–20% down. FHA loans allow 3.5%. A larger down payment reduces your loan amount, monthly payment, and total interest paid.

What is an amortization schedule?

An amortization schedule shows how each payment is split between principal and interest over the life of the loan. Early payments are mostly interest; later payments are mostly principal.

How can I reduce my total interest paid?

You can reduce total interest by making a larger down payment, choosing a shorter loan term, or making extra principal payments. Even one extra payment per year can save thousands in interest.

Mortgage Calculator

Home Price ($)

Down Payment ($)

Annual Interest Rate (%)

Loan Term (years)

Mortgage Calculator — FAQ

About the Mortgage Calculator

The CalcFi mortgage calculator is a free tool that helps homebuyers and homeowners calculate their exact monthly mortgage payments, total interest cost, and view a complete amortization schedule. It uses the standard PMT formula trusted by banks and financial institutions worldwide.

To use the calculator, simply enter the home price, your down payment, the annual interest rate offered by your lender, and the loan term. The calculator instantly shows your monthly payment broken down by principal and interest, plus the total cost of the loan over its lifetime.

For example, a $400,000 home with a 20% down payment ($80,000), a 6.5% interest rate, and a 30-year term results in a monthly payment of approximately $2,023. Over 30 years, you'll pay roughly $728,000 total — meaning $408,000 in interest on top of the $320,000 loan.

Use this calculator when comparing mortgage offers from different lenders, deciding on a loan term (15 vs 30 years), or evaluating how a larger down payment affects your monthly budget. All calculations happen instantly in your browser — no data is sent to any server.

No registration required
Available in English & Spanish
Updated for 2026
Mobile-friendly

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