Mortgage Calculator

Use this free mortgage calculator to estimate your monthly mortgage payment, see a full amortization schedule, factor in homeownership costs, and understand how extra payments can save you money.

What Is a Mortgage Calculator?

A mortgage calculator is a tool that helps you estimate the monthly payment on a home loan based on the home price, down payment, interest rate, and loan term. Beyond the basic principal-and-interest payment, it can also factor in additional homeownership costs — such as property taxes, home insurance, HOA fees, and private mortgage insurance (PMI) — to give you a more complete picture of your total monthly housing expense.

Mortgage Calculator vs. Amortization Calculator

This mortgage calculator and our Amortization Calculator share the same core amortization logic — they use the identical PMT formula and build the same month-by-month schedule of interest, principal, and remaining balance. The difference is scope:

• The amortization calculator focuses purely on the loan. You enter a loan amount, interest rate, and term, and it produces the monthly payment with a detailed amortization schedule. It also includes a full mathematical explanation of how the PMT formula works and why each payment splits the way it does. If you want to understand the math behind the calculations, that is the best place to start.
• The mortgage calculator wraps the same amortization engine in a homebuying context. It starts with the home price and down payment (rather than a raw loan amount), layers on housing-related costs, supports extra payments, and shows how those payments shorten your loan and save interest.

Because the underlying formulas are identical, we won't repeat the full mathematical derivation here. Please visit the Amortization Calculator for a step-by-step explanation of the PMT formula, period-by-period interest and principal allocation, and how the amortization schedule is constructed.

How to Use This Calculator

This calculator has three main sections. Here is a quick walkthrough to help you get started.

1. Basic Loan Details (Required)

These are the only fields you must fill in to get a result:

• Home Price — The total purchase price of the property.
• Down Payment — The amount you will pay upfront, entered as a dollar amount or a percentage of the home price. Toggle between the two modes with the button next to the field.
• Interest Rate — The annual interest rate for your mortgage.
• Loan Term — The length of the loan in years and/or months.
• Start Date — The month and year your first payment is due. This determines the dates shown in the amortization schedule.

Once you fill in these fields the calculator instantly shows your monthly principal-and-interest payment, total payment, and total interest.

2. Optional Costs — Homeownership Expenses

Expand the Optional Costs section to model additional monthly expenses that are part of homeownership. Four common US costs are pre-installed:

Each cost supports two input modes you can toggle between:

• Annual Percentage (%) — Enter a percentage of your home price. The calculator computes the annual amount and divides by 12 to get the monthly cost.
• Annual Fixed Amount ($) — Enter a flat annual dollar amount. The calculator divides by 12 for the monthly cost.

Important note for users outside the United States: The four pre-installed cost items (Property Tax, Home Insurance, HOA, and PMI) reflect common US homeownership expenses. If you are in a different country, your costs may differ — for example, you might have stamp duty, land tax, strata fees, or other region-specific charges. In that case, you can simply ignore or zero out the pre-installed items, and use the "Add Custom Cost" button to create your own line items with names and values that match your local situation. The calculation logic is the same regardless of the cost name — it is just a label attached to either a percentage or a fixed annual amount.

You can add as many custom costs as you need. All optional costs (pre-installed or custom) are summed into a single "monthly additional costs" figure that is added to your principal-and-interest payment to form the total monthly payment.

3. Extra Payments — Pay Off Your Loan Early

Extra payments are additional amounts you pay on top of your scheduled monthly payment. Any extra payment goes directly toward reducing your outstanding principal balance. Because interest each month is calculated on the remaining balance, a lower balance means less interest accrues in subsequent months.

This calculator supports three types:

1. Monthly extra payment — A fixed additional amount added to every monthly payment. Even a small extra amount each month can make a significant difference over a 30-year loan.
2. Yearly extra payment — A lump sum applied once per year in a month you choose (e.g., using a tax refund or year-end bonus). This reduces the balance once a year by a larger amount.
3. One-time extra payment — A single lump-sum payment made in a specific month and year (e.g., an inheritance or savings windfall). You can add as many one-time payments as you like.

All three types can be combined. The calculator tracks each extra payment in the amortization schedule and marks any month that includes an extra payment with a green "Extra" tag, with a tooltip showing the breakdown.

How Extra Payments Reduce Total Interest

The relationship between extra payments and interest savings is straightforward but powerful. Consider a $320,000 loan at 6% over 30 years:

• Without extra payments: You would pay approximately $370,000 in total interest over the life of the loan.
• With $200/month extra: The loan would be paid off roughly 6 years earlier, saving over $80,000 in interest.

The savings come from two compounding effects:

1. Lower balance → less interest each month. Since interest is calculated on the remaining balance, every dollar of extra principal immediately reduces the interest charged in the next period.
2. Shorter loan term. Because you are paying down principal faster, you reach a zero balance sooner, eliminating months (or years) of payments entirely.

The "Extra Payment Impact" section of this calculator quantifies both effects — showing you exactly how much interest you save and how many months you shave off the loan.