Mortgage Payment
Calculator

Understanding Your Mortgage Payment

A mortgage looks like a single number on your bank statement, but it's actually four separate things bundled together. Understanding each component is the difference between feeling like your money disappears every month and knowing exactly where every dollar is going.

The four parts of every mortgage payment (PITI)

When lenders and real estate professionals talk about your "monthly payment," they usually mean PITI — Principal, Interest, Taxes, and Insurance. Here's what each piece actually does:

Principal

Principal is the portion of your payment that reduces the actual loan balance. Every dollar of principal you pay is a dollar you'll never owe again, and a dollar of equity you've built in your home. In the early years of a 30-year mortgage, only a small fraction of each payment goes to principal — most of it goes to interest. This shifts dramatically over time, which is why the amortization schedule matters.

Interest

Interest is what the lender charges you for the privilege of borrowing the money. It's calculated each month based on your remaining loan balance. On a $320,000 mortgage at 7% interest, your very first monthly interest payment is roughly $1,867 — and your principal payment that same month is only about $263. As you pay down the balance, the interest portion shrinks and the principal portion grows. This is why making extra principal payments early in a loan saves enormous amounts of interest.

Taxes

Property taxes are levied by your county or municipality based on the assessed value of your home. They typically range from 0.5% to 2.5% of the home's value annually, depending on where you live. Most lenders collect property taxes monthly as part of your mortgage payment and hold them in an escrow account, then pay the tax bill on your behalf when it comes due. This protects the lender — if you stopped paying property taxes, the county could eventually seize your home, taking the lender's collateral with it.

Insurance

Homeowners insurance protects the property against fire, theft, weather damage, and liability. Like taxes, it's typically collected monthly and held in escrow. If your down payment is less than 20%, you'll also pay PMI (Private Mortgage Insurance) on top of homeowners insurance — this protects the lender if you default, not you. PMI typically costs 0.5% to 1.5% of the loan amount annually and can usually be cancelled once you reach 20% equity in the home.

How amortization actually works

Amortization is the process of paying off a loan through equal monthly payments over a set period. The math is counterintuitive: even though your monthly payment stays the same every month, the split between principal and interest changes dramatically over time.

Here's why. Interest is calculated each month on whatever the loan balance is at that moment. In month one of a 30-year, $320,000 loan at 7%, the balance is $320,000, so the interest charge is high. As you slowly pay down the balance, the interest charge each month gets smaller — and since your total payment is fixed, more of it goes to principal. By the final years of the loan, almost all of your payment is going to principal and almost none to interest.

This is why the calculator above generates a year-by-year breakdown. Looking at the schedule shows you something most people don't realize: on a typical 30-year mortgage, you don't cross the 50% point of paying down your principal until roughly year 20.

A worked example: $400,000 home in metro Atlanta

Let's run real numbers through a typical scenario. You're buying a $400,000 home in the Atlanta suburbs with 10% down. Property taxes in Henry County run about 1.0% annually, and homeowners insurance for a home this size is typically around $1,800 per year. Because you're putting less than 20% down, you'll also pay PMI of roughly 0.6% of the loan amount per year.

Over the full 30-year loan, you'll pay roughly $502,000 in interest alone — meaning the $400,000 home will cost you over $902,000 by the time it's paid off (not counting taxes, insurance, and inevitable maintenance). This isn't a horror story — it's just how mortgage math works at typical interest rates. But it's exactly why decisions like the size of your down payment, the loan term, and shopping aggressively for the lowest rate matter so much.

Fixed-rate vs. adjustable-rate mortgages

A fixed-rate mortgage locks in your interest rate for the entire loan term. Your principal-and-interest payment will be the same in year one as it is in year thirty. Fixed-rate is the dominant choice in the U.S. because it's predictable, and most homebuyers prioritize predictability over potential savings.

An adjustable-rate mortgage (ARM) typically offers a lower fixed rate for an initial period (often 5, 7, or 10 years), then adjusts annually based on a market index. A "5/1 ARM" means a fixed rate for 5 years, then annual adjustments. ARMs can save money if rates fall or if you plan to sell or refinance before the adjustment period ends. They can also be expensive if rates rise. ARMs make most sense for buyers who know they'll move within the fixed-rate window.

For most buyers planning to stay in their home for 7+ years, the fixed-rate mortgage is the safer bet — even when ARM rates look temptingly lower at signing.