🏠 How Mortgage Payments Are Calculated (PITI Explained)

Your monthly mortgage payment is made up of more than just paying back what you borrowed. Lenders bundle several costs into one number, and understanding each piece is the difference between guessing what you can afford and actually knowing.

What Goes Into a Mortgage Payment? (PITI)

Most lenders quote a monthly payment that covers four things, known as PITI:

• Principal: the portion that pays down the amount you actually borrowed
• Interest: what the lender charges you for borrowing that money
• Property Tax: collected monthly and held in escrow, then paid to your local government
• Insurance: homeowners insurance, and mortgage insurance if your down payment is under 20%

The Mortgage Payment Formula

The principal-and-interest portion is calculated with a standard amortization formula: the loan amount, the monthly interest rate, and the number of payments determine a fixed monthly payment that pays off the loan exactly on schedule. You don't need to run this math by hand — that's exactly what a mortgage calculator does — but knowing the three inputs that drive it helps explain why your payment is what it is:

• Loan amount: home price minus your down payment
• Interest rate: even a 1% difference can change your payment by hundreds of dollars
• Loan term: spreading payments over more years lowers the monthly amount but increases total interest paid

How Loan Term Changes What You Pay

A shorter term means a bigger monthly commitment, but a dramatically smaller total interest bill over the life of the loan — often tens of thousands of dollars less.

Understanding Amortization

Early in a mortgage, most of each payment goes toward interest, not principal. As the loan balance shrinks, more of each payment shifts toward principal. This is why your loan balance seems to barely move in the first few years, even though you're making full payments every month — an amortization schedule makes this visible year by year.

The Role of Your Down Payment

A bigger down payment also directly reduces your loan amount — and therefore your monthly principal and interest — while lowering the total interest you'll pay over the full term.

Why Property Tax and Insurance Vary So Much

Unlike principal and interest, which are fixed by your loan terms, property tax and insurance depend on where you live and the home itself. This is why two people with an identical loan amount and rate can have noticeably different total monthly payments.

Step-by-Step: Calculate Your Mortgage Payment

1. Enter the home price and your planned down payment
2. Choose a loan term (30, 20, 15 or 10 years)
3. Enter the interest rate you've been quoted or expect to qualify for
4. Add estimated annual property tax and home insurance
5. Review your monthly payment, total interest, and full amortization schedule