How the mortgage calculator works
A mortgage is an amortizing loan: you pay the same amount every month, but early payments are mostly interest and later ones are mostly principal. The principal-and-interest portion is found with this formula:
M = P · r / (1 − (1 + r)−n)
- M — monthly principal & interest
- P — loan amount (price − down payment)
- r — monthly interest rate (annual rate ÷ 12)
- n — number of monthly payments (years × 12)
On top of principal and interest, this calculator adds your monthly property tax, homeowners insurance, and any HOA dues to show the real number that leaves your account each month — your full PITI payment.
Principal, interest, taxes, and insurance
Lenders qualify you on total housing cost, not just the loan. Property taxes vary widely by location and are usually a percentage of your home's assessed value; homeowners insurance protects the structure; and HOA dues, where they apply, cover shared amenities. Bundling all four into one figure gives a truer picture of affordability than principal and interest alone.
How to lower your monthly payment
- Put more down. A larger down payment shrinks the loan and can eliminate PMI above 20%.
- Shop the rate. Even a quarter-point lower rate saves thousands over 30 years — get quotes from several lenders.
- Consider the term. A 30-year loan minimizes the monthly payment; a 15-year loan minimizes total interest.
- Mind taxes and insurance. These can shift your payment by hundreds a month and vary a lot by area.
A quick example
Buy a $525,000 home with 15% down ($78,750) at 7% over 30 years and you borrow $446,250. Principal and interest come to about $2,969 a month; add roughly $481 in property tax and $175 in insurance and the full payment lands near $3,625. Over the life of the loan you'd pay about $622,600 in interest — more than the home's price, which is why the rate and term matter so much.
Frequently asked questions
How is a monthly mortgage payment calculated?
The principal-and-interest portion uses the amortizing loan formula M = P·r / (1 − (1 + r)^−n), where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments. Property tax, homeowners insurance, and HOA dues are then added to get your full monthly payment.
What does PITI mean?
PITI stands for Principal, Interest, Taxes, and Insurance — the four parts of a typical monthly mortgage payment. Lenders look at your total PITI (plus HOA, if any) when deciding how much you can borrow, since it represents the real cost of owning the home each month.
How much should my down payment be?
A 20% down payment lets you avoid private mortgage insurance (PMI) on a conventional loan and lowers your monthly payment. Many buyers put down less — some loan programs allow 3–5% — but a smaller down payment usually means PMI and more interest over the life of the loan.
Does a shorter loan term save money?
Yes. A 15-year mortgage has a higher monthly payment than a 30-year loan but charges far less total interest, because you borrow for half as long and often at a lower rate. The trade-off is less monthly cash flow flexibility.
What is included in property tax and insurance here?
You enter your annual property tax and annual homeowners insurance; the calculator divides each by 12 and adds them to your monthly payment. Lenders usually collect these in an escrow account along with your principal and interest.
Disclaimer: This calculator provides estimates for educational purposes only and is not a loan offer or financial advice. Actual rates, taxes, insurance, and fees vary by lender and location.