Mortgage Calculator – Your Real Monthly Housing Cost, PMI and Payoff Date
The rate a lender quotes only tells you part of what a house costs each month. This mortgage calculator starts from the home price and your down payment, works out the fixed principal-and-interest payment, then adds property tax, homeowners insurance, private mortgage insurance (PMI) and HOA dues to give the full monthly mortgage payment. It also builds the complete amortization schedule, shows when PMI drops off, and measures how much extra payments save.
What PITI means
Lenders describe a housing payment as PITI: principal (the part that pays down the loan), interest, property taxes and homeowners insurance. Taxes and insurance are often collected monthly into an escrow account and paid on your behalf. PMI and HOA dues sit on top of PITI when they apply, so the calculator shows each piece separately in the payment breakdown bar.
The mortgage payment formula
For a fixed-rate loan with monthly compounding, the principal-and-interest payment is M = L × r × (1 + r)^n ÷ ((1 + r)^n − 1), where L is the loan amount (price minus down payment), r is the annual rate divided by 12, and n is the number of monthly payments. At a 0% rate the formula simplifies to L ÷ n. For example, a $320,000 loan at 6.5% over 30 years gives $2,022.62 a month. Add 1.1% property tax ($366.67) and $1,800 a year of insurance ($150) and the real payment is $2,539.29.
Why early payments are mostly interest
Each month the lender charges interest on the balance still owed, and whatever is left of the fixed payment reduces the balance. At the start the balance is at its largest, so interest takes the biggest slice; in the example above, only about $289 of the first $2,022.62 payment goes to principal. As the balance falls, the interest share shrinks and the principal share grows. The per-year chart marks the year in which principal finally overtakes interest, and the balance chart shows how slowly equity builds in the first decade of a 30-year loan.
How PMI works and when it ends
On a conventional loan with less than 20% down (a loan-to-value ratio above 80%), lenders usually require PMI. The calculator charges it as an annual percentage of the original loan amount, split into monthly payments. Under the U.S. Homeowners Protection Act, PMI ends automatically when the original amortization schedule reaches 78% of the home's original value, and you may ask to cancel it once your actual balance reaches 80%. Only the 80% request date moves when you make extra payments. It also cannot run past the loan's midpoint. FHA mortgage insurance follows its own rules; choose the "Never" option to approximate life-of-loan premiums.
How extra payments shorten the loan
Money paid beyond the scheduled payment goes straight to principal, and every dollar of principal repaid early stops earning interest for the rest of the term. The "Pay it off faster" section accepts a monthly extra, a yearly extra in a chosen month and a one-time lump sum. The results compare against the same loan with no extras, reporting interest saved and time saved, and the balance chart draws the original path as a dashed line.
15-year vs 30-year mortgages
A shorter term raises the monthly payment but cuts total interest dramatically, because the balance falls faster and 15-year loans often carry lower rates. A 30-year loan keeps the required payment lower and leaves room in the budget, and you can still prepay it voluntarily. Switch between the term presets to compare the monthly cost, total interest and payoff date side by side.
Using the amortization schedule
The schedule groups payments by loan year, showing principal, interest, extra payments, PMI, the ending balance and your equity as a share of the purchase price. Expand any year to see its twelve months, or download the full monthly schedule as a CSV file to open in a spreadsheet.