Math

Mortgage payment calculator.

Your full monthly payment — principal, interest, tax, insurance and HOA — plus lifetime interest.

This is a planning estimate, not financial advice or a loan offer. It doesn't include PMI, and a lender's quote will reflect your exact rate, fees and escrow.

What goes into the payment

A mortgage payment is usually quoted as "PITI" — principal, interest, taxes and insurance. The principal-and-interest part comes from the loan amount, rate and term using the standard amortisation formula; taxes and insurance are added on top, typically collected monthly into an escrow account. The numbers worth watching: a longer term lowers the monthly payment but sharply increases the total interest, and putting less than 20% down usually means paying private mortgage insurance (PMI) until you build enough equity. This is an estimate for planning — your lender's quote will reflect your exact rate, fees and escrow. To see the upfront cash, use the cash-to-close estimator; to work backwards from income, try affordability.

The amortisation formula

The principal-and-interest portion comes from M = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1], where P is the amount borrowed, r is the monthly interest rate (the annual rate divided by 12) and n is the total number of monthly payments. A 30-year loan means n = 360.

The payment stays level, but its composition does not. Early on, most of each payment is interest; the principal share grows month by month. That is why overpaying in the first few years removes far more total interest than the same overpayment made later.

A worked example, and what the term costs you

Borrow $350,000 at 6.5% over 30 years and the principal-and-interest payment is about $2,212 a month. Across the full term you repay roughly $446,000 in interest — more than the house cost.

Take the same loan over 15 years and the payment rises to about $3,049, but total interest falls to roughly $199,000. The shorter term costs about $837 more each month and saves around $247,000 overall. That trade — monthly affordability against lifetime cost — is the single biggest decision in the whole mortgage.

Beyond principal and interest

  • Taxes and insurance. Usually collected monthly into escrow and added on top of the P&I figure, which is why a lender quote looks higher than a bare amortisation calculation.
  • PMI. With less than 20% down, private mortgage insurance is typically charged until you build sufficient equity. It protects the lender, not you.
  • HOA dues. Not part of the mortgage at all, but they come out of the same monthly budget.
  • Rate type. A fixed rate keeps the payment level; an adjustable one can reset, so the figure here reflects only the current rate.

This is a planning estimate. Your lender's Loan Estimate is the document with the real numbers, including fees this calculator does not model.

FAQ

How is a monthly mortgage payment calculated?
Principal and interest use the amortisation formula M = P·r·(1+r)ⁿ / ((1+r)ⁿ−1), where P is the loan, r the monthly rate and n the number of payments. Property tax, insurance and any HOA are then added on top.
Do I pay PMI with less than 20% down?
Usually yes. Conventional loans typically require private mortgage insurance when your down payment is under 20%, and it drops off once you reach about 20% equity. The calculator flags this but doesn't add a PMI figure, since the rate varies.
What is the mortgage payment formula?
M = P × [r(1+r)^n] ÷ [(1+r)^n − 1], where P is the loan amount, r is the monthly rate (annual rate divided by 12) and n is the total number of monthly payments. A 30-year loan has n = 360. This gives principal and interest only; taxes and insurance are added separately.
How much does a 15-year term save?
On a $350,000 loan at 6.5%, a 30-year term costs about $2,212 a month and roughly $446,000 in total interest. A 15-year term costs about $3,049 a month but only about $199,000 in interest — around $247,000 less, for roughly $837 more each month.
Why is my lender quote higher than this calculator?
Because a lender quote usually includes property taxes, homeowner's insurance and, with less than 20% down, mortgage insurance, all collected monthly into escrow. It may also reflect fees and a rate specific to your credit profile. This calculator estimates principal and interest plus the taxes and insurance you enter.

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