How to use the mortgage calculator
- Enter the home price and down payment, as a percentage or a dollar amount.
- Choose the loan term and interest rate. Pick 30, 20, 15 or 10 years, or Custom. Use the interest rate from your quote, not the APR.
- Set the first payment month; the payoff and PMI dates count from here.
- Add property tax, homeowners insurance and HOA dues. Property tax can be a percentage of the price or dollars per year.
- Check PMI. If you put down less than 20%, the calculator adds private mortgage insurance at the rate you enter and shows when it ends.
- Try extra payments (monthly, yearly or a one-time amount) to see the interest saved and the new payoff date. The schedule below switches between yearly and monthly rows.
How the monthly payment is calculated
A mortgage payment is often quoted as PITI: principal, interest, taxes and insurance. Principal and interest come from the standard amortization formula: the payment is fixed, interest is charged each month on the remaining balance at one twelfth of the annual rate, and the rest reduces the balance. Property tax and insurance are usually collected into an escrow account, so the calculator divides the yearly amounts by 12. PMI and HOA dues are added when they apply.
PMI (private mortgage insurance) is normally required on a conventional loan with less than 20% down. It is priced as a yearly percentage of the loan, so the calculator charges rate × original loan ÷ 12 a month. Under the federal Homeowners Protection Act, PMI on most conventional loans ends automatically when the balance is scheduled to reach 78% of the original value, and at the latest at the midpoint of the term; you can ask to cancel it at 80%. The calculator stops PMI at the 78% point. FHA and other government-backed loans have their own insurance rules, not modelled here.
Worked example
A $400,000 home with 20% down ($80,000) leaves a $320,000 loan. At 6.5% over 30 years, principal and interest are $2,022.62 a month. Property tax at 1% of the price is $4,000 a year ($333.33 a month) and insurance of $1,500 a year adds $125.00, so the full monthly payment is $2,480.95. Over 360 payments you pay $408,142 in interest.
Adding $200 a month to principal clears the same loan in 281 payments, 6 years and 7 months early, and cuts total interest by about $105,429.
With 10% down instead, the loan is $360,000, principal and interest are $2,275.44, and PMI at 0.5% adds $150 a month. The balance reaches 78% of the $400,000 value ($312,000) after 109 payments, so PMI stops in the tenth year.
Affordability: the 28/36 guideline
The helper below the schedule applies a common lender rule of thumb: the full housing payment up to 28% of gross monthly income, and housing plus other debt payments (car, student loan, card minimums) up to 36%. It finds the highest home price that fits both with your down payment, rate and costs. Lenders and loan programs set their own limits, so treat it as a starting point; you can change both percentages.
Why your lender's figure may differ
- Escrow amounts follow actual tax bills and premiums, which usually rise; the calculator keeps them constant.
- Rate versus APR: the payment uses the note rate; the APR also includes points and fees.
- Adjustable-rate loans change payment after the fixed period; this calculator assumes a fixed rate. Closing costs are not included.
- PMI pricing depends on credit score, loan-to-value and loan type.
- Taxes: mortgage interest is deductible only if you itemize, on up to $750,000 of acquisition debt ($375,000 if married filing separately). From 2026, PMI premiums are deductible again, phasing out between $100,000 and $109,000 of AGI. The calculator does not include these tax savings.
Related calculators
See what you take home each month with the US salary calculator or the paycheck calculator. Compare other borrowing with the loan calculator and the auto loan calculator, plan to clear cards first with the debt payoff calculator, or browse all salary and money calculators. Buying in the UK? Use the UK mortgage calculator.
Frequently asked questions
What is included in a monthly mortgage payment?
Usually principal and interest plus property tax and homeowners insurance held in escrow (PITI). PMI is added if you put down less than 20%, and HOA dues apply in many condos and planned communities, usually paid to the association rather than the lender.
When does PMI go away?
On most conventional loans PMI ends automatically when the balance is scheduled to reach 78% of the home's original value, and you can ask your lender to cancel it once you reach 80% if your payments are up to date. It ends at the midpoint of the loan term at the latest. Extra payments get you there sooner.
How much do extra payments save on a mortgage?
Extra principal payments shrink the balance that interest is charged on. In the example above, $200 a month extra on a $320,000, 30-year loan at 6.5% saves about $105,429 of interest and ends the loan 6 years and 7 months early. Check that your loan has no prepayment penalty.
Is a 15-year or 30-year mortgage better?
A 15-year loan has a higher payment but far less interest: $320,000 at 6.5% costs $2,787.54 a month over 15 years with $181,758 of total interest, against $2,022.62 and $408,142 over 30 years. Lenders often offer a lower rate on shorter terms, which widens the gap. A 30-year loan keeps the payment lower and you can still prepay.
How much house can I afford on my salary?
A common lender guideline is the 28/36 rule: keep the total housing payment under 28% of gross monthly income and all debt payments under 36%. Enter your income and debts in the affordability helper to turn that into a home price for your rate, down payment and local costs.
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