Mortgage Calculator
What is a Mortgage Calculator?
A mortgage calculator estimates your full monthly home payment: principal and interest, property taxes, homeowners insurance and private mortgage insurance (PMI) when your down payment is under 20%. It is the number you compare with your budget before house hunting.
Numbers make this concrete. Take the default scenario: a $350,000 home with 20% down leaves a $280,000 loan. At 6.5% over 30 years, the principal and interest payment is about $1,770 per month. Add $3,500 in annual property tax ($292 a month) and $1,500 in insurance ($125 a month) and the full payment lands near $2,186. Over 30 years, interest alone totals roughly $357,000 - more than the loan itself. Drop the down payment to 10% and the loan grows to $315,000, pushing principal and interest to about $1,991 plus a $131 monthly PMI charge until you reach 20% equity.
Working the calculator takes about a minute. Enter the home price, choose your down payment as a percentage, set the interest rate and term, then add your expected annual property tax and insurance. The results break the payment into line items: principal and interest, the monthly share of taxes and insurance, PMI when your down payment is under 20%, and the combined total, with the lifetime interest figure below. Changing any single input - the rate, the term, the down payment - instantly shows how sensitive the payment is to that one decision.
First-time buyers use it to test what price range their budget supports, current owners use it to weigh refinancing or a shorter term, and it is handy for comparing two houses with different tax burdens. The estimate deliberately excludes several real-world costs: HOA dues, closing costs, maintenance, utilities, and any adjustments to PMI after you cross the 20% equity line. It assumes a fixed rate for the whole term and taxes that never rise. Treat the output as a strong planning baseline rather than a lender-accurate quote, and ask a lender for exact figures once you get serious.
Frequently Asked Questions
How is a mortgage payment calculated?
The principal and interest portion uses the amortization formula: M = P × r(1 + r)^n / ((1 + r)^n - 1). On top of that, most buyers pay 1/12 of their annual property tax and insurance each month, plus PMI if their down payment is under 20%.
What is PMI and when do I stop paying it?
Private mortgage insurance protects the lender when your down payment is under 20%. It typically costs 0.5-1% of the loan amount per year and automatically drops off once you build 20% equity, or can be removed at that point by request.
How much house can I afford?
A widely used guideline is the 28/36 rule: keep your housing payment under 28% of gross monthly income and total debt payments under 36%. Lenders also evaluate your credit score and debt-to-income ratio when approving your loan.
Should I put 20% down?
Putting 20% down avoids PMI and lowers your loan amount, but it is not mandatory - many programs allow 3-10% down. The tradeoff is paying PMI and carrying more debt. Run your numbers both ways to see which makes sense for you.
How much interest will I pay on a 30-year mortgage?
More than most buyers expect. On a $280,000 loan at 6.5%, total interest is roughly $357,000 over 30 years - greater than the original balance, because early payments are mostly interest. A 15-year term cuts lifetime interest dramatically but raises the monthly payment.
Can I pay extra on my mortgage each month?
Yes, and extra payments go directly to principal unless your lender says otherwise. Even one extra payment per year can shorten a 30-year loan by several years. Check that your loan has no prepayment penalty, which is rare on standard US mortgages today.