Mortgage Calculator
Estimate the monthly principal and interest on a fixed-rate loan. Taxes, insurance, and mortgage insurance are not included. The labels and the result are in dollars.
Read the guide: What the mortgage calculator leaves out
How to use
- Enter the home price and the down payment. The loan amount is price minus down payment. A down payment larger than the price is treated as a zero loan.
- Enter the annual interest rate and the term in years. The term field allows 1 to 40. The default is 30.
- Click Calculate Payment. The large figure is the monthly principal and interest. The line under it shows the loan amount, total interest, and total paid.
The formula
This is the standard fixed-rate payment. Let P be the loan amount (price minus down payment), r the monthly rate (annual rate divided by 12), and n the number of months (years times 12).
M = P × r × (1 + r)n / ((1 + r)n − 1)
If the annual rate is 0, the payment is simply P / n. The result is rounded to cents. Total interest is rounded to the nearest dollar in the detail line. There is no amortization table, no extra principal payment, and no adjustable rate.
The inputs are labeled in dollars, and the result is prefixed with $. You can type another currency's numbers, but the page will not convert them and will still print a dollar sign. It does not look up today's mortgage rate.
A worked example
The fields start at a home price of $350,000, a down payment of $70,000, an annual rate of 6.5%, and 30 years. The loan is $280,000. That is exactly 20% down. The monthly principal and interest is $1,769.79. Total interest over 360 payments is about $357,125. Total paid is about $637,125.
That $1,769.79 is not the check you would write. A lender's monthly amount also includes property tax, homeowner's insurance, and sometimes mortgage insurance or HOA dues. Those are not fields on this page. A rate quote that is 6.5% with points is also not the same as typing 6.5 here, because points change what you pay up front and this page has no field for them.
Change only the rate to see the interest effect. The same $280,000 for 30 years at 5.5% is a lower payment, and at 7.5% a higher one. The page does not tell you which rate you qualify for.
When not to use this
- You need a full housing payment with tax and insurance. Add those yourself on top of this result.
- The loan is interest-only, adjustable, or has a balloon. This formula does not describe those loans.
- You want an amortization schedule or a biweekly payment. This page has neither.
- You are comparing loans in a currency other than dollars and the $ prefix would be misleading. The math is the same, the label is not.
Questions
Does the payment include tax and insurance?
No. It is principal and interest only. A mortgage statement is usually higher because of escrow for tax and insurance.
What if my down payment is less than 20%?
The math still runs. Many lenders then add mortgage insurance. This page does not estimate that premium.
Why does the detail line not match cents on the interest?
The monthly figure uses cents. Total interest and total paid in the detail line are rounded to the nearest dollar.