How to Use a Mortgage Calculator
Enter the home price, down payment, interest rate, loan term, property tax, and insurance to estimate the monthly mortgage payment. The calculator separates principal and interest from monthly tax and insurance, then returns the related totals for a positive loan amount.
What the mortgage calculator does
Use the Mortgage Calculator to estimate a monthly payment from the figures that shape the calculation: home price, down payment, interest rate, loan term, annual property tax, and annual insurance. These inputs are optional, so you can begin with a basic estimate and add tax and insurance when you have those figures available.
The result separates monthly principal and interest from monthly property tax and insurance. It also shows the loan amount, total monthly amount, total interest, and total payment when the loan amount is positive.
How to use the mortgage calculator
- Enter the home price. Enter the down payment as the amount you plan to pay upfront.
- Enter the interest rate as a percentage and the loan term in years.
- Add annual property tax and annual insurance if you want those costs included in the monthly estimate.
- Review the entered values, then run the calculation.
- Read the returned figures. The loan amount is calculated by subtracting the down payment from the home price. Annual property tax and annual insurance are each divided by 12 for their monthly portions.
If you leave fields blank, the calculator uses its declared defaults: 0 for home price, down payment, property tax, and insurance; 6.5 for interest rate; and 30 years. A home price of 0 or less is replaced with $300,000 before calculation. A negative interest rate is replaced with 0, and the years value is converted to a whole number with a minimum of one year.
For a zero-interest calculation, monthly principal and interest equals the loan amount divided by the number of monthly payments. The returned monetary figures are rounded to two decimal places.
How to read the result
For a positive loan amount, compare the monthly principal-and-interest figure with the monthly tax and insurance amounts. Their combined figure is the total monthly amount returned by the calculator. Total interest and total payment provide longer-term figures for the same calculation.
A down payment equal to or greater than the home price is not treated as a normal payment calculation. In that case, the calculator returns an error indication instead of the normal payment figures. Check that the home price and down payment reflect the intended scenario, then calculate again.
The estimate covers the stated principal, interest, property tax, and insurance inputs. It does not represent other mortgage-related costs beyond those calculations, and it should not be treated as financial advice or a guarantee of accuracy.
Worked example
For a $400,000 home with an $80,000 down payment, a 6.5% rate, a 30-year term, $6,000 in annual property tax, and $1,200 in annual insurance, enter those values and run the calculation.
Enter the scenario inputs, run the calculation, and review the returned payment and total fields.
The result contains loan amount, monthly principal and interest, monthly tax, monthly insurance, total monthly amount, total interest, and total payment, with monetary figures rounded to two decimal places.
Limitations
- The calculation covers principal, interest, property tax, and insurance from the stated inputs; it does not cover mortgage costs beyond those items.
Common errors
- If the down payment is equal to or greater than the home price, the loan amount is not positive and the normal payment figures are not returned. Reduce the down payment or enter the intended higher home price, then run the calculation again.
FAQ
What information do I need to calculate a mortgage payment?
The calculator accepts home price, down payment, interest rate, loan term in years, property tax, and insurance. Each input is optional.
What happens if I leave the mortgage calculator fields blank?
The declared defaults are 0 for home price, down payment, property tax, and insurance; 6.5 for interest rate; and 30 years. A home price of 0 or less is then replaced with $300,000 during calculation.
Why did the calculator not return a normal payment?
No normal payment figures are returned when the down payment is equal to or greater than the home price. The calculator returns an error indication for that condition.