How to use the Mortgage Calculator
Fill in the fields above and the result appears straight away. Everything runs in your browser, so nothing you type is uploaded.
The formula
M = P × r ÷ (1 − (1 + r)^−n), with r the monthly rate and n the number of payments.
Examples
- $400,000 home, 20% down, 6.5%, 30 years
Total monthly payment: $2,547.62 Principal and interest: $2,022.62 Property tax: $400.00 Insurance: $125.00
- Same home on a 15-year term
Total monthly payment: $3,312.54 Principal and interest: $2,787.54 Property tax: $400.00 Insurance: $125.00
- Same home with only 10% down
Total monthly payment: $2,800.44 Principal and interest: $2,275.44 Property tax: $400.00 Insurance: $125.00
Limitations and assumptions
Does not include private mortgage insurance (usually due below 20% down), closing costs or rate changes on adjustable loans.
Frequently asked questions
How is a mortgage payment calculated?
Principal and interest use the standard loan formula M = P × i × (1+i)^n ÷ ((1+i)^n − 1), where i is the monthly rate and n the number of payments. Taxes and insurance are added monthly.
How much house can I afford?
Lenders often look at housing costs below roughly 28 percent of gross income and total debts below about 36 to 43 percent. Treat these as rules of thumb.
Does a bigger down payment lower the payment?
Yes, and below 20 percent down many lenders add mortgage insurance, which this estimate does not include.
What does a shorter term do?
Monthly payments rise but total interest drops sharply.