How is a monthly mortgage payment calculated?
A fixed-rate mortgage payment is M = P × r × (1 + r)^n ÷ ((1 + r)^n − 1), where P is the loan amount (home price minus down payment), r is the yearly rate divided by 12 and n is the number of monthly payments. Property tax, home insurance and HOA fees are added on top to get the full monthly cost. FixDoks's Mortgage Calculator does this and shows how much interest you pay each year.
Mortgage Calculator at a glance
| Inputs | Home price, down payment, rate, term, tax, insurance, HOA |
|---|---|
| Output | Monthly payment, total interest, amortization schedule |
| Processing | In your browser; your files are not uploaded |
| Price | Free |
| Works on | Chrome, Edge, Safari and Firefox on Windows, Mac, Android and iPhone |
How to use Mortgage Calculator
- Enter the home price and your down payment, as a percentage or an amount.
- Enter the interest rate your lender quoted and the loan term in years, for example 30 or 15.
- Optionally add yearly property tax and home insurance, and any monthly HOA or service charge.
- Read the monthly payment and total interest, then open the schedule to see each year's principal, interest and balance.
What goes into a monthly mortgage payment?
Most home loans are repaid in equal monthly instalments. Each payment covers the interest due for that month, and the rest reduces the loan balance (the principal). Early in the loan most of the payment is interest; by the final years most of it is principal. On top of the loan payment, many homeowners also pay property tax, home insurance and, for flats or planned communities, a monthly association or service charge. In the United States these are often collected together as PITI: principal, interest, taxes and insurance.
The formula
M = P × r × (1 + r)n ÷ ((1 + r)n − 1)
- P is the amount you borrow: the home price minus your down payment.
- r is the monthly interest rate: the yearly rate divided by 12, as a decimal.
- n is the number of payments: years × 12.
Worked example
A home costs 400,000 and you put 20% down, so you borrow 320,000 at 6.5% a year for 30 years.
- Monthly principal and interest: 2,022.62
- Total interest over 30 years: about 408,142
- The same loan over 15 years costs 2,787.54 a month, but total interest falls to about 181,758.
Small rate differences matter over a long term. At 6.0% instead of 6.5%, the same 320,000 loan costs 1,918.56 a month, which is 104.06 less each month and about 37,460 less over 30 years.
How the down payment changes things
A bigger down payment means a smaller loan, a lower monthly payment and less interest overall. In the United States, conventional lenders usually require private mortgage insurance (PMI) when the down payment is below 20% of the price, until you build up 20% equity. PMI is not included in this calculator because it depends on the lender and your credit; ask your lender for the figure and add it to the monthly fees box if you want a complete total.
Using the amortization schedule
The schedule shows, for every year or every month, how much of your payments went to interest and to principal, and what you still owe. Use it to see how much equity you would have after five or ten years, or to compare a 15-year and a 30-year loan side by side. You can download the monthly schedule as a CSV file for a spreadsheet.
What this calculator does not include
- Adjustable or variable rates: the result assumes the rate stays fixed for the whole term.
- Closing costs, arrangement fees, stamp duty or transfer taxes, which vary by country and lender.
- Tax relief on mortgage interest, where your country offers it.
Treat the result as an estimate for planning and comparing offers. Your lender's official quote is the figure to rely on.