How to Calculate Your Monthly Mortgage Payment
Automated technical check: . Scope and review policy
A fixed-rate mortgage's principal-and-interest payment depends on the amount borrowed, the annual interest rate and the number of payments. Start with the loan amount, not the home's price. The Mortgage Calculator adds separately entered taxes, insurance, HOA charges and optional mortgage insurance to that loan payment.
The formula and its inputs
M = P x r / [1 - (1 + r)-n], where P is principal, r is the annual interest rate expressed as a decimal divided by 12, and n is the number of monthly payments. At zero interest, M = P / n. Use the loan's interest rate here, not an APR that also incorporates certain fees.
$400,000 home with 20% down
The down payment is $80,000 and the loan is $320,000. At an illustrative 7% fixed interest rate over 30 years, r = 0.07 / 12 and n = 360. Keeping precision until the end gives a P&I payment of $2,128.97, with modeled interest of $446,428.47 over the original term. Keep intermediate powers and rates unrounded, then round the final displayed amount.
If annual property taxes are $3,600 and annual insurance is $1,500, their monthly equivalents are $300 and $125. With no HOA or mortgage insurance in this example, modeled monthly housing payment is $2,553.97. These costs are explicit assumptions, not national averages, and they can change even when P&I remains fixed.
Compare rates on the same loan
| Example interest rate | Monthly P&I | Modeled total interest |
|---|---|---|
| 5.5% | $1,816.92 | $334,092.93 |
| 6% | $1,918.56 | $370,682.20 |
| 6.5% | $2,022.62 | $408,142.36 |
| 7% | $2,128.97 | $446,428.47 |
| 7.5% | $2,237.49 | $485,495.11 |
These are scenarios, not current offers. Compare actual Loan Estimates, including fees and the time you expect to keep the loan. A smaller payment by itself does not prove a cheaper loan.
Match the calculator to your quote
- Enter the price and down-payment percentage so the displayed principal matches the financed amount.
- Enter the quoted interest rate and term; check P&I against the lender's figure.
- Add actual tax, insurance and HOA amounts. Enable the PMI estimate only when it applies to your loan.
- Use the Amortization Calculator for annual balances and recurring extra principal, or compare 15- and 30-year terms.
Origination fees, points, reserves, closing cash, maintenance and changes to tax or insurance are not all represented by the headline payment. The estimate does not determine affordability, approval or a lender's legally required disclosure.