Formula
Loan amount = home price − down payment. Monthly principal-and-interest payment = P × r × (1 + r)^n ÷ ((1 + r)^n − 1), where P is loan principal, r is monthly interest rate and n is total monthly payments. If r = 0, payment = P ÷ n.
Mortgage Payment Calculator
Estimate a monthly principal-and-interest mortgage payment from loan amount, interest rate and term, with optional tax and insurance fields.
Worked example
Home price 500,000 minus down payment 100,000 gives a 400,000 loan. At 6.5% annual interest, the monthly rate is 0.065 ÷ 12. Over 30 years there are 360 payments, so the fixed principal-and-interest payment is about 2,528.27. Adding 400 property tax and 150 insurance gives an estimated all-in monthly housing figure of about 3,078.27.
Professional note
Master’s Tip: print a rate comparison before speaking to a lender. A one-point rate change can move the monthly payment enough to affect affordability, even when the loan amount and term stay the same.
Regional and unit assumptions
Standard or basis: transparent fixed-rate amortising loan arithmetic with monthly payments. The page does not claim APR disclosure compliance, tax treatment, lender approval, affordability assessment or local mortgage-product rules.
Assumptions and limitations
- The payment formula estimates fixed-rate principal and interest only before optional monthly tax and insurance fields are added.
- The annual rate is converted to a monthly rate by dividing by 12.
- Payments are assumed monthly and level across the selected term.
- Closing costs, lender fees, mortgage insurance, offset accounts, escrow rules, variable-rate changes, refinance costs and local taxes are not included unless entered as simple monthly costs.
- This is planning arithmetic only, not lending, legal, tax or financial advice.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Loan amount = home price − down payment. Monthly principal-and-interest payment = P × r × (1 + r)^n ÷ ((1 + r)^n − 1), where P is loan principal, r is monthly interest rate and n is total monthly payments. If r = 0, payment = P ÷ n.
Standard or basis
Standard or basis: transparent fixed-rate amortising loan arithmetic with monthly payments. The page does not claim APR disclosure compliance, tax treatment, lender approval, affordability assessment or local mortgage-product rules.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Master’s Tip: print a rate comparison before speaking to a lender. A one-point rate change can move the monthly payment enough to affect affordability, even when the loan amount and term stay the same.
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Questions
How do you calculate a mortgage payment?
Subtract the down payment from the home price to get the loan amount, convert the annual rate to a monthly rate, then apply the fixed-payment loan formula across the total number of monthly payments.
Does this include property tax and insurance?
The principal-and-interest payment is calculated separately. Optional monthly property tax and insurance fields are then added to show a fuller housing-cost estimate.
What happens if the interest rate is zero?
With a zero rate, the calculator divides the loan amount evenly by the number of monthly payments.
Is this the same as an APR calculation?
No. APR can include fees and disclosure rules. This page uses a simple fixed-rate loan payment formula and states what is excluded.
Why does the term length matter so much?
A longer term spreads the loan across more payments, which usually lowers the monthly payment but can increase total interest paid over the life of the loan.
Calculation note
Mortgage payment arithmetic is a practical use of the annuity formula: one present loan balance is repaid through many equal payments. It is useful for house-hunting, lender conversations, classroom finance and affordability notes, but the result is only a formula estimate until real lender terms are confirmed.
The loan amount comes first
The calculator separates home price and down payment because buyers often compare properties by price, while the payment formula needs the actual borrowed principal. Keeping both figures visible makes the printable report easier to review later.
Monthly payments are an annuity calculation
A fixed-rate mortgage payment is built so each payment covers that month’s interest and pays down some principal. Early payments carry more interest; later payments carry more principal as the balance falls.
Taxes, insurance and lender rules are separate layers
A household budget usually needs more than principal and interest. The optional tax and insurance fields keep those amounts visible, but they are simple monthly additions rather than a legal escrow or APR model.
Rate sensitivity is the useful comparison
The same loan can look affordable or stretched under different rates. Showing nearby rates helps the page beat generic calculators by making the risk of rate assumptions visible before the estimate is printed.