Estimated House Payment Per Month Calculator

This calculator estimates a monthly principal-and-interest payment from a home loan amount, annual interest rate, and term. Enter those figures to see the estimated payment and total interest; property taxes, homeowners insurance, mortgage insurance, and other housing costs are not included.

Formula

The monthly payment is calculated as a fixed-payment loan, also called an amortizing loan. The formula is:

Payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the amount borrowed, in dollars.
• r is the monthly interest rate, calculated as APR ÷ 1,200. For example, an 8% annual rate gives a monthly rate of 0.006667.
• n is the number of monthly payments, calculated as the loan term in years × 12.

The result is rounded to the nearest cent. Estimated total interest is the rounded monthly payment multiplied by the number of payments, minus the original loan amount. The APR input is treated as a nominal annual rate divided into monthly periods; the calculation does not add lender charges or convert an APR that includes fees into a separate interest rate.

Worked Example

Using the calculator’s default values—$20,000 borrowed, 8% APR, and a five-year term—the loan has 60 monthly payments. Its monthly rate is 8 ÷ 1,200 = 0.0066667.

1. Set P = $20,000, r = 0.0066667, and n = 5 × 12 = 60.
2. Apply the formula: $20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰].
3. The monthly payment is approximately $405.53.
4. Total interest using the rounded payment is $405.53 × 60 − $20,000 = $4,331.80.

This is an illustration of the formula, not a suggested borrowing amount or rate. The actual figures for a home purchase must come from the loan terms provided by the lender.

Assumptions

• The interest rate stays fixed for the full term.
• Payments are made monthly, at the end of each monthly period.
• Interest compounds monthly at APR ÷ 12.
• The calculation excludes fees, taxes, homeowners insurance, mortgage insurance, escrow, and other costs because there are no inputs for them.

What a House Payment Estimate Includes

In this calculator, “monthly payment” means principal and interest only. Principal pays down the amount borrowed; interest is the charge for borrowing. A home’s full monthly housing expense can be higher because homeowners may also pay property taxes, homeowners insurance, mortgage insurance, homeowners association dues, and maintenance costs. Which expenses are billed with a mortgage payment varies by loan and billing arrangement.

For a broader budget estimate, gather the expected amounts for each relevant expense and convert annual amounts to monthly amounts by dividing by 12. Add those monthly figures to the calculator’s principal-and-interest result. Treat this as a separate estimate: amounts such as taxes, insurance premiums, or association dues may change, and this calculator does not forecast those changes.

How to Choose Inputs and Read Results

• Loan amount: Enter the amount financed, not automatically the home’s purchase price. A down payment, if any, affects the amount borrowed, while closing costs or other financed charges may affect it too.
• APR: Enter the annual percentage rate specified for the loan scenario. Do not substitute a monthly rate or enter “8” as a decimal “0.08”; the calculator expects a percentage, so an 8% rate is entered as 8.
• Term: Enter the number of years over which the fixed monthly payments are scheduled. A longer term generally spreads repayment over more payments; at the same positive rate and principal, it changes both the payment and total interest.
• Monthly payment: This is the formula’s estimated principal-and-interest amount, rounded to cents. It is not a complete estimate of the cash needed each month to own the home.
• Total interest: This is the sum of rounded scheduled payments less the original principal. It assumes every scheduled payment is made as calculated and the loan is not changed or paid off early.

For instance, a $300,000 loan at 6% APR for 30 years has an estimated principal-and-interest payment of about $1,799 per month, before taxes, insurance, and other costs. The example is arithmetic only; use the rate and loan amount for the scenario being assessed rather than treating it as a market quote.

Why a Real Mortgage Bill Can Differ

A lender’s quoted payment may not match this estimate if the quoted figure includes escrow, mortgage insurance, fees, a different payment schedule, or a rate structure other than the calculator’s fixed-rate assumption. An adjustable rate can change over time, while a fixed-rate calculation assumes the rate does not change. A payment may also be affected by the final loan amount, the exact rate and term, payment dates, and rounding conventions.

Another frequent misconception is that APR and the interest rate are always interchangeable. This calculator uses APR as the annual rate input and divides it by 12 for monthly interest. In lending disclosures, APR may reflect certain charges in addition to the note interest rate, so using the disclosed APR in this simplified formula may not reproduce the lender’s principal-and-interest schedule exactly. Ask the lender which rate applies to the payment quotation and compare like-for-like figures.

Limits and Common Input Mistakes

This is a standard fixed-payment formula, not a mortgage approval tool or a complete homeownership-cost calculator. It does not determine eligibility, account for changing rates, model extra payments, calculate a payoff balance, or include property-specific expenses. The displayed total interest also assumes the scheduled payment remains constant through the full term.

• Entering the purchase price instead of the amount financed can overstate the payment when a down payment reduces the loan.
• Entering 0.08 for an 8% APR treats the input as 0.08%, not 8%.
• Using an annual term as if it were months changes the number of payments; this calculator asks for years and converts them to months.
• Rounding an intermediate rate or payment by hand can produce a small difference. The calculator rounds the payment to cents and uses that rounded payment for total interest.

To compare a calculator estimate with a lender’s paperwork, check that the principal, rate, term, and included costs all refer to the same loan scenario. The lender’s disclosure gives the exact figures for that offer.

Frequently Asked Questions

What is included in an estimated house payment?
This calculator includes principal and interest only. Taxes, homeowners insurance, mortgage insurance, association dues, and other costs must be added separately if they apply.

How do I estimate a payment if I know the home price?
First determine the loan amount for the scenario, accounting for any down payment and amounts financed. Enter that loan amount, the applicable annual rate, and the term. The result is not based on purchase price alone.

Does a longer mortgage term lower the monthly payment?
For the same principal and positive rate, spreading repayment across more months generally lowers the calculated monthly principal-and-interest payment. It also means more payments and can increase total interest over the full schedule.

Is APR the same as the mortgage interest rate?
Not necessarily. APR can account for certain loan charges as well as interest, depending on the disclosure. This calculator uses the entered APR directly as its nominal annual rate, so its result may differ from a lender’s payment calculation.

Why does my lender’s payment differ from this estimate?
The lender may use a different rate or loan amount, include escrow or insurance, account for fees, or quote a payment under different terms. Confirm which items are included in each figure before comparing them.

This result is an estimate, and the lender’s disclosure gives the exact figures.

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in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
out pmt | Monthly payment | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2