What Is My House Payment? Estimate the Monthly Cost

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

Formula

The calculator uses the standard fixed-payment loan formula. It converts the annual percentage rate (APR) to a monthly rate, then calculates the payment needed to repay principal and interest in equal monthly installments:

Payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the loan principal, in dollars.
• r is the monthly interest rate as a decimal: APR ÷ 1,200. For an 8% APR, r = 8 ÷ 1,200.
• n is the number of monthly payments: term in years × 12.

Total interest is calculated as the rounded monthly payment multiplied by the number of payments, minus the original principal: Total interest = payment × n − P. Since the payment is rounded to cents, the total is an estimate based on that rounded amount.

Worked Example

Using the calculator’s default inputs—$20,000 principal, 8% APR, and a five-year term:

1. Convert the APR to a monthly decimal rate: 8 ÷ 1,200 = 0.0066667.
2. Find the number of monthly payments: 5 × 12 = 60.
3. Substitute into the payment formula: $20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰] = $405.53 per month, rounded to cents.
4. Estimate total interest using that rounded payment: $405.53 × 60 − $20,000 = $4,331.80.

The calculator’s headline result is therefore $405.53 per month, with estimated total interest of $4,331.80.

Assumptions

• The APR stays fixed for the full term.
• Payments are equal, made monthly, with the first payment one month after the loan begins.
• Interest is modelled monthly at APR ÷ 12.
• The estimate excludes fees, property taxes, homeowners insurance, mortgage insurance (PMI), escrow, and other charges because they are not inputs.

What a House Payment Includes

People use “house payment” to mean different things. In a loan calculation, it often means principal and interest: principal pays down the amount borrowed, while interest is the cost of borrowing. A household’s full monthly housing bill may also include property taxes, homeowners insurance, mortgage insurance, homeowners association dues, utilities, or maintenance. Those costs vary and are not calculated here.

For example, a $405.53 loan payment in this example does not mean the total monthly cost of owning the home is $405.53. A lender or mortgage servicer may collect some tax and insurance amounts through an escrow account, but escrow is a method of collecting and paying those bills, not additional loan principal. To estimate a broader monthly budget, add separately verified monthly amounts for costs that apply to the property.

How to Use and Read the Estimate

Enter the amount you expect to borrow—not automatically the home’s purchase price. A down payment reduces the amount financed, while financed costs can increase it. Use the APR and term shown in the lender’s loan disclosure or quote for a closer arithmetic estimate. APR can reflect certain borrowing costs in addition to the interest rate, but this calculator treats the entered APR as the rate applied monthly; it does not separately model fees or their timing.

The output is the scheduled level payment for principal and interest under the stated assumptions. It is not a statement of how much a lender will approve, nor does it determine whether a payment fits a particular budget. Actual amounts depend on the final loan terms and any included or separately billed housing costs.

• Loan amount: Increase it and, all else equal, the calculated payment rises.
• APR: A higher entered rate raises the payment for the same principal and term.
• Term: A longer term generally lowers the scheduled payment but means more payments are made. With a fixed rate, it can also increase total interest.

Common Mistakes and Limits

A frequent mistake is treating the principal-and-interest estimate as the entire house payment. Check which items a lender’s quoted payment includes, and avoid adding an escrow amount twice if taxes or insurance are already included in that quote. Another common error is entering a percentage incorrectly: type 8 for 8%, not 0.08, because the calculator expects APR as a percentage.

Rounding also matters. The displayed payment is rounded to the nearest cent, and the total-interest result uses that rounded payment multiplied by the full number of months. A real amortization schedule may have a slightly different final payment because of payment dates, daily interest calculations, rounding at each step, rate changes, or servicing adjustments. This calculator assumes a fixed rate and does not model adjustable-rate changes, skipped or late payments, extra principal payments, or closing costs.

The entered APR must be positive because the formula divides by the monthly rate. The term is converted from years to months, so a term such as 30 years represents 360 scheduled payments. The calculation is general loan arithmetic; it does not supply a market rate, property-specific tax bill, insurance premium, or lender fee. Get those figures from the lender and relevant bill or provider rather than inferring them from this result.

Frequently Asked Questions

Is a house payment just principal and interest?
Not always. A calculator or quote may show principal and interest alone, while a household’s total monthly housing cost can also include taxes, insurance, mortgage insurance, association dues, and other expenses. Check what a specific quoted payment includes.

How do I calculate my monthly house payment?
Use the fixed-payment formula with the loan principal, monthly rate (annual APR divided by 1,200), and number of monthly payments. This calculator applies that formula and rounds the payment to cents.

Does this estimate include property taxes and insurance?
No. Taxes, homeowners insurance, mortgage insurance, and escrow are not inputs. Add applicable monthly amounts separately to estimate a broader housing bill.

Why is my lender’s payment different?
The lender’s figure may use a different final principal, rate, term, payment date, rounding method, or included costs. Compare the assumptions and confirm the exact breakdown in the lender’s disclosure.

Does a longer mortgage term lower the monthly payment?
For the same principal and fixed APR, extending the term generally lowers the scheduled principal-and-interest payment because repayment is spread across more months. It also increases the number of payments, and the total interest can be higher.

This result is an estimate; 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 | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2