What Will My House Payment Be? Estimate It

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

Formula

The calculator uses the standard fixed-payment loan formula:

Monthly payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the loan principal, in dollars.
• r is the monthly interest rate, calculated as annual APR ÷ 1,200. For an APR entered as a percentage, 8% becomes 0.08 ÷ 12, or about 0.006667 per month.
• n is the number of monthly payments: loan term in years × 12.

Total interest is estimated as monthly payment × number of payments − principal. The displayed payment is rounded to cents; the total-interest output uses that displayed rounded payment. The formula assumes equal monthly payments over the full term.

Worked Example

Using the calculator’s default inputs—$20,000 borrowed, 8% APR, and a 5-year term:

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

Under these assumptions, the estimated principal-and-interest payment is $405.53 per month, and estimated interest over the term is $4,331.80.

Assumptions

• The APR remains fixed for the entire loan term.
• Payments are made monthly, with the first payment one month after borrowing.
• Interest is compounded monthly using APR ÷ 12.
• The calculation excludes fees, taxes, homeowners insurance, mortgage insurance (PMI), and escrow. It also does not model a down payment or closing costs; enter the amount actually borrowed as the loan amount.

What Counts as a House Payment?

“House payment” can mean either the loan payment or the full amount paid toward housing each month. The calculator gives only principal and interest. Principal reduces the amount owed; interest is the cost of borrowing under the assumed APR and schedule.

A complete monthly housing budget may also include property taxes, homeowners insurance, mortgage insurance, homeowners association dues, utilities, and maintenance. Some taxes or insurance may be collected alongside a mortgage payment through escrow, but they are separate from the principal-and-interest calculation. Their amounts depend on the property, location, coverage, and payment arrangements, so use actual estimates or figures provided for the home when working out a fuller monthly budget.

How to Get a Useful Estimate

Use the principal you expect to borrow, not automatically the home’s purchase price. A down payment reduces the amount financed, while other amounts included in the loan can increase it. Get the proposed APR, loan term, and any financed charges from the lender or loan disclosure rather than treating the example defaults as a quote.

• Check that the APR is entered as a percentage: enter 6.5 for 6.5%, not 0.065.
• Enter the term in years. A 30-year term is 30, not 360; the formula converts years to months.
• Compare the same loan amount, APR, and term when examining payment estimates. Changing any one of these changes the result.
• Estimate taxes, insurance, and other recurring costs separately to understand the broader monthly housing outlay.

The outputs are estimates to the nearest cent, not a statement of the amount a borrower will be approved for or ultimately owe. Actual loan documents may include fees, different payment timing, a changing rate, or other terms that this fixed-rate calculation does not represent.

Why the Payment Changes

For a given principal and APR, extending the term generally lowers the scheduled monthly principal-and-interest payment because repayment is spread over more months. It also means more payments are made, so total interest can be higher. A shorter term usually has the opposite pattern: a higher scheduled payment and fewer months of interest accrual. These are consequences of the formula, not a recommendation about which term to choose.

At a fixed term and principal, a higher APR raises the monthly payment and total interest. A larger principal raises both as well. The payment is not simply principal divided by the number of months, because each payment also covers interest calculated on the remaining balance.

Common Estimate Gaps

A frequent misunderstanding is to treat the calculator’s payment as the full monthly cost of owning a home. It is not: no property tax, insurance, association fee, maintenance, or utility input appears in the calculator. Another common error is entering the purchase price when the loan amount is lower because of a down payment, or higher because certain costs are financed.

Rounding also matters. The displayed monthly payment is rounded to cents, and multiplying it by the number of payments gives the total paid under this estimate. The lender’s actual payment schedule may differ by a small amount because of its exact calculation conventions, payment dates, or contract terms. Variable rates, extra payments, missed payments, and refinancing are outside this model.

Frequently Asked Questions

Does this estimate include property taxes and homeowners insurance?
No. It estimates principal and interest only. Add separate monthly estimates for taxes, insurance, and any other recurring housing costs to estimate a broader total.

Should I enter the home price or the loan amount?
Enter the amount borrowed. If you make a down payment, the loan amount is generally less than the purchase price; financed charges or other adjustments can change it.

Why is my lender’s quoted payment different?
The quote may include escrow items or other charges, or may use different loan terms, payment timing, or rate assumptions. Compare the principal-and-interest portion and check the lender’s disclosure for the exact inputs.

How does the loan term affect the monthly payment?
With the same principal and APR, a longer term spreads repayment across more monthly payments and generally lowers each scheduled payment, while increasing the number of months over which interest accrues.

Is APR the same as the interest rate?
Not always. APR is a yearly measure that can reflect certain borrowing costs in addition to the stated interest rate, depending on the loan terms. This calculator uses the APR entered as if it were the fixed annual rate for monthly amortization, so the estimate may not reproduce a lender’s full APR-based disclosures.

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

Related

• PA Budget Late Payment Calculator and Guide
• Monthly House Payment Plan Calculator and Formula
• One-Off Budget Payment Calculator

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