Mortgage Payment Calculator

Estimate monthly principal and interest for a fully amortizing, fixed-rate mortgage. Enter the amount borrowed, nominal annual interest rate, and loan term. This estimate excludes property taxes, homeowners insurance, mortgage insurance, HOA fees, and loan fees.

Calculate a mortgage payment

Use the loan amount after any down payment, not automatically the home's purchase price. Enter the note interest rate, not an APR that incorporates fees. All money amounts are in US dollars.

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Mortgage payment formula

For a positive monthly rate:

M = P x r / (1 - (1 + r)^-n)

M: monthly principal and interest payment.
P: loan principal.
r: monthly rate as a decimal, equal to nominal annual percentage / 1,200.
n: number of monthly payments, equal to whole years x 12.

At a 0% rate, use M = P / n. The formula models equal monthly payments on a fully amortizing loan, not every mortgage arrangement.

For a step-by-step formula and payment examples, read our guide to calculating a mortgage payment.

Worked example

For a $300,000 loan at an illustrative 6% fixed annual rate over 30 years, the estimated monthly principal and interest payment is $1,798.65. Total interest is approximately $347,514.57 using the unrounded payment over 360 months. These figures are examples, not a current rate offer or a lender quote.

Principal and interest versus the full payment

Your actual monthly payment may also include property taxes, homeowners insurance, mortgage insurance, and other charges. HOA fees may be paid separately. This tool does not calculate those amounts, escrow, affordability, eligibility, or closing costs.

Use a lender's estimate and applicable loan documents to compare complete costs. The interest rate alone does not describe all borrowing costs.

Frequently asked questions

Should I enter the home price or loan amount?

Enter the amount actually borrowed. A down payment reduces the amount financed, while any financed fees can increase it. Confirm the principal in your loan documents; this tool does not calculate a down payment automatically.

Is the interest rate the same as APR?

Not necessarily. APR can reflect fees and other borrowing costs. This formula requires the fixed nominal annual note rate under the monthly-rate convention stated here.

Does this support adjustable rates, interest-only loans, or balloon payments?

No. It assumes a fixed rate and full monthly amortization over the term. Different loan structures need different models.

Are biweekly payments or extra payments included?

No. This version models monthly payments only. Paying every two weeks, paying twice per month, or making extra principal payments can work differently depending on the calendar and how the lender applies them.

Does the payment change during the term?

The theoretical principal-and-interest payment is fixed under this model. The portions going to principal and interest change as the loan amortizes. Taxes, insurance, or other actual charges can change separately.

Why might my lender show a different amount?

Differences can arise from rounding, dates, daily interest, rate conventions, financed fees, payment timing, and loan terms. The final payment may be adjusted in a real schedule.

What inputs are supported?

Loan principal greater than zero and up to $100,000,000, with up to two decimals. Annual rate from 0% to 30%, with up to four decimals. Term is 1 to 50 whole years. Use a decimal point or comma without currency symbols or thousands separators.

HandyMetric provides general calculations, not personalized mortgage, tax, or financial advice, loan approval, or a lender quote. Verify assumptions and full costs before making borrowing decisions.