Mortgage Calculator

1. Enter values in Home price ($), Down payment ($), Annual interest rate (%), and Loan term (years).
2. Add any Annual property tax ($, optional), Annual home insurance ($, optional), Monthly HOA fee ($, optional), or Monthly mortgage insurance ($, optional) amounts. Blank optional fields count as zero.
3. Choose Amortization schedule for the regular schedule, or Extra-payment payoff to test additional principal.
4. In payoff mode, enter Recurring extra principal per month ($, optional) or One-time extra principal payment ($, optional). A one-time payment also needs Applied in month # (1 = first payment).
5. Click Calculate, then review the result. Use Copy result or Download result (.txt) for the plain-text summary and schedule.

How Mortgage Calculator sets the payment

The loan amount is the home price minus the down payment. The annual rate becomes a monthly rate, and the term becomes a rounded count of monthly payments. At 0% interest, the payment is the loan amount divided by that count.

Payment = Loan amount x r / (1 - (1 + r)^-n)

For example, these values produce this principal-and-interest result:

Home price: $350,000
Down payment: $70,000
Annual interest rate: 6.5%
Loan term: 30 years
Loan amount: $280,000
Principal & interest / month: about $1,769

Home price must be above 0, and down payment must be below it. The annual rate accepts 0 to 100. The term must produce 1 to 720 monthly payments. Every optional amount must be 0 or greater; an invalid value stops the calculation and shows an error.

How taxes, HOA, and PMI enter the result

Mortgage Calculator divides Annual property tax ($, optional) and Annual home insurance ($, optional) by 12. It adds Monthly HOA fee ($, optional) as entered. Those amounts affect the initial total monthly payment and stay outside the loan balance.

Monthly mortgage insurance is active when the month's starting balance is above 80% of the home price. It drops after the balance reaches 80% or less. Check each row in the PMI active column.

How extra principal changes the payoff

Extra-payment payoff compares the standard schedule with a schedule that includes your additional principal. Recurring extra principal applies each month. One-time extra principal applies in the month you enter. The comparison shows payoff time, the change in months, total interest, and interest saved.

When a one-time amount is greater than zero, Applied in month # (1 = first payment) must be 1 or greater. A month beyond the generated schedule is accepted and has no effect. Payoff mode also requires a recurring or one-time amount greater than zero.

What the two modes show

Amortization schedule shows the regular payment, formula, assumptions, payoff time, total interest, and schedule rows. Each row includes principal and interest, extra applied, remaining balance, and PMI status.

Extra-payment payoff compares the standard and extra-payment schedules at the same fixed rate. Enter a recurring or one-time amount to see the payoff and interest difference.

Mortgage Calculator and related tools

Browse Financial Calculators for a different money calculation. Choose the Amortization Calculator for a period-by-period schedule from an existing balance, rate, term, and payment frequency. Choose the House Affordability Calculator when income, debts, down payment, and your debt-to-income thresholds should estimate a home price. Choose the Refinance Calculator to compare a current mortgage with a proposed refinance.

The calculation stays in your browser and uses the values you enter. The script does not fetch live rates, lender records, or credit data, and it does not assess affordability, approval, or refinancing offers.

Frequently asked questions