Mortgage Calculator
Estimate principal-and-interest payments for a fixed-rate mortgage. Your work stays on this device whenever possible.
How to use Mortgage Calculator
- Enter Home purchase price ($) and Down payment (%) as a percentage, not a dollar figure; the loan amount is worked out for you.
- Fill Interest rate (%) and Loan term (years), from 1 to 40.
- Add Property tax ($/year) and Home insurance ($/year) so the monthly total covers more than principal and interest.
- Use Extra monthly payment ($) to test overpaying, then press "Calculate mortgage".
- Read the breakdown of principal and interest, taxes and insurance, and press "Download Schedule (CSV)" for the full amortization table.
Worked example
Enter price 350,000, down payment 10%, rate 6%, term 30 years, tax 4,200 and insurance 1,500. Down payment 35,000, loan 315,000, 360 payments at 0.5% monthly gives principal and interest of 1,888.58. Add 350.00 tax and 125.00 insurance for a total of 2,363.58. Total interest over 30 years is 364,890.30.
When to use this tool
- Comparing monthly costs across down payments of 5%, 10% and 20% on the same home.
- Budgeting for taxes and insurance alongside the loan payment before making an offer.
- Testing whether one extra payment per month is worth it over a 30-year term.
Important limitations
Property tax, insurance, closing costs, mortgage insurance, association fees, and local lending rules are not included.
Frequently asked questions
What is included in the monthly payment shown?
The estimate adds principal and interest to one twelfth of the yearly property tax and one twelfth of the yearly insurance, plus any extra payment. It is labelled Estimated Monthly Payment, not an official quote.
What is left out of the calculation?
Mortgage insurance, HOA dues, closing costs, discount points and escrow adjustments are not modelled. With a down payment below 20% many lenders add insurance, so real payments can be noticeably higher.
How are extra payments treated?
The extra sum is applied to principal every month, shortening the term. The result shows the new payoff time and the interest saved compared with the original schedule, based on the full-term interest figure.
Does the rate stay fixed for the whole term?
Yes. The tool assumes a fixed rate for every month. Adjustable-rate loans, interest-only periods and rate resets cannot be represented, so use it for fixed-rate comparisons only.
Why is the loan amount not equal to the price?
The down payment percentage is subtracted first. A 10% down payment on 350,000 leaves a 315,000 loan, and only that amount accrues interest, so raising the down payment cuts the interest total sharply.