What is inside a housing payment
A housing quote is several bills added together. Only some of them shrink as you repay the loan. When you compare two quotes, change only one of price, down payment, rate, term, tax, or insurance. The gap in the payment and in total interest is then the effect of that one choice. Changing several fields at once hides which one moved the bill. The sample amounts on the page are not a quote from a bank, a card issuer, or an employer. Replace them with the figures on your statement and run the page twice to see which field moves the result.
The part that is a loan
Principal and interest follow the mortgage page. A level payment keeps the monthly loan bill steady while the interest share falls.
Tax and insurance are not interest. They can rise even when the loan rate is fixed.
A 500,000 price with 100,000 down at 4% for 30 years borrows 400,000. The level payment is principal plus interest, and the first month is the most interest. Tax and insurance sit outside that payment. If the quote lists them, type them into the tax and insurance fields or the monthly total will not match the bill.
The down payment
A larger down payment lowers the amount borrowed and the interest. It does not change the tax rate.
If the quote includes mortgage insurance because the down payment is small, keep that cost next to the result. The calculator does not invent it.
Raising the down payment from 20% to 30% cuts the amount borrowed and the interest. It does not change the tax rate on the house. A small down payment sometimes adds mortgage insurance. The calculator does not invent that cost, so write it beside the monthly figure.
A longer term
Stretching the term lowers the monthly loan bill and usually raises total interest.
Run the same price twice and read both the payment and the interest line before you decide.
Run the same house and rate for 20 years and for 30 years. The 30-year payment looks smaller, and the interest total is usually larger. Affording the month and paying extra interest are different questions. Read both lines.
Related tools
These figures are estimates you can recompute from the formula on the page. They are not a lender quote, a tax bill, a payroll statement, or financial advice.