Mortgage Calculator.

Guide

How to use the Mortgage Calculator

This calculator builds the full monthly housing payment, not just the loan, because that's the number your budget cares about.

1. Enter the Home price, then your Down payment as either dollars or a percent. The two fields are linked; changing one updates the other.
2. Set the Loan term (10 to 40 years) and the Interest rate you've been quoted. Set the First payment date so the payoff date and schedule follow the calendar.
3. Enter Property tax as a percent of the home price per year, and Homeowners insurance in dollars per year.
4. Check the PMI rate. The calculator applies it automatically when the down payment is under 20% and removes it once the balance reaches 80% of the price.
5. Add HOA dues if the property has them. They don't go to the lender, but you pay them every month.
6. Optionally open Extra payments and add an amount in Extra every month, Extra once a year (with the Month of the yearly extra), or One-time extra payment (with the Payment number for the one-time extra).
7. Read the headline Total monthly payment and its breakdown, then scroll to the Amortization schedule. Switch it from Yearly to Monthly to see every payment.

How the math works

The loan amount is the price minus the down payment. The principal and interest payment comes from the standard amortization formula: a fixed payment sized so that interest on the shrinking balance plus the leftover principal exactly clears the loan on the last month. Early on, most of each payment is interest; the split flips over time.

The rest is simpler. Property tax is the price times the tax rate, divided by 12; insurance is the yearly premium divided by 12; PMI, when it applies, is the loan times the PMI rate, divided by 12; HOA dues go in as entered.

Extra payments reduce the balance directly, which lowers every future month's interest.

Worked example

Take a $425,000 home with $85,000 down, which is 20%, so there's no PMI. It's a 30-year loan at 6.5%, property tax is 1.0% of the price, insurance is $1,500 a year, there's no HOA, and the first payment is December 2026.

Piece	Math	Monthly
Loan amount	425,000 − 85,000	$340,000 (one time)
Principal & interest	340,000 × 0.0054167 ÷ (1 − 1.0054167^−360)	$2,149.03
Property tax	425,000 × 1.0% ÷ 12	$354.17
Insurance	1,500 ÷ 12	$125.00
PMI	20% down	$0.00
Total monthly payment	2,149.03 + 354.17 + 125.00	$2,628.20

Over 30 years you pay $433,651.26 in interest, more than the loan itself. The first payment is $1,841.67 of interest and only $307.36 of principal. After a year you've paid $21,988.11 in interest and cut the balance by just $3,800.27. Principal doesn't outweigh interest within a payment until payment 233, in April 2046.

Now put $200 in Extra every month. The loan is paid off in 284 months (23 years, 8 months) instead of 360, total interest drops to $326,407.18, and you save $107,244.08 and 76 months. The extra $200 only ever reduces principal, so every dollar cancels interest for the rest of the loan.

Finally, try the same house with only 10% down ($42,500). The loan rises to $382,500, principal and interest to $2,417.66, and PMI at 0.5% adds $159.38 a month for the first 95 months, until the balance reaches 80% of the price. Total monthly payment: $3,056.20, which is $428.00 more than with 20% down. About $15,141 of that over eight years is PMI that builds no equity.

What moves the payment most

The interest rate. On a $340,000 loan, each half-point costs roughly $110 a month: $2,038.47 at 6.0%, $2,149.03 at 6.5%, $2,262.03 at 7.0%, $2,377.33 at 7.5%. Over 360 payments that's tens of thousands of dollars, so shopping two or three lenders is worth an afternoon.

The term. The same $340,000 at 6.5% over 15 years is $2,961.77 in principal and interest, $812.73 a month more, but total interest falls from $433,651.26 to $193,117.71. If that payment doesn't fit, a 30-year loan with extra payments gets you partway there and lets you stop when money is tight.

The down payment. Every $10,000 more you borrow adds $63.21 a month at 6.5% over 30 years. Crossing 20% down also removes PMI, worth $159.38 a month in the example.

Taxes and insurance. They're 18.2% of the example payment, and they rise over time even on a fixed-rate loan. A 2.0% property tax rate instead of 1.0% turns $354.17 a month into $708.33 on this house. Check the county's real rate first.

Reading the extra-payment results

Extra payments do the most good early, when the balance and the monthly interest are largest. A one-time $10,000 payment on the first month of the example loan saves $54,249.56 in interest and 29 months. The same $10,000 at payment 120 saves $25,069.79 and 16 months: still worthwhile, but less than half the effect.

Putting $2,400 in Extra once a year with January as the Month of the yearly extra (a tax refund, say) saves $110,516.69 and 78 months, slightly more than $200 a month does, because the whole lump hits early each year. Use whichever rhythm you'll stick to, and make sure your lender applies the money to principal rather than next month's bill.

When to use the other calculators

Still figuring out your price range? Start with the House Affordability Calculator, which works backward from your income and debts to a maximum price. For a loan you already have, the Amortization Calculator gives the same schedule and extra-payment math without the escrow pieces. The Loan Calculator solves for the rate or term when you know the payment.

What this calculator doesn't do

These are estimates. The lender's loan estimate and closing disclosure govern, and the real tax and insurance figures come from the county and the insurer, not from a percentage you typed. Escrow is adjusted every year, so the total payment changes even though principal and interest don't.

It assumes a fixed-rate loan with no points, no closing costs rolled in and no prepayment penalty. It doesn't model adjustable rates, interest-only periods, FHA or VA mortgage insurance, which works differently from conventional PMI, or your lender's own conditions for dropping PMI.

Frequently asked questions

Estimates for planning only. Your lender, dealer or tax authority sets the real numbers, and rates, fees and rules change. This is not financial, tax or legal advice. Nothing you type here leaves your browser. See the terms of use.