Mortgage Calculator

How to use this calculator

1. Enter the home price and your down payment — the percentage down updates automatically.
2. Set the loan term (usually 15 or 30 years) and the interest rate.
3. Press Calculate to see your estimated monthly payment and its breakdown; after the first result, any edit updates it live.
4. Expand Taxes, insurance & fees to add property tax, home insurance, HOA dues and PMI for your true monthly cost.
5. Expand Increases & extra payments if you want to model yearly cost rises, extra payments, or a biweekly schedule. Anything you leave blank is simply ignored.

Understanding your payment breakdown

A mortgage payment is more than principal and interest — lenders call the full figure PITI (principal, interest, taxes, insurance). The colored bar splits your total into five parts:

• Principal & interest — repaying the loan plus the cost of borrowing.
• Property tax — set by your local government, usually escrowed monthly.
• Home insurance — protects the property; typically required by lenders.
• PMI — applies when you put down less than 20%, and drops off automatically.
• HOA — dues for condos or planned communities, if any.

The amortization formula

The principal-and-interest portion uses the fixed-rate amortization formula:

M = P · r · (1 + r)ⁿ / ((1 + r)ⁿ − 1)

• M — the monthly principal-and-interest payment
• P — the loan amount (home price minus down payment)
• r — the monthly interest rate (annual rate ÷ 12)
• n — the total number of payments (years × 12)

Early payments are mostly interest; as the balance falls, more of each payment goes to principal. The yearly schedule on this page shows that shift and your remaining balance at the end of every year.

A worked example

Buy a $400,000 home with 20% down ($80,000), leaving a $320,000 loan at 6.5% over 30 years. The monthly rate is 0.065 ÷ 12 and there are 360 payments, giving a principal-and-interest payment of $2,022.62 a month. Over the full term you repay $728,142 — $408,142 of it interest.

Those figures are calculated by this page's own mortgage engine, not typed in by hand. Enter your own numbers above to replace them — the calculator starts empty so the result you see is always yours.

15-year vs. 30-year

A shorter term means a higher monthly payment but dramatically less interest, because the balance is repaid far faster. On that same $288,000 loan at 6.5%:

Term	Monthly P&I	Total interest
30-year	$1,820	~$367,300
15-year	$2,510	~$163,700

The 15-year costs about $690 more a month but saves roughly $200,000 in interest — the classic trade-off between monthly cash flow and lifetime cost.

How much house can you afford?

A common guideline is the 28/36 rule: keep housing costs (PITI) under 28% of gross monthly income, and all debt payments under 36%. On a $6,000 monthly income that is roughly $1,680 for housing. Lenders also weigh your credit score, down payment and existing debts, so treat any figure here as a planning estimate, not an approval.

Modelling extra payments and rising costs

The four core fields answer "what will this cost me a month". The optional panel answers the follow-up questions, and every field in it is blank by default — fill in only what you want modelled, and the result grows a section reporting it.

Extra payments go straight to principal, so they save interest on every month that would have followed. You can set an amount paid every month, an amount paid once a year, and one-off lump sums — a bonus, a tax refund — each dated to the month it lands. The result then shows the extra principal paid, the interest saved, the time saved and the new payoff. Your quoted monthly payment does not change: extra is voluntary, not owed.

Annual increases apply to property tax, home insurance, HOA dues and other costs. Year one always uses the amount exactly as entered, so the headline payment stays the figure your lender quoted; from year two each cost compounds at its own rate. The result adds a total for each cost across the life of the loan and a total cost of ownership.

Biweekly payback compares your loan against paying half the monthly principal and interest every fortnight. Twenty-six half-payments is thirteen monthly payments a year, so the thirteenth acts as an extra payment and the loan closes years early.

Tips to lower your mortgage cost

• Increase your down payment to 20% to eliminate PMI.
• Compare a 15-year term: a higher monthly payment but far less total interest.
• Even a 0.25% lower rate can save thousands over the life of the loan — shop lenders.
• Making one extra payment a year shortens a 30-year loan by several years.

This tool provides estimates for planning and does not constitute a loan offer or financial advice. Your actual rate, taxes and insurance will depend on your lender, location and credit profile. To see the full split of interest and principal over time, use the amortization calculator.