Mortgage calculator

A mortgage payment is more than principal and interest - taxes, insurance, HOA dues, and PMI decide what actually leaves your account each month. This calculator shows the full PITI picture, the total interest over the life of the loan, your payoff date, a year-by-year amortization schedule you can expand to months, and what an extra monthly payment would save.

Home price ($)

Down payment ($)

Dollar and percent stay in sync.

Down payment (%)

Loan term

Custom term (years)

Used only when term is "Custom".

Interest rate (%)

Property tax ($/year, optional)

Home insurance ($/year, optional)

HOA dues ($/month, optional)

PMI rate (%/year of loan, optional)

Typically ~0.3–1.5% when down payment is under 20%; drops off near 20% equity.

Extra monthly payment ($, optional)

This calculator needs JavaScript. The formula it uses: M = P·r·(1+r)ⁿ ÷ ((1+r)ⁿ − 1), where P is the loan amount, r the monthly rate, and n the number of months - then taxes, insurance, HOA, and PMI are added to get the real monthly cost.

How the math works

Principal & interest come from the standard amortization formula M = P·r·(1+r)ⁿ ÷ ((1+r)ⁿ − 1). Early payments are mostly interest; the balance tips toward principal over time - expand the schedule above and watch year 1 versus year 20. PMI is modeled until the balance reaches 80% of the home price, which is when lenders typically allow removal. The extra-payment comparison reruns the whole schedule, which is why small extras produce outsized interest savings: every early dollar of principal stops compounding against you for the rest of the loan.

Start with what credit score you need to buy a house and how much to budget for closing costs. If PMI is in your numbers, can you remove PMI early explains the removal rules, and 15-year vs 30-year mortgages covers the term trade-off this calculator makes visible.

The formula this calculator uses

loan          = price - deposit
r             = annual rate / 100 / 12
n             = years * 12
P and I       = loan * r * (1+r)^n / ((1+r)^n - 1)
monthly total = P and I + tax/12 + insurance/12 + HOA + mortgage insurance
mortgage insurance applies only while loan / price is above 80%

What it assumes without asking

Interest compounds monthly and the rate never changes, which is true of a fixed-rate loan and not of an adjustable one
Property tax and insurance are entered as annual figures and divided by twelve
Mortgage insurance is charged at the rate you enter, on the loan amount, and stops being applied at a deposit of 20%
Nothing is escrowed, prepaid or prorated at closing

One example, computed in full: $375,000 at 6.00% over 30 years

Line	Value
Purchase price	$375,000
Deposit, 20%	$75,000
Loan amount	$300,000
Monthly principal and interest	$1,798.65
Interest in month 1	$1,500.00
Principal in month 1	$298.65
Interest in month 360	$8.95
Total repaid over 30 years	$647,514.57
Total interest	$347,514.57
Interest as a share of the loan	115.8%

What this calculator does not model

Closing costs, which are paid at purchase and are not part of the payment
Any rate that changes, so an adjustable-rate loan is out of scope
Tax and insurance rises, which are near certain over 30 years
Whether a lender will actually approve the loan, which turns on income, debts and credit rather than on this arithmetic

The guide behind this tool

A number on its own does not tell you what to do with it. Read what debt-to-income ratio is for the test a lender applies to the payment above, and how much to budget for closing costs for the money this calculator deliberately leaves out.

Sources & further reading

This tool is a general educational estimate, not financial advice or a loan offer. Real quotes vary by credit, location, points, and fees. See our disclaimer.