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Mortgage Calculator with Amortization

Estimate your monthly payment and how much of the loan goes to interest.

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Payment (P&I)

Monthly all-in

Total interest

Total of payments
Adjust the inputs above to see the breakdown.

The chart shows lifetime principal vs. interest on the financed amount. Estimates only — not financial advice.

How to Use This Calculator

  1. Enter the home price you are considering.
  2. Set your down payment as a percentage. The helper text shows the dollar amount and the resulting loan size.
  3. Enter the interest rate your lender quoted and pick a loan term.
  4. Add property tax, insurance and HOA if you want a full "all-in" monthly figure.
  5. Review the results. "Payment (P&I)" is principal and interest only; "Monthly all-in" adds taxes, insurance and HOA. The doughnut chart shows how much of every dollar you repay over the life of the loan is principal versus interest.

The Formula Explained

The monthly principal-and-interest payment comes from the standard amortizing-loan formula:

M = L × [ i (1 + i)ⁿ ] ÷ [ (1 + i)ⁿ − 1 ]
  • M — monthly principal & interest payment
  • L — loan amount = home price − down payment
  • i — monthly interest rate = annual rate ÷ 12
  • n — number of payments = term in years × 12

Total interest is (M × n) − L. Property tax is applied as a percentage of the home price and divided by 12; insurance and HOA are added directly to the monthly figure.

Frequently Asked Questions

How much of a down payment do I need?

A 20% down payment lets you avoid private mortgage insurance (PMI) on a conventional loan. Conventional loans can go as low as 3–5% down, and FHA loans as low as 3.5%, but a smaller down payment means a larger loan balance, an added PMI premium, and more interest over the life of the loan.

What is included in my monthly mortgage payment?

Lenders call it PITI: Principal, Interest, property Taxes, and homeowners Insurance — the last two often collected in an escrow account. HOA dues and, if you put down less than 20%, PMI are on top of that. This calculator breaks out principal & interest and lets you add tax, insurance and HOA lines.

Should I choose a 15-year or 30-year mortgage?

A 15-year loan has a higher monthly payment but a lower rate and dramatically less total interest. A 30-year loan keeps the required payment low and flexible but costs far more over time. A common middle path is a 30-year loan with extra principal payments whenever your budget allows.

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