Mortgage tools for the full monthly cost

A toolkit, not a single widget

Smart Mortgage Calculator helps buyers and homeowners see principal, interest, taxes, insurance, PMI, and HOA together — then dig into the scenario that matches their loan. Specialized calculators model refinance break-even, FHA upfront and annual MIP, and ARM intro vs. stress payments. State and county selectors add local tax and insurance context.

Formulas and assumptions are documented on our methodology page. Estimates are educational — confirm pricing with a licensed lender.

How a mortgage payment is built (PITI)

Most people shop a mortgage by the interest rate alone. Lenders and escrow accounts care about the full housing payment — often called PITI: principal, interest, taxes, and insurance. Private mortgage insurance (PMI) or FHA mortgage insurance premiums (MIP), plus HOA dues when they apply, sit on top of that stack. A slightly higher rate in a low-tax county can still beat a lower rate in a high-millage area once escrow is included.

Worked example (illustrative only): on a $400,000 purchase with 20% down, the loan amount is $320,000. At a 6.75% 30-year fixed rate, principal and interest alone are about $2,075 per month. Add a 1.1% effective property-tax rate (~$367/mo), $1,800/year homeowners insurance (~$150/mo), and $0 PMI because the down payment is 20%, and the full housing payment is closer to $2,590 before HOA. Drop the down payment to 5% and PMI appears; switch to FHA and MIP rules replace PMI. Our calculator lets you change those inputs and see the payment update immediately.

Principal and interest are calculated with the standard amortization formula documented on our methodology page. Taxes and insurance defaults can be refined by state and county after you press Go — they are planning estimates, not your exact mill rate or insurer quote.

Why state and county matter

The same loan amount produces different total payments across the United States because property taxes, homeowners insurance, and sometimes HOA norms vary widely. Selecting a state and county and pressing Go loads planning defaults for tax and insurance and, where data is available, FHA and conforming loan-limit context for specialized tools. That does not replace your county assessor, insurance agent, or Loan Estimate — it stops a national average from hiding a local escrow surprise.

After you apply a location, you can expand an amortization schedule and download a PDF of the payment path you just modeled. Change rate, term, or price and the schedule updates with the calculator.

What these tools are — and are not

Smart Mortgage Calculator is an educational product from Michael Hubbard / Axion Integration Services, LLC. We are not a mortgage lender, broker, or creditor, and nothing on this site is a loan offer, pre-approval, or personalized financial advice. Rate averages shown with the calculator come from public Freddie Mac / FRED series when available, with a documented fallback. Loan limits reference published HUD and FHFA figures for 2026 where we cite them.

Always compare official Loan Estimates from licensed lenders on the same day, verify taxes with local authorities, and confirm insurance with carriers that write in your ZIP code. Use our disclaimer and methodology pages if you need the full list of assumptions and limitations.