Mortgage Calculator

How this calculator works

The monthly principal-and-interest payment comes from the standard amortization formula: M = P · r(1+r)n / ((1+r)n − 1), where P is the loan amount, r is the monthly interest rate (APR / 12), and n is the total number of payments (years × 12). This is the same formula every US mortgage lender uses.

What is PITI?

PITI stands for Principal, Interest, Taxes, and Insurance — the four components of a typical monthly mortgage payment when your lender collects taxes and insurance in escrow. Property tax and homeowners insurance are annualized amounts divided by 12 and added to your monthly principal-and-interest payment. Most lenders qualify you against your total PITI, not just P&I.

What is PMI?

Private Mortgage Insurance protects the lender when you borrow more than 80% of the home's value (i.e., you put less than 20% down). PMI is typically 0.3% to 1.5% of the original loan amount per year, paid monthly. Federal law generally requires lenders to cancel PMI automatically once your loan balance reaches 78% of the original home price, or on request at 80%. This calculator drops PMI once the amortized balance crosses the 80% threshold.

Do extra payments really help?

On a 30-year fixed mortgage at typical rates, an extra $100–$200 per month applied to principal can shave several years off the term and tens of thousands off total interest — because interest is charged on the remaining balance, so faster principal reduction compounds. This calculator shows exactly how many months you save and how much interest disappears at whatever extra amount you enter.

What this calculator does not include

HOA fees, closing costs, points, adjustable-rate resets, prepayment penalties, escrow shortages, and lender-specific fees are not modeled. The output is a clean baseline; a real Loan Estimate from a lender will differ. This is a planning tool, not a quote.