Mortgage Calculator

Monthly principal, interest, taxes, insurance, and PMI for any conventional mortgage — with a full amortization schedule.

How the math works.

M = P × r(1+r)ⁿ / ((1+r)ⁿ - 1) Where: P = loan principal (price minus down payment) r = monthly interest rate (annual rate ÷ 12) n = total number of monthly payments (years × 12) Monthly payment includes: · Principal & Interest (PI) — from the formula above · Property tax (annual ÷ 12) · Homeowner's insurance (annual ÷ 12) · PMI (principal × annual PMI rate ÷ 12) — only if down < 20%

The standard mortgage payment formula — known as the amortization formula — calculates a level monthly payment that fully retires the loan over its term. Each payment is split between interest (on the remaining balance) and principal (reducing what you owe). In the early years, the vast majority of each payment is interest. By the final years, almost all of it is principal.

The formula assumes a fixed interest rate. Adjustable-rate mortgages (ARMs) recalculate when the rate changes. Property tax and insurance are typically held in an escrow account by the lender and paid annually on your behalf, so they are included in the monthly payment even though they are not part of the loan itself.

PMI (Private Mortgage Insurance) protects the lender, not you, when your down payment is below 20%. It typically costs 0.3% to 1.5% of the original loan amount per year, and can be removed once your equity reaches 20%.