Understanding Mortgage Payments: Principal, Interest, Taxes and Insurance
Last updated 2026-10-20
Anatomy of a payment (PITI)
Most monthly mortgage payments bundle four parts: Principal (repayment of the loan), Interest, Taxes (property tax, often held in escrow) and Insurance (homeowner's insurance, and mortgage insurance if your down payment was under 20%). Lenders call the bundle PITI.
Our Mortgage Calculator separates principal-and-interest from tax, insurance and HOA dues so you can see each part clearly.
Why early payments are mostly interest
Amortization charges interest on the outstanding balance. At the start the balance is at its largest, so most of each payment is interest; as the balance falls, the interest share shrinks and the principal share grows. On a $300,000 loan at 6% over 30 years, the first payment is $1,798.65 — of which $1,500 is interest and only $298.65 is principal.
That is also why extra principal payments early in the loan save the most interest: they shrink the balance that every future interest charge is based on.
The three levers
Rate: half a percentage point on $300,000 over 30 years changes the payment by roughly $100 a month and the lifetime interest by tens of thousands. Term: 15 years instead of 30 raises the payment but cuts total interest by more than half in this example. Down payment: a larger down payment reduces the loan, the payment, and may remove mortgage insurance.
The APR Calculator helps compare two lender quotes including fees, and the Debt-to-Income Calculator shows whether the payment fits lender guidelines.