What’s included in this payment
A mortgage payment is rarely just principal and interest. This calculator rolls in the four costs that typically show up on a real monthly bill: principal and interest on the loan itself, property tax, home insurance, and (if your down payment is under 20%) private mortgage insurance (PMI). An optional HOA fee is added on top for homes where one applies. Adding these separately, rather than folding them into one number, makes it clear which parts are fixed by the loan and which depend on where you live and how you insure the home.
How PMI is calculated, and when it goes away
PMI is charged as a percentage of the loan amount per year, split into monthly installments, and it only applies while your equity is thin. This calculator checks your down payment against the 20% threshold to decide whether PMI applies at all, then walks the amortization schedule to find the month your balance is projected to drop to 78% of the original home price: the point federal law requires automatic cancellation for a typical conventional loan. That’s an estimate based on the scheduled payoff; paying extra toward principal would get you there sooner, and a change in your home’s market value doesn’t affect this scheduled figure.
Why property tax and insurance are shown as their own lines
Property tax and insurance don’t depend on your loan terms at all: they depend on your home’s assessed value and where you live. Keeping them as separate inputs (rather than baking in an assumption) means you can swap in your actual county tax rate and your actual insurance quote once you have them, and immediately see how the total payment moves. Many first-time buyers are surprised that these two lines alone can add several hundred dollars a month on top of principal and interest.
Reading the yearly table
The table below the summary numbers covers principal and interest only (the same amortization math as a plain loan calculator) since property tax, insurance, PMI and HOA don’t amortize; they’re recalculated fresh each year at roughly the same rate. Each row sums twelve months into one line: how much went to principal, how much to interest, and what’s left owed. The split shifts from mostly-interest early on to mostly-principal later, which is normal for every fixed-rate loan.