What Actually Goes Into a Monthly Mortgage Payment

Most people get a number from a mortgage calculator, budget around it, and then find the real payment is several hundred dollars higher. The calculator was not wrong. It answered a narrower question than the one being asked.

PITI: the four parts

Lenders use the acronym PITI:

• Principal
• Interest
• Taxes
• Insurance

A basic mortgage calculator gives you the first two. Your monthly bill typically includes all four, and often a fifth.

Principal and interest: the loan itself

This is the part that follows the standard amortization formula, the same calculation every lender uses for a fixed rate loan. It depends on three inputs: the amount borrowed, the interest rate, and the term.

The important thing to understand is how the split changes over time. Early in a 30 year loan, the large majority of each payment goes to interest, because interest is charged on the outstanding balance and the balance is near its maximum. As the balance falls, more of each identical payment goes to principal.

This is why paying extra early has an outsized effect. An extra payment in year two removes principal that would otherwise have accrued interest for 28 more years. The same extra payment in year 25 saves comparatively little.

It is also why the total interest over a 30 year term can approach or exceed the amount borrowed, and why a 15 year term costs far less in total interest despite a higher monthly payment. The Mortgage Calculator shows both the monthly figure and the total interest, which is the number worth comparing between terms.

Property taxes

Set by your local jurisdiction as a percentage of assessed value, and they vary dramatically. The same house price produces very different tax bills in different states and counties.

Two things catch buyers out:

• They are usually escrowed. Rather than sending you an annual bill, the lender collects one twelfth each month and pays it on your behalf. It appears as part of your monthly payment.
• They change. Reassessments raise them, and a purchase itself often triggers reassessment. A payment that was affordable at closing can rise without your loan changing at all.

Homeowners insurance

Required by essentially every lender, also usually escrowed. Cost depends on location, construction, coverage, and deductible. In areas exposed to flood, wildfire, or hurricane risk, required additional coverage can be a significant line on its own.

PMI: the fifth component

Private mortgage insurance is typically required when your down payment is under 20 percent of the purchase price. It protects the lender, not you, if you default.

This one is worth attention because it is temporary and removable. As your balance falls relative to the home's value, you can generally request its removal once you reach the relevant equity threshold, and lenders are required to terminate it automatically at a further point. Neither happens on its own if you do not track it, and continuing to pay PMI you no longer owe is a common and entirely avoidable cost.

Note that PMI is not automatically included in most calculator estimates, including ours. If your down payment is under 20 percent, add it yourself.

HOA fees

Not part of PITI and not collected by your lender, but a real monthly cost in condominiums and many planned developments. Lenders count it when assessing what you can afford, so you should too.

Putting a realistic number together

Take the principal and interest figure from a calculator, then add:

1. Annual property tax for the specific property, divided by 12
2. Annual homeowners insurance, divided by 12
3. PMI, if your down payment is under 20 percent
4. HOA fees, if any

The gap between step one and the total is routinely several hundred dollars a month. That gap, not the calculator figure, is what you need to budget against.

Two decisions that matter most

Term length. A shorter term means a higher monthly payment and dramatically less total interest. Compare total interest, not just the monthly figure.

Down payment relative to 20 percent. Crossing that threshold removes PMI entirely, which can change the monthly cost more than a modest difference in interest rate would.

The Mortgage Calculator covers principal and interest and total interest over the term. For the full picture, add the escrowed items above. Our Calculator Methodology page sets out exactly what the calculation includes and what it does not.

The bottom line

Principal and interest is the loan. Taxes, insurance, and PMI are the cost of owning the house the loan bought. Budget for all of them, and the number at closing will not be a surprise.