Most first-time buyers shop for a home based on one number: the monthly payment quoted at a given interest rate. What they don't realize until closing — or worse, until the first mortgage statement arrives — is that number was only part of the picture. Your true monthly housing cost includes four components, and ignoring the other three is one of the most common reasons new homeowners feel stretched thin in year one.
The industry calls it PITI: Principal, Interest, Taxes, and Insurance. Understanding each one before you commit changes how you shop, how much you put down, and which loan term actually makes sense for your situation.
What You're Actually Paying Each Month
Principal is the portion of your payment that reduces your loan balance. In the early years of a 30-year mortgage, this is a surprisingly small slice — on a $400,000 loan at 7%, your first payment sends roughly $467 to principal and $2,333 to interest. That ratio flips gradually over the life of the loan, but it takes about 19 years before more than half of each payment goes to principal.
Interest is the cost of borrowing. On that same $400,000 loan at 7% over 30 years, you'll pay approximately $558,000 in total interest — more than the original loan amount. Drop the rate to 6% and that figure falls to roughly $464,000. A single percentage point is nearly $100,000 over the life of the loan, which is why rate shopping across even three lenders before committing is worth several hours of your time.
Taxes are property taxes collected monthly by your lender and held in escrow until the annual bill is due. The national average effective property tax rate is around 1.1%, but it varies enormously by state — New Jersey averages over 2%, while Hawaii sits below 0.3%. On a $400,000 home at 1.1%, that's roughly $367/month added to your payment before you've touched insurance or PMI.
Insurance is homeowners insurance, also typically escrowed. Budget $100–$200/month for most properties, more in high-risk areas for flood, wind, or wildfire. This isn't optional — lenders require it.
| Component | Example ($400K home, 7%, 30yr) | Notes |
|---|---|---|
| Principal + Interest | ~$2,661/month | Fixed for loan term |
| Property tax | ~$367/month | Varies heavily by state |
| Homeowners insurance | ~$150/month | Varies by location/property |
| PMI (if <20% down) | ~$133–$400/month | Drops when you hit 20% equity |
| True monthly cost | ~$3,311+/month | Before HOA fees |
The PMI Trap — And How to Get Out of It
Private Mortgage Insurance is required by most lenders when your down payment is below 20%. It protects the lender, not you, and costs roughly 0.5%–1.5% of your loan amount annually. On a $400,000 loan that's $167–$500 every month — real money for coverage that provides you no direct benefit.
The good news: PMI isn't permanent. By law, lenders must cancel it automatically when your loan balance reaches 78% of the original purchase price through scheduled payments. You can request cancellation earlier once you've paid down to 80% — or reach that threshold faster by making extra principal payments. A $200/month extra payment on a $400,000 mortgage can eliminate PMI years ahead of schedule, and the monthly savings once it drops off are immediate.
One number worth running: how many months of PMI payments equal your cost of putting down an extra 5%? If saving an additional $20,000 for a full 20% down payment would take you two years but you'd pay $300/month in PMI for those two years, you're paying $7,200 in PMI while waiting — a clear case where buying sooner with PMI and eliminating it through extra payments can win.
15-Year vs. 30-Year: The Real Trade-Off
The 30-year mortgage wins on monthly cash flow. The 15-year mortgage wins on total cost. The gap is larger than most people expect.
On a $400,000 loan at current rates, a 30-year term runs roughly $2,661/month in principal and interest. A 15-year term runs roughly $3,592/month — about $931 more per month. But the total interest paid over the 15-year loan is less than a third of what the 30-year costs. You'd pay roughly $246,000 in total interest on the 15-year versus $558,000 on the 30-year.
The question isn't which is mathematically better — the 15-year wins that contest easily. The question is what you do with the $931/month difference if you choose the 30-year. If it goes into a retirement account earning 7% annually, the 30-year loan with disciplined investing can actually outperform the 15-year paydown. If the $931 disappears into lifestyle spending, the 15-year forced savings wins.
Use the mortgage calculator to run your specific numbers — home price, down payment, and rate — and see the full PITI breakdown including PMI if applicable. The difference between what you expect to pay and what you'll actually pay each month is the number worth knowing before you make an offer.