The number on a mortgage calculator is almost never your real monthly housing cost. The two letters that matter are P&I (principal and interest) versus PITI(principal, interest, taxes, insurance). Here's how they differ, what gets escrowed, and a realistic way to budget for the actual cost of owning a home.
The two acronyms
P&I is the mortgage math everyone learned in algebra: a loan amount + interest rate + term gives you a fixed monthly payment. The mortgage calculatorshows this number. So does Zillow, NerdWallet, and every bank's "estimate your payment" tool.
PITIis what shows up in your bank account. It's P&I plus property taxes plus homeowners insurance, all collected by your lender each month and held in an escrow account. The lender pays the tax and insurance bills on your behalf when they come due — which is why they collect 1/12 of the annual cost each month.
How much bigger is PITI than P&I?
Typically 25–35% larger. On a $300,000 home with a $250,000 loan at 7%:
- P&I: $1,663/month (the calculator's answer)
- Property tax: ~$300–600/month (varies wildly by state — see below)
- Homeowners insurance: ~$120–220/month
- PMI (if down payment under 20%): ~$100–250/month
- Realistic PITI: $2,180–2,730/month
That's 30–65% more than the headline P&I number. Knowing this is the difference between buying a house you can afford and buying a house that drains your savings.
Property tax: the wild variable
Property tax rates differ enormously by state and even by county. As an effective rate (annual tax ÷ home value):
- Hawaii, Alabama: 0.3–0.4%
- Tennessee, Florida, South Carolina: 0.5–0.8%
- Most southern + western states: 0.7–1.2%
- Texas, Wisconsin, Vermont: 1.5–1.9%
- New Jersey, Illinois, New Hampshire: 2.0–2.5%
On a $300,000 home, that's $900/year in Hawaii vs $7,500/year in New Jersey. As a monthly escrow component: $75 vs $625. Always check the tax bill on the listing or county assessor's website before deciding what you can afford.
Insurance and PMI
Homeowners insurance averages $1,400–2,600/year in most states. Florida, Louisiana, and California (wildfire zones) can run $4,000+. The escrowed monthly amount is 1/12 of this.
PMI (private mortgage insurance)kicks in when you put less than 20% down on a conventional loan. It costs 0.5–1.5% of the loan amount per year — so $1,250–3,750/year on a $250,000 loan, escrowed monthly. PMI drops off automatically once your loan balance hits 78% of the original home value, but you can request removal at 80% if you've had a recent appraisal.
FHA loans have similar (often higher) MIP that's harder to remove. Veterans get a VA loan with no PMI and a lower funding fee.
The "true cost of homeownership" rule
Beyond PITI, real-world homeowners spend an additional 1–2% of the home's value annually on maintenance and unexpected repairs. On a $300,000 house, budget another $250–500/month for:
- HVAC tune-ups, water heater replacement
- Appliance failures (fridge, dishwasher, washer/dryer averaging 8–12 year lives)
- Roof repairs, eventual full replacement
- Plumbing, electrical, foundation issues
- Yard, exterior paint, fence, deck stain
- HOA fees (if applicable, $25–500/month additional)
So the real number on a $300K house in a 1% property tax state is something like:
- P&I: $1,663
- + Tax: $250
- + Insurance: $150
- + PMI (if applicable): $150
- + Maintenance reserve: $300
- = $2,513/month true cost
How to figure your number
Run the mortgage calculator to get P&I. Then add:
- Annual property tax ÷ 12 (look up the listing's tax bill)
- Annual insurance estimate ÷ 12 (call an insurer or estimate at 0.5% of home value annually)
- PMI if down payment under 20% (~0.7% × loan amount ÷ 12 as a default)
- Maintenance reserve: 1% of home value ÷ 12
The total is what your housing actually costs. If that number exceeds 28% of your gross income, you're house-poor — even if a lender approves you. Lenders allow up to 36–43% total debt-to-income ratio, but living at the upper end of that range means you're one car repair away from missing a payment.
Other loans that affect your real budget
The lender looks at your total monthly debts when qualifying you. Auto and personal loans both count against your debt-to-income ratio.
Run those numbers too: the car payment calculator for any vehicle financing, and the personal loan calculator for credit card consolidation or other debt. If your existing loans already use 15% of your gross income, your remaining housing budget is tighter than the standard 28% rule suggests.
Quick FAQ
What does PITI mean? Principal, Interest, Taxes, Insurance — the four parts of your monthly mortgage payment when tax/insurance are escrowed.
Can I avoid escrow? Some lenders allow it if you put 20%+ down and have good credit. You then pay tax and insurance bills directly when they come due. Saves a tiny bit of money (you keep the float) but requires discipline to set aside 1/12 each month yourself.
How much house can I afford? Total PITI + maintenance should stay under 28% of gross monthly income. Total monthly debts (housing + cars + loans + credit cards) under 36%. Going higher gets you in the door but stresses your budget.
Run the numbers: use the mortgage calculator for P&I, then add tax + insurance + maintenance manually for true cost. Have a car or other loan? Run those through the car payment and personal loan calculators too.
Not financial advice. This article describes general principles of mortgage and home-buying math for educational purposes. Your actual rates, terms, eligibility, and tax situation depend on your credit, location, lender, and regulations that change. Consult a licensed loan officer or financial advisor before any home-purchase or refinance decision.