Most mortgage calculators show you a clean monthly payment — and then you close on the house and discover the real number is hundreds of dollars higher. The gap is everything a basic calculator leaves out: property taxes, homeowners insurance, and sometimes mortgage insurance. Lenders bundle these into a single acronym, PITI, and understanding it is the difference between a budget that works and one that breaks in month one.
What PITI Actually Means
PITI stands for the four components of a typical mortgage payment. The first two are the loan itself; the second two are the costs of owning the property the loan is attached to.
- Principal — the portion of each payment that reduces what you owe.
- Interest — the lender's charge for borrowing, highest in the early years.
- Taxes — property taxes assessed by your local government, often collected monthly via escrow.
- Insurance — homeowners insurance, plus mortgage insurance (PMI) if your down payment is under 20%.
A basic loan calculator gives you only the P and the I. Lenders, however, qualify you on the full PITI, because that's the true monthly obligation. This is why the payment your lender quotes is almost always higher than the one a simple calculator shows.
Principal and Interest: The Foundation
Principal and interest are calculated using the standard amortization formula, where the monthly payment M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]. Here P is the amount borrowed, r is the monthly interest rate, and n is the number of payments. This produces a fixed payment that stays the same for the life of a fixed-rate loan, even though the split between principal and interest shifts over time.
Early in the loan, most of that $2,528 is interest. Over time the balance falls, the interest portion shrinks, and more goes to principal — the amortization process. You can see this split month by month in any full amortization schedule.
Taxes: The Cost That Never Goes Away
Property taxes are charged by your county or municipality, typically as a percentage of your home's assessed value — anywhere from about 0.3% to over 2% per year depending on where you live. On a $400,000 home at a 1.2% rate, that's $4,800 a year, or $400 a month, usually collected into an escrow account and paid on your behalf.
Crucially, property taxes never disappear. Even after you've paid off the mortgage entirely, you keep paying taxes for as long as you own the home — and they tend to rise over time as assessed values increase. This is the cost that catches new homeowners off guard, because there's no version of ownership where it stops.
Insurance: Two Different Kinds
There are two distinct insurance costs hiding in PITI, and people frequently confuse them.
Homeowners Insurance
This protects your property against fire, theft, storms, and liability. Lenders require it, and it typically runs $1,000–$3,000 per year depending on your home's value, location, and risk factors. Like taxes, it's usually escrowed into your monthly payment.
Private Mortgage Insurance (PMI)
PMI is different: it protects the lender, not you, and it's required when your down payment is less than 20% of the purchase price. It usually costs 0.5%–1.5% of the loan amount per year. The good news is that PMI is temporary — once you build 20% equity, you can request its removal, which can cut your payment by a hundred dollars or more a month.
Putting It All Together: A Full PITI Example
Let's build the real monthly cost of a $400,000 home with a 10% down payment ($40,000 down, $360,000 financed) at 6.5% over 30 years.
- 1Principal & Interest on $360,000: ≈ $2,275/month.
- 2Property taxes at 1.2% of $400,000: $4,800/year ≈ $400/month.
- 3Homeowners insurance at $1,800/year: ≈ $150/month.
- 4PMI at ~0.8% of $360,000 (under 20% down): ≈ $240/month.
- 5Total PITI: 2,275 + 400 + 150 + 240 ≈ $3,065/month.
The basic calculator said $2,275. The real number is over $3,065 — about 35% higher. Budgeting on the P&I figure alone would have left this buyer $790 short every single month. That's the entire reason PITI exists as a concept.
The Costs Even PITI Leaves Out
- HOA or condo fees — can add $200–$700+ per month in many communities.
- Maintenance and repairs — a common rule of thumb is 1% of the home's value per year.
- Utilities — often higher than in a rental, especially in a larger home.
- Closing costs — typically 2%–5% of the loan, paid upfront at purchase.
A useful guideline is the 28/36 rule: aim to keep PITI under 28% of your gross monthly income, and total debt payments under 36%. Many lenders use these ratios to decide how much you qualify for — but qualifying for a payment and comfortably affording it are not the same thing.
Fixed-Rate vs Adjustable-Rate Mortgages
The 'I' in PITI behaves very differently depending on your loan type. A fixed-rate mortgage locks your interest rate — and thus your principal-and-interest portion — for the entire term, usually 15 or 30 years. The taxes and insurance can still drift upward, but the core loan payment is rock-solid and predictable.
An adjustable-rate mortgage (ARM) starts with a fixed rate for an initial period — say 5, 7, or 10 years — and then adjusts periodically based on a market index. ARMs typically offer a lower starting rate, which can be tempting, but the payment can rise significantly once the fixed period ends. A common mistake is buying the maximum house an ARM's low introductory payment allows, then being unable to afford the payment after it adjusts.
- Fixed-rate: predictable for the whole term, ideal if you'll stay put and want certainty.
- ARM: lower early payments, but real interest-rate risk later — best only if you'll likely sell or refinance before it adjusts.
- Always check an ARM's adjustment caps and the fully-indexed rate, not just the teaser rate.
How Much House Can You Actually Afford?
Lenders will often approve you for more than you should comfortably spend, because their approval is based on gross income and a few debt ratios — not on your real life, with its childcare, car payments, savings goals, and the occasional emergency. The pre-approval number is a ceiling, not a target.
- 1Start from your take-home (net) pay, not gross — that's the money you actually live on.
- 2Apply the 28% rule to gross income to get a PITI ceiling, then sanity-check it against your real budget.
- 3Add the costs PITI ignores: maintenance (~1% of value per year), HOA fees, higher utilities, and commuting.
- 4Leave room for savings and an emergency fund — a house that consumes every spare dollar is a liability, not just an asset.
A practical test: take the full estimated PITI (plus maintenance and HOA) and 'practice' paying it for a few months before you buy — set aside the difference between that figure and your current rent. If it feels comfortable, you're ready. If it feels tight, the calculator just saved you from a stressful purchase.
Frequently Asked Questions
Why is my lender's payment higher than the calculator's?
Because the calculator likely shows only principal and interest, while your lender includes escrowed taxes and insurance. Always ask for the full PITI estimate so you're comparing the real monthly obligation.
Can I get rid of PMI?
Yes. Once you reach 20% equity — through payments, appreciation, or a combination — you can request PMI removal. By law it must automatically terminate at 22% equity on most loans. Removing it can meaningfully lower your payment.
Do taxes and insurance ever change?
Yes, and this is important: even with a fixed-rate mortgage, your total payment can rise over time because property taxes and insurance premiums tend to increase. Your principal and interest stay fixed, but the T and I in PITI can drift upward, so your escrow payment is periodically adjusted.
A mortgage payment is really four payments wearing one number. Principal and interest are the loan; taxes and insurance are the cost of the property itself — and unlike the loan, taxes never end. Before you fall in love with a monthly figure, build out the full PITI (plus maintenance and HOA) so you know the true cost of ownership. Start with the principal and interest in the loan and mortgage calculator, then layer your local tax rate and insurance estimates on top.