Every affordability calculator, including ours, starts with principal and interest. That's the right place to start — but it's not the finish line. The real monthly cost of owning a home includes at least six other categories most first-time buyers never budget for, and finding out about them after closing is a bad way to learn.
The 7 real cost categories
On a $400,000 home, that's $4,000-$8,000/year, or roughly $333-$667/month, that doesn't show up on any mortgage statement. This isn't optional — roofs fail, water heaters die, HVAC systems break. Budget for it monthly so a $6,000 repair isn't a crisis.
Your first-year estimate is a starting point, not a ceiling. Property taxes are reassessed periodically — annually in some states, every few years in others — and tend to rise with home values and local budgets. A house that's affordable at today's tax rate can get materially more expensive in year five.
Rates have risen sharply in many areas due to climate risk — flood, wildfire, and hurricane exposure especially. Get a real quote before you fall in love with a house. Insurance in high-risk zones can add hundreds per month, and in some areas coverage is getting harder to find at all.
Covered in detail in our down payment guide — this runs until you hit roughly 78-80% loan-to-value. It's not permanent, but it's a real monthly cost in the early years of the loan.
If the home has one, HOA fees range widely depending on amenities. They also tend to increase over time and can include special assessments for large repairs — a new roof, a pool, an elevator — that hit all at once, on top of the regular monthly fee.
Homes are often larger than the apartment or rental you're coming from. Expect higher heating/cooling, water, and electric bills — easily $100-$300/month more, depending on square footage and climate.
Real but one-time: movers or moving trucks, furniture for rooms you didn't have before, window treatments, appliances not included in the sale, initial landscaping. The total depends heavily on the gap between your old place and the new one.
Putting it together
Here's what that actually adds up to on a $400,000 home — a realistic range, not a single number, since so much of this depends on your down payment, your credit, and where you live:
| Cost category | Monthly range |
|---|---|
| Mortgage P&I | $1,946 – $2,270 |
| Property tax | $300 – $500 |
| Insurance | $150 – $400+ |
| PMI (if <20% down) | $0 – $150 |
| Maintenance reserve | $333 – $667 |
| HOA (if applicable) | $0 – $300+ |
| Utilities delta | $100 – $300 |
| Realistic total | $2,829 – $4,587 |
That's a wide range, and the mortgage payment alone is often less than half of it. Notice this range is wider than the single tax-and-insurance estimate used in our affordability calculator and salary breakdowns — those use a national-average figure to keep the math comparable across income levels, while this page is showing you the real regional and situational spread. Both are correct; they're answering different questions.
Free Tool
Start with your real number
Get your principal-and-interest baseline first, then layer these costs on top using the ranges above.
Open the Affordability Calculator →Bottom line
Before you commit to a monthly mortgage number, add roughly 25-40% on top for the real cost of owning. If that total doesn't comfortably fit your budget, the house is more expensive than it looks — regardless of what the mortgage calculator alone says. This is exactly why we build the Conservative tier into every affordability number on this site: it's the tier that leaves room for the six categories above, not just the mortgage payment.
Frequently asked questions
How much should I budget for home maintenance each year?
A common rule of thumb is 1-2% of the home's value per year. On a $400,000 home, that's $4,000 to $8,000 annually, or roughly $333 to $667 a month, set aside for repairs and upkeep that don't show up on your mortgage statement.
How much more should I budget beyond my mortgage payment?
A reasonable rule of thumb is 25-40% on top of your principal and interest payment, once you account for property taxes, insurance, maintenance reserves, and — if applicable — PMI, HOA fees, and higher utility bills than you're used to.
Do property taxes stay the same after I buy?
No. Property taxes are reassessed periodically — annually in some states, every few years in others — and tend to rise with home values and local budgets. Your first-year estimate is a starting point, not a fixed number for the life of the loan.
This article is for educational purposes and does not constitute financial advice.