True Monthly Cost Calculator

Why your mortgage payment is only 65% of the story.

A standard mortgage calculator answers a narrow question: "what's the principal and interest on this loan?" That figure is real, but it's never what arrives in your bank statement. Once property taxes, insurance, HOA dues, PMI, and maintenance are layered in, the actual monthly cost of owning a home typically runs 35% to 60% higher than the mortgage payment alone.

For a $425,000 home with 20% down at 6.75%, that gap is roughly $1,300 per month. Over a five-year hold, that's $78,000 in costs that never appear on a typical mortgage estimate. This calculator exists to put those costs back where they belong: in the number you compare against your budget.

Principal & interest

This is the loan repayment portion of your payment — the part that goes to the lender. It's calculated using a fixed-rate amortization formula and stays the same every month for the life of a fixed-rate loan. In the first years, most of it is interest; toward the end, most is principal. On the example above, P&I is $2,205/month.

Property tax

Local governments tax real property at a percentage of assessed value, typically billed annually or semi-annually but escrowed monthly with most mortgages. Effective rates vary wildly — under 0.5% in Hawaii to over 2% in parts of Texas, New Jersey, and Illinois. Most lenders escrow tax and insurance into your monthly payment, so the same loan in two different counties can have very different monthly totals.

Homeowners insurance

A standard HO-3 policy covers the structure, your belongings, and liability. Premiums depend on the home's replacement cost, the construction type, the local risk profile (hurricane, hail, wildfire, flood), and your claims history. Coastal Florida and wildfire-exposed California carry premiums multiples of what a low-risk Midwest home pays — and rates have been climbing fast in disaster-exposed markets.

PMI (Private Mortgage Insurance)

PMI applies to conventional loans with less than 20% down. It protects the lender, not you, and typically costs 0.3%–1.5% of the loan per year — we default to 0.75% in this calculator. PMI drops off automatically once your loan-to-value ratio reaches 78%, but until then it can add $100–$300 per month on a typical home. FHA loans have a parallel system (MIP) with different rules; see our FHA vs Conventional Calculator.

HOA dues

Homeowners associations collect monthly dues to maintain shared amenities and enforce community standards. Ranges are enormous — a suburban subdivision might charge $35/month while a Miami high-rise condo charges $1,200. Special assessments for major repairs (roofs, elevators, structural work) can land at any time. Always read the HOA's reserve study before buying into a building.

Maintenance reserve

This is the single most underestimated line item in homeownership. Roofs need replacing. HVAC systems fail. Water heaters die. Gutters clog. Termites arrive. The widely cited rule of thumb is 1% of home value per year set aside for maintenance — slightly more for older homes or harsh climates. For a $425,000 home, that's about $354/month. You won't spend it every month, but over 10 years you'll spend close to it on average.

Why the gap matters most

The gap between mortgage payment and true cost is largest in three situations: low down payments (PMI is added), high property-tax states (Texas, NJ, IL, NH), and homes with HOA dues. In any of these, the difference between "what the calculator says" and "what your account shows" can exceed $1,500/month. A pre-approval that says you can "afford" $3,000 a month in mortgage payments often means you're actually committing to closer to $4,500 in housing cost. That's the gap the affordability assessment misses.