How Much House Can You Afford? The 28/36 Rule and What It Leaves Out
2026-07-31
Type any income into an online mortgage calculator and it will happily tell you a home price. Most of those calculators quietly ignore property tax, insurance, HOA dues, PMI, and maintenance — the costs that turn an affordable-looking loan payment into an unaffordable total housing bill.
The 28/36 Rule Lenders Actually Use
The 28/36 rule is a long-standing lending guideline, not a law: your total housing costs shouldn’t exceed roughly 28% of gross monthly income (the front-end ratio), and your housing costs plus all other debts shouldn’t exceed roughly 36% (the back-end ratio, equivalent to overall DTI). It’s a starting guideline — many conventional lenders now approve back-end ratios up to 45% or higher with strong credit and reserves — but 28/36 remains a useful conservative anchor for a household’s own budget, independent of what a lender might technically approve.
What Counts in Your Housing Payment (PITI, Not Just P&I)
A mortgage calculator that only shows principal and interest (P&I) is showing you an incomplete number. The full monthly housing cost — PITI — adds property Taxes and Insurance, plus HOA dues and PMI where applicable. Property tax and insurance alone can add hundreds of dollars a month depending on location, and they’re exactly the costs a bare-bones P&I calculator omits.
Worked Example: A $95,000 Household Income
A household earning $8,000 gross a month ($96,000/year) with $400 in other debt and a 36% back-end target has a maximum modeled total housing payment of roughly $2,480 a month ($8,000 × 36% − $400). That $2,480 has to cover principal, interest, taxes, insurance, HOA, and PMI combined — not just the loan payment — which is why the resulting affordable home price is often lower than a P&I-only calculator suggests for the same income.
Down Payment: the 20% Myth and What PMI Really Costs
Putting down less than 20% on a conventional loan generally triggers private mortgage insurance (PMI), an added monthly cost that protects the lender, not the buyer. Under the Homeowners Protection Act, PMI must be automatically terminated once your balance is scheduled to reach 78% of the original home value (as long as you’re current on payments), and you can request cancellation earlier once you reach 20% equity (80% loan-to-value) based on the original value. Twenty percent down is a common target, not a legal requirement — plenty of buyers put down less and pay PMI temporarily instead.
Property Tax and Insurance Vary More Than the Rate Does
A national “average” property tax rate is nearly useless for budgeting, because rates vary enormously by county and even by school district. The same is true of homeowners insurance, which varies by state, coverage level, and increasingly by wildfire, flood, or hurricane risk. Use your target area’s actual mill rate or a recent comparable listing’s tax bill — not a national estimate — before finalizing an affordability number.
How a 1-Point Rate Change Moves Your Max Price
Because a higher rate raises the monthly principal-and-interest cost of every dollar borrowed, a one-percentage-point rate increase reduces the loan amount you can support at the same monthly payment — often by roughly 10%, though the exact impact depends on your term and starting rate. Run your affordability number at your quoted rate plus one point as a stress test before assuming a rate lock is guaranteed through closing.
Closing Costs Are Cash, Not Part of the Monthly Payment
Closing costs — typically covering lender fees, title insurance, appraisal, and prepaid escrow — are a separate cash requirement due at closing, on top of your down payment, and are not part of your ongoing monthly PITI. Reserving cash after closing for moving costs and an emergency fund is separate again from the down payment itself; treating all available cash as the down payment leaves nothing for the costs that follow immediately after you get the keys.
Where These Numbers Come From
- Consumer Financial Protection Bureau — “When can I remove private mortgage insurance (PMI) from my loan?”, reviewed 2026-07-31, for the 78% automatic-termination and 80% borrower-request thresholds under the Homeowners Protection Act.
- The 28% front-end / 36% back-end guideline is a widely used industry rule of thumb, not a statutory limit; actual lender approvals commonly extend beyond it with compensating factors — see the companion DTI article for current FHA/VA/conventional program limits.
- Property tax and insurance figures are inherently local; confirm your target area’s rate with the county assessor’s office or a current listing’s tax bill rather than a national average.
This guide is general education, not individualized financial or lending advice, and does not predict loan approval for any specific application. Do not enter identifying information into a shareable URL.
Frequently Asked Questions
Why is this result lower than a simple mortgage calculator’s number?
Because it includes property tax, insurance, HOA, PMI, and maintenance inside your monthly cap, rather than showing only principal and interest.
Are closing costs part of the monthly payment?
No — they’re a separate cash requirement at closing, on top of the down payment.
Does a result under the 28/36 guideline guarantee loan approval?
No — approval also depends on credit history, assets, appraisal, and program-specific rules.
Why include maintenance if it’s not a fixed bill?
Ownership involves irregular repairs a loan payment doesn’t show; budgeting a maintenance reserve avoids treating a predictable long-run cost as a surprise.
Can I set a lower personal budget than the 36% guideline?
Yes — using a lower personal cap than a lender’s maximum approval is a common way to keep a comfortable cash-flow margin.
Use the calculator
Open the related calculator, reproduce the $8,000-income example above, and then enter your own income, debts, and local tax and insurance estimates.