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The 28/36 Rule, Explained

Lenders do not guess how much you can borrow — they measure your debt-to-income ratio, or DTI. The classic guideline is the 28/36 rule. The front-end ratio says your total housing payment — principal and interest, property taxes, homeowners insurance, and HOA fees — should stay under 28% of your gross monthly income. The back-end ratio says that housing payment plus every other monthly debt obligation should stay under 36%. You must pass both tests, so whichever produces the smaller housing budget is your real limit.

Why do lenders use it? Decades of default data show that borrowers whose payments stay inside these bands are far less likely to fall behind. The rule protects the lender, but it also quietly protects you from a payment that looks affordable on a spreadsheet and suffocating in real life.

What Counts as "Monthly Debts" — and What Doesn't

The back-end ratio counts recurring obligations with a required minimum payment: car loans, student loans, credit card minimum payments, personal loans, child support, and alimony. It does not count the rest of your life — utilities, groceries, gas, phone plans, streaming subscriptions, gym memberships, or insurance other than homeowners. That distinction matters in both directions: ignoring your $400 car payment inflates what you "qualify" for, while counting your grocery bill would unfairly shrink it.

Why the Number Is a Ceiling, Not a Target

The result above is the maximum a lender might approve — not a recommendation for how much to spend. Three reasons to shop below it. First, lenders use your gross income, but you live on your take-home pay; a payment at 28% of gross is often 35% or more of what actually hits your account. Second, owning a home brings costs this calculator cannot see: maintenance, repairs, and the water heater that dies in year two. A common guideline is budgeting 1% of the home's value per year for upkeep. Third, a maximum-size payment leaves no margin for the rest of your life — retirement savings, travel, kids, or simply sleeping well when income dips. Many financial planners suggest keeping housing under 25% of take-home pay instead of 28% of gross. Use this ceiling to know your limit, then choose a price that leaves you room to live.

Frequently Asked Questions

What is the 28/36 rule?

A common lender guideline: your total housing payment (principal, interest, taxes, insurance, and HOA) should not exceed 28% of your gross monthly income, and your housing payment plus all other monthly debt payments should not exceed 36%. The lower of the two limits determines the maximum housing payment you qualify for.

What counts as monthly debt in the 36% rule?

Recurring obligations with required minimum payments: car loans, student loans, credit card minimums, personal loans, child support, and alimony. Everyday living costs — utilities, groceries, gas, streaming subscriptions, insurance other than homeowners — do not count, even though they affect your real budget.

How much house can I afford on a $90,000 salary?

It depends on your debts and down payment. Example: $90,000 income, $500 of monthly debt payments, $60,000 down, a 6.5% 30-year loan, 1.1% property tax, and $1,500 annual insurance supports a home price of roughly $325,000 — the 28% front-end rule caps the housing payment at $2,100 per month. Try your own numbers above.

Do lenders use gross income or take-home pay for DTI?

Gross income — your pay before taxes and other deductions. That is one reason the 28/36 numbers can feel generous: your actual take-home pay is lower, so a housing payment at the 28% ceiling consumes a noticeably larger share of the money that actually reaches your bank account.

Does a bigger down payment increase how much house I can afford?

Yes, but less than you might expect. A larger down payment reduces the loan amount, so less of your monthly cap is consumed by principal and interest. Each extra $10,000 down raises the affordable price by roughly $10,000 to $11,000 at typical rates — helpful, but income and debts still set the ceiling.

Should I borrow the maximum this calculator shows?

Probably not. The result is a ceiling based on what a lender might approve, not a recommendation. Buying at the maximum leaves no room for savings, repairs, or emergencies — and lenders use gross income, while you budget with take-home pay. Most financial planners suggest targeting a payment comfortably below the limit.

References

• Consumer Financial Protection Bureau — Owning a Home: official U.S. guidance on how lenders evaluate income, debts, and loan affordability.
• Investopedia — 28/36 Rule: a detailed explanation of the front-end and back-end ratios and how underwriters apply them.
• Federal Housing Finance Agency (FHFA): the U.S. regulator overseeing conforming loan standards that shape how much lenders can approve.

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