Guide · United States
The 28/36 Rule for US Mortgages — What It Is and How to Use It
Last updated 2026-04-14 · Published 2026-01-12
Plain-English guide to the classic US housing ratio limits (28% front-end, 36% back-end), how PITI fits in, and how to test your budget with our free US mortgage calculator.
What the 28/36 rule actually measures
The 28/36 guideline is a simple way to describe two debt-to-income (DTI) ratios many conventional lenders still discuss with first-time buyers. The “28” is the front-end ratio: proposed housing expenses (principal, interest, taxes, insurance—often called PITI, plus HOA if applicable) should not exceed about 28% of stable gross monthly income. The “36” is the back-end ratio: total monthly debt payments including housing should not exceed about 36% of gross income.
Important nuance: FHA, VA, USDA, and jumbo programmes can allow higher DTIs with compensating factors such as strong reserves or high credit scores. Treat 28/36 as a conservative planning band, not a universal approval ceiling.
Breaking down PITI
Principal and interest come from your loan amount, rate, and term. Property taxes and homeowners insurance are recurring housing costs lenders include in qualifying ratios in most cases. If you omit taxes and insurance in a calculator, you may overestimate how much house you can afford.
In GetMortgageCalc’s US mode, add realistic monthly tax and insurance estimates for the ZIP or county you are targeting so the front-end ratio reflects PITI, not PI alone.
Back-end ratio and hidden debts
The back-end ratio adds auto loans, student loans, credit cards (often using minimum payments or a percent of limit), child support, and other obligations. Even if you pay cards in full, underwriters may still apply a qualifying payment based on the account limit.
If your back-end ratio is tight, the fastest levers are paying down instalment debt, choosing a less expensive home, or increasing down payment to reduce principal and interest.
Worked example (illustrative)
Assume $9,000 gross monthly income ($108,000 per year). A 28% front-end cap suggests about $2,520 per month for PITI. If taxes and insurance combine to $600, you have roughly $1,920 for principal and interest. At a 6.75% 30-year fixed rate, that payment might support a loan in a specific range depending on fees, MI, and rounding—plug the exact numbers into our US calculator rather than relying on mental maths.
For the back end, 36% of $9,000 is $3,240. If you already pay $400 for a car and $250 for student loans, housing would need to fit inside the remaining headroom alongside other debts.
Try the numbers yourself
Put your income, debts, rate, and term into our browser-only calculator for United States. No signup required.
Go to calculator →Frequently asked questions
Is the 28/36 rule law?
No. It is a guideline rooted in decades of conventional underwriting practice. Actual limits depend on the agency programme, investor overlays, and automated underwriting findings.
Can I get approved with a higher DTI?
Often yes—especially with strong credit, reserves, or offsetting income stability. Your loan officer will explain what the automated underwriting system returned for your file.
Does this replace a Loan Estimate?
No. Only a lender can issue Loan Estimates and Closing Disclosures after you apply. Use calculators to prepare questions, not to lock terms.
Educational content only—not mortgage, tax, or legal advice. Confirm any decision with a licensed professional in your jurisdiction.