Determining your true home buying budget requires looking far beyond the maximum loan amount a mortgage lender is willing to approve. Lenders determine what you can borrow, but only you can determine what monthly payment fits comfortably within your lifestyle.
Lenders and financial advisors rely on the 28/36 Rule as the gold standard for housing affordability.
Understanding the 28/36 Rule
The 28/36 Rule sets strict ceilings on your Debt-to-Income (DTI) ratios:
- Front-End Ratio (28%): Your total monthly housing payment (PITI: Principal, Interest, Taxes, and Insurance) should not exceed 28% of your gross monthly income.
- Back-End Ratio (36%): Your total monthly debt obligations (housing payment + credit cards + car loans + student loans) should not exceed 36% of your gross monthly income.
Calculating PITI: What's Included in a Housing Payment?
Many first-time home buyers make the mistake of calculating affordability based on principal and interest alone. Your true monthly payment includes:
- Principal: Loan balance repayment
- Interest: Mortgage interest charge
- Taxes: Local property taxes (~1.2% national average)
- Insurance: Homeowners insurance + PMI (if down payment is under 20%) + HOA fees
Gross Monthly Income = $8,000
Max Housing Payment (28%) = $8,000 * 0.28 = $2,240 / month
Example: $100,000 Household Income
For a household earning $100,000 per year ($8,333/month):
- Max Monthly Housing Payment (28%): $2,333/month
- Max Total Debt Payments (36%): $3,000/month
If you have $400/month in car payments and student loans, your total non-housing debt is $400. That leaves $2,600 available ($3,000 - $400), so the front-end limit of $2,333 remains your primary ceiling.
Calculate your custom home buying budget with interest rates, property taxes, and HOA fees using our free Mortgage Affordability Calculator.
Disclaimer: This article is for educational purposes only and does not constitute financial, legal, or medical advice. Consult a qualified professional for guidance specific to your situation.