What is the 28/36 rule for home buying?

The 28/36 rule states that your monthly housing expense (mortgage principal, interest, taxes, and insurance) should not exceed 28% of your gross monthly income (Front-End DTI), and your total monthly debt payments (housing plus car loans, student debt, and credit cards) should not exceed 36% (Back-End DTI).

How do monthly debts (car loans, student loans) affect how much house I can buy?

Every $100 in existing monthly debt obligations directly reduces your maximum allowable monthly mortgage payment by $100, which can lower your home purchasing budget by $15,000 to $18,000 at current mortgage interest rates.

How much down payment do I need to buy a house?

While a 20% down payment eliminates Private Mortgage Insurance (PMI), conventional conforming mortgages allow down payments as low as 3%, FHA loans require 3.5%, and VA or USDA loans offer 0% down options for qualified borrowers.

What additional costs should first-time home buyers budget for?

Beyond your monthly mortgage payment (PITI), budget 2% to 5% of the purchase price for upfront closing costs, 1% to 2% annually for home maintenance and repairs, plus moving costs and utility setup fees.

House Affordability Calculator – How Much House Can I Afford?

Income & Financial Profile

Annual Household Income (Before Tax)

$/year

Monthly Debt Obligations

$/mo

Down Payment Funds

Mortgage Interest Rate

Loan Term

Underwriting Budget Rule

Estimated Purchasing Power

Maximum Affordable Home Price

$384,100

Est. Monthly Payment (PITI + HOA): $2,800.26/mo

Affordability Budget Spectrum

Down Payment (16%)$60,000

Mortgage Principal Loan Amount$324,100

Monthly Principal & Interest$2,102.11

Monthly Property Tax & Insurance$509.10

Estimated Monthly PMI$189.06

DTI Qualification Ratios28% Front / 33% Back

Lending Estimate Notice: Monthly payments, taxes, PMI, and affordability limits are estimates based on standard underwriting conventions. Actual mortgage rates, closing fees, and approval terms vary by lender and borrower credit qualifications.

How House Affordability & Mortgage Qualification Work

Determining how much house you can afford involves calculating your maximum allowable monthly mortgage payment using lender Debt-to-Income (DTI) underwriting limits, and reverse-engineering the purchase price based on your down payment and current interest rates.

Underwriters evaluate your total monthly housing cost—known as PITI (Principal, Interest, Property Taxes, and Homeowners Insurance), plus Private Mortgage Insurance (PMI) and HOA fees—to ensure housing does not exceed established percentage caps of your gross pre-tax income.

The 28/36 Underwriting Benchmark

Max Monthly Housing (PITI) = Gross Monthly Income × 28%

Max Total Monthly Debt = Gross Monthly Income × 36%

If you earn $10,000/month gross ($120,000/year), your maximum monthly housing payment should not exceed $2,800/month, and all debt payments combined (housing + auto + student loans) must not exceed $3,600/month.

The 4 Pillars of House Affordability

Gross Income: The total verifiable income earned by all co-borrowers on the loan.
Monthly Debt Obligations: Minimum monthly payments for credit cards, student loans, auto financing, and personal loans. Lower debts directly increase your purchasing budget.
Down Payment Capital: Putting 20% down avoids Private Mortgage Insurance (PMI) and lowers your monthly payment. Putting 3% to 5% down allows earlier entry into homeownership with slightly higher monthly carrying costs.
Interest Rates & Property Taxes: Higher mortgage rates increase the monthly interest portion of your payment, reducing the maximum principal amount you qualify to borrow.

Frequently Asked Questions

A common mortgage rule of thumb suggests buying a home priced between 3 to 4.5 times your gross annual income, depending on your existing debts, down payment size, and prevailing mortgage interest rates. Our calculator computes your exact qualification ceiling using lender DTI rules.

Related Real Estate & Mortgage Calculators

Explore tools to evaluate your home buying budget across Holy Calculator:

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Mortgage CalculatorCalculate full PITI payments, amortization, and loan interest

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Debt-to-Income RatioCheck your front-end and back-end underwriting approval odds

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Down Payment CalculatorDetermine upfront savings targets and equity requirements

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