What is the 28/36 rule for mortgages?

The 28/36 rule states that a household should spend no more than 28% of its gross monthly income on housing expenses and no more than 36% on total debt payments.

How do you calculate the front-end ratio?

Divide your total monthly housing costs (Principal, Interest, Taxes, Insurance) by your gross monthly income and multiply by 100.

Can I get a mortgage if my DTI is over 36%?

Yes. Many lenders, especially for FHA or VA loans, allow for a total debt-to-income ratio of up to 43% or higher, though it may come with higher interest rates.

28/36 Rule Calculator - Free & Accurate Online Calculator

28/36 Rule Calculator

Front-End Ratio — 28% Rule

Income (PKR) Do you want to input individual housing expenses separately? Front-end ratio (%)

Back-End Ratio — 36% Rule

Other debts (PKR) Total debt (PKR) Back-end ratio (%)

28/36 Rule Calculator: Precision Mortgage Affordability & Debt Strategy

Primary Goal	Input Metrics	Output	Why Use This?
Solvency Benchmarking	Gross Income, PITI, Monthly Debts	Front-End & Back-End Ratios	Align your housing budget with “Gold Standard” lending criteria to ensure loan approval and long-term liquidity.

Understanding the 28/36 Rule

The 28/36 Rule is the conservative benchmark used by mortgage underwriters to determine a borrower’s maximum creditworthiness. It splits your financial profile into two distinct perspectives:

Front-End Ratio (28%): Focuses strictly on housing costs—Principal, Interest, Taxes, and Insurance (PITI). Lenders want this to stay under 28% of your gross income to ensure your “roof” doesn’t starve your other needs.
Back-End Ratio (36%): This is your Total Debt-to-Income (DTI). It includes your PITI plus all revolving and installment debts (car loans, student loans, credit card minimums). This is often the “hard ceiling” for conventional loans.

Who is this for?

First-Time Homebuyers: Determining a realistic purchase price before falling in love with a listing.
Refinance Applicants: Checking if current debt levels allow for a lower-interest loan.
Financial Planners: Auditing client portfolios for “debt-heavy” risk factors.
Lenders: Providing a quick-glance tool for pre-qualification assessments.

The Logic Vault

The 28/36 rule operates on two simultaneous linear inequalities. To be “within the rule,” both must be true.

$$R_{front} = \frac{H}{I} \times 100 \leq 28\%$$

$$R_{back} = \frac{H + D}{I} \times 100 \leq 36\%$$

Variable Breakdown

Name	Symbol	Unit	Description
Gross Monthly Income	$I$	$	Total earnings before taxes and deductions.
Housing Costs (PITI)	$H$	$	Monthly Principal, Interest, Taxes, and Insurance.
Other Monthly Debts	$D$	$	Sum of car, student, and credit card payments.
Front-End Ratio	$R_{front}$	%	Percentage of income dedicated to housing.
Back-End Ratio	$R_{back}$	%	Percentage of income dedicated to total debt.

Step-by-Step Interactive Example

Scenario: A household earns $6,000 gross per month. They are looking at a home with a $1,500 PITI payment and have $500 in existing car and student loan payments.

Calculate Front-End Ratio:$$R_{front} = \frac{\$1,500}{\$6,000} \times 100 = \mathbf{25\%}$$Status: Pass (Under 28%)
Calculate Total Debt:$$\$1,500 + \$500 = \mathbf{\$2,000}$$
Calculate Back-End Ratio:$$R_{back} = \frac{\$2,000}{\$6,000} \times 100 = \mathbf{33.3\%}$$Status: Pass (Under 36%)

Result: This buyer is in a strong financial position for a conventional mortgage.

Information Gain: The “Ghost” Debt Variable

Most calculators ignore HOA (Homeowners Association) fees and PMI (Private Mortgage Insurance).

Expert Edge: Lenders include HOA fees and PMI inside the “28%” housing bucket, not the “36%” debt bucket. Many buyers calculate their 28% based only on the mortgage payment and find themselves disqualified later when the $400/month HOA fee is added. If your target home has an HOA, your “maximum” mortgage payment must be lowered by that exact amount to stay within the 28% limit.

Strategic Insight by Shahzad Raja

“In 14 years of fintech strategy, I’ve seen the 28/36 rule save people from foreclosure—and keep them from homeownership. Shahzad’s Tip: While 36% is the ‘safe’ back-end ratio, many FHA loans allow up to 43% or even 50% in high-cost areas. However, just because you can borrow that much doesn’t mean you should. If you are pushing past 36%, you are essentially betting that your income will grow faster than inflation. Always keep a 6-month ‘PITI Reserve’ if you plan to exceed the 36% benchmark.”

Frequently Asked Questions

Does the 28/36 rule use net or gross income?

The rule is strictly based on Gross Income (pre-tax). Underwriters use this because it is a fixed, verifiable number on your W-2 or tax returns.

What if I have high credit card debt but a low mortgage?

Your Back-End Ratio (36%) will likely be the limiting factor. Even if your housing costs are only 15% of your income, if your credit card minimums push your total debt to 40%, you may still face rejection or higher interest rates.

Is the 28/36 rule mandatory for all loans?

No. It is a guideline for Conventional Loans. FHA and VA loans often have more flexible thresholds, sometimes allowing back-end ratios up to 43% or 50% depending on credit scores and cash reserves.

Related Tools

Mortgage PITI Calculator: Breakdown your monthly payment into Principal, Interest, Taxes, and Insurance.
Debt-to-Income (DTI) Calculator: A deep dive into your back-end ratio across all loan types.
Home Affordability Calculator: Reverse-engineer your salary to find your maximum home purchase price.