🏘️House Affordability Calculator

Our house affordability calculator answers the most important question in home buying before you look at a single listing: how much home can you actually afford? A home affordability calculator that only tells you what lenders will approve misleads buyers into spending at their ceiling rather than their comfort level — lender maximums reflect default risk thresholds, not financial wellness. This tool shows both what lenders will approve and what the actual monthly cost breakdown looks like, so you can make an informed decision about where to buy within the approved range.

The 28/36 Rule Explained — and Its Limits

The 28/36 rule is the foundational guideline for mortgage qualification used by conventional lenders (Fannie Mae and Freddie Mac). The front-end ratio (28%) caps your housing expenses — principal, interest, property taxes, insurance, and HOA fees — at 28% of your gross monthly income. The back-end ratio (36%) caps your total monthly debt obligations — housing plus car loans, student loans, credit card minimums, and all other recurring debts — at 36% of gross income.

Both limits apply simultaneously, and the binding constraint (whichever produces the lower maximum payment) is the relevant limit. For a borrower earning $120,000 per year ($10,000/month): the front-end limit is $2,800/month for housing. If that borrower has $600/month in existing debt, the back-end limit allows $3,600 − $600 = $3,000/month for housing. The binding constraint is the front-end at $2,800. If the borrower had $1,200/month in existing debt, the back-end limit would be $3,600 − $1,200 = $2,400 — now the binding constraint, allowing less housing than the front-end would permit. Existing debt obligations dramatically reduce housing affordability.

The 28/36 rule is a lender qualification standard, not a personal finance recommendation. Many financial planners suggest keeping housing costs below 25% of gross income (or 30% of net take-home pay) to maintain adequate cash flow for retirement savings, emergency fund contributions, and discretionary spending. Buying at the lender's maximum frequently produces "house rich, cash poor" outcomes — large equity growing in the home, but insufficient liquidity for other life goals.

FHA, VA, and Conventional Loan DTI Differences

Different mortgage programs use different DTI limits, which changes the affordable home price calculation meaningfully. FHA loans allow a 31% front-end DTI and 43% back-end DTI — more generous than conventional loans. For a borrower with $600/month in existing debt earning $10,000/month, FHA allows up to $3,700/month total debt ($10,000 × 0.43), leaving $3,100 for housing versus $2,800 under conventional rules. This difference is often meaningful in high-cost markets.

VA loans (available to eligible veterans and active-duty military) use only a 41% back-end ratio with no explicit front-end limit. With no down payment requirement and no PMI, VA loans often produce the most favorable combination of purchasing power and monthly payment for eligible borrowers. USDA loans (for rural areas) use a 29/41 guideline. "Aggressive" lenders and portfolio lenders sometimes approve up to 45–50% back-end DTI for borrowers with substantial compensating factors (large down payment, strong reserves, excellent credit).

The right loan program depends on eligibility, credit profile, down payment size, and the specific property. Use this calculator with different DTI rule settings to understand how your purchasing power changes across programs — the difference between conventional 28/36 and FHA 31/43 rules can mean tens of thousands of dollars in affordable purchase price. Use our down payment calculator to analyze the cash required at closing for each scenario.

The Hidden Costs of Homeownership That Shrink Affordability

Lenders consider principal, interest, taxes, and insurance (PITI) in the DTI calculation. Many buyers discover that property tax and insurance alone add 25–35% to their effective housing cost on top of the P&I payment — a surprise that significantly reduces the home price they can actually afford at their target monthly payment.

On a $400,000 home with 1.5% property tax and 0.5% homeowners insurance, taxes and insurance alone add $667 per month — roughly equivalent to adding a $100,000 to the mortgage at current rates. These costs are not optional, and they scale with home price, so buying a more expensive home in a high-tax jurisdiction can make affordability deteriorate rapidly even as the purchase price increases modestly. This calculator includes all these costs in both calculation modes to give you the true monthly obligation, not the misleadingly simple P&I number.

HOA fees deserve special mention for condominium and planned community buyers. A $400/month HOA fee is equivalent in budget impact to approximately $60,000 added to your mortgage. Always include HOA fees in affordability calculations, and research the HOA's financial health, reserves, and pending special assessments before purchasing — an underfunded HOA may levy unexpected large assessments in the near term that were not disclosed during the purchase process.

How to Use the Monthly Budget Mode

The monthly budget mode answers a different question than the income/DTI mode: "If I've decided I want to spend $X per month on housing total, what price home does that buy me?" This is often the more practical question for buyers who have already determined their comfortable monthly payment based on their take-home income and other spending commitments.

In budget mode, the calculator deducts all monthly housing costs — taxes, insurance, HOA, maintenance, PMI — from your budget before calculating the loan, so you get the home price consistent with your true all-in budget rather than just the P&I component. The maintenance rate (defaulted at 1.5% annually) represents the commonly cited rule of thumb that homeowners should budget 1–2% of home value per year for repairs and maintenance. Omitting maintenance from the budget calculation is a common oversight that leads buyers to underestimate the true cost of ownership.