How much house can you actually afford? Not the number Zillow flashes at you, not the number a commission-hungry agent suggests — the number a mortgage underwriter will sign off on. In the United States that number comes from a formula lenders have used for decades: the 28/36 rule. Your housing payment should stay under 28 percent of gross monthly income, and all your debts combined — housing plus car payments, student loans, credit card minimums — should stay under 36 percent. This calculator runs both tests, takes the stricter one, and converts it back into a home price, so you shop with the same math the bank uses.

Let us do it with real numbers. Take a household earning $100,000 a year in Columbus, Ohio, with $500 a month in existing debts (a student loan and a credit card minimum), $40,000 saved for a down payment, borrowing at 6.5 percent for 30 years. First, monthly gross income: $100,000 divided by 12 is $8,333. The 28 percent front-end cap gives $2,333 a month for housing — that covers principal, interest, tax, and insurance. The 36 percent back-end cap gives $3,000 total for all debts; subtract the existing $500 and you get $2,500 available for housing. The tighter limit wins, so the budget is $2,333 a month. Now the calculator runs the amortization formula in reverse: at 6.5 percent over 360 months, a $2,333 payment supports a loan of about $369,000. Add the $40,000 down payment and the maximum affordable home price is roughly $409,000.

Notice what the 28/36 rule ignores, because you should not. It ignores property tax and insurance differences — that $2,333 has to cover PITI, not just principal and interest, so in high-tax states like New Jersey or Illinois your true buying power is lower than the headline number. It ignores HOA dues, which can run $200 to $500 a month in many Sun Belt communities. It ignores the lifestyle question entirely: just because a lender will approve $409,000 does not mean you should spend it, especially if you value travel, savings, or sleeping at night. Plenty of financial planners quietly suggest the 25 percent rule — housing under 25 percent of take-home pay — as the real comfort zone.

Debt is the silent killer in this math, and the back-end ratio is where it shows. Watch what happens when our Columbus household carries $1,200 a month in debts instead of $500 — a car payment plus heavier student loans. The back-end cap becomes $3,000 minus $1,200, or $1,800, which now binds tighter than the $2,333 front-end number. The affordable loan drops to about $285,000 and the max home price to roughly $325,000. That $700 of monthly debt just erased $84,000 of buying power. This is why every honest home-buying guide in America screams the same advice: kill high-interest debt before you house-hunt, and do not — under any circumstances — finance a new car between pre-approval and closing. Lenders re-pull your credit before funding, and a fresh auto loan has torpedoed countless closings.

Down payment size moves the needle in two ways. Obviously, more cash down means a bigger price for the same loan — our $40,000 down payment added $40,000 of buying power dollar for dollar. Less obviously, crossing the 20 percent threshold kills PMI, which effectively raises your monthly budget: every $100 of PMI you avoid is $100 more of P&I the 28 percent cap can absorb, worth roughly $15,000 to $17,000 of additional loan at current rates. First-time buyers should also know about the programs designed for them: FHA loans allow 3.5 percent down, VA loans offer zero down for eligible veterans, and many states run first-time buyer assistance with down payment grants — all of which change the down payment input and therefore the answer.

Interest rates swing affordability harder than most people feel intuitively. At 6.5 percent our household affords $409,000. Drop the rate to 5.5 percent and the same $2,333 payment supports about $451,000 — a $42,000 swing from a single point. Push it to 7.5 percent and buying power falls to roughly $373,000. This rate sensitivity is why shopping lenders matters: even an eighth of a point difference, sustained over 30 years, is worth thousands. Get quotes from at least three lenders — a bank, a credit union, and a mortgage broker — and compare APRs, not just rates.

One more reality check before you trust any number on this page: pre-approval is not a promise. Lenders verify income, assets, employment, and credit at application and again before closing, and the final approval can come in lower if anything shifted. Use this calculator to set your search range, then get a real pre-approval letter to find out what the bank will actually fund. And when you tour homes, run each candidate's real tax bill and insurance quote through the mortgage calculator — the affordability number is the ceiling, but the monthly payment on a specific house is what you will actually live with.

The rent-versus-buy question sits underneath all of this, and the honest answer depends on your time horizon. Buying wins when you stay put long enough for appreciation and principal paydown to overcome transaction costs — typically 5 to 7 years, the break-even point in most US markets after accounting for 6 percent agent commissions on the eventual sale, closing costs on the purchase, and maintenance along the way. In high price-to-rent markets like San Francisco or New York, where a $800,000 condo might rent for $3,200, renting and investing the difference often wins mathematically for a decade or more. In affordable markets like Columbus or Kansas City, buying usually wins by year four or five. The New York Times rent-versus-buy calculator popularized this framework, but the core inputs are simple: how long you will stay, and the local ratio of prices to rents.

Do not forget the emergency fund, because homeowners need a bigger one than renters. Financial planners typically suggest 3 to 6 months of expenses for renters but 6 months of housing costs plus a repair reserve for owners — on our $409,000 example, that means $12,000 to $15,000 in accessible savings beyond the down payment and closing costs. A furnace replacement ($5,000 to $10,000), a roof ($10,000 to $20,000), or a sewer line ($5,000 to $15,000) can arrive without warning, and none of them accept excuses. If buying would drain you to zero, you are not ready — keep renting and saving.

Hidden costs of homeownership routinely surprise first-time buyers who budgeted only for PITI. Beyond maintenance at 1 to 2 percent of value yearly, expect higher utility bills than apartment living, lawn care or HOA landscaping fees, pest control, and the slow drip of furnishings and tools a house demands. A realistic all-in housing budget adds 30 to 40 percent on top of the PITI payment in the early years. None of this means buying is wrong — equity building and forced savings make it one of the best wealth builders available to middle-class Americans — but go in with eyes open, margin in the budget, and a clear-eyed view of what each dollar of house truly costs you every single month.

Salary-specific numbers make the rule concrete, so here is what the 28/36 math produces at 6.5 percent for 30 years with 20 percent down and modest debts. On a $75,000 salary ($6,250 a month gross), the 28 percent cap allows $1,750 a month for housing, supporting roughly a $277,000 loan — about a $346,000 home. On $150,000 ($12,500 a month), the cap is $3,500 a month, supporting roughly a $554,000 loan or a $692,000 home. On $200,000 ($16,667 a month), it is $4,667 a month, roughly a $738,000 loan or a $923,000 home. These assume minimal other debts; every $500 of monthly debt payments erases roughly $79,000 of buying power at current rates. Bookmark that ratio — it is the fastest mental math in home buying.

Loan programs bend the 28/36 rule in important ways. Conventional loans conforming to Fannie Mae and Freddie Mac guidelines generally cap at 36 percent back-end DTI, stretching to 45 percent with strong compensating factors like large reserves or excellent credit. FHA loans are far more flexible: they allow front-end ratios up to 46.99 percent and back-end up to 56.9 percent with automated underwriting approval — which is why FHA is the workhorse for first-time buyers with student loans. VA loans have no official DTI cap at all; instead they use a residual income test, requiring enough monthly income left over after all obligations to cover your family's living costs by region. USDA loans cap around 41 percent. The program you choose changes the answer this calculator gives, so run the numbers with your actual loan type's limits in mind.

If the calculator's answer disappoints you, four levers can move it. First, attack monthly debts — paying off a $400 car payment restores about $63,000 of buying power. Second, grow the down payment; beyond the dollar-for-dollar effect, crossing 20 percent eliminates PMI and effectively raises your monthly budget. Third, buy down the rate: one discount point (1 percent of the loan) typically cuts the rate by a quarter point, and on a $400,000 loan that quarter point is worth roughly $66 a month — about $10,000 of extra buying power. Fourth, consider a less expensive market or a smaller home; the price-to-income math varies enormously by metro.

Geography is the hidden variable in every affordability calculation. The same $100,000 salary that comfortably buys a $409,000 home in Columbus buys far less in practice in San Diego, where property taxes, insurance, and HOA dues consume a bigger slice of the 28 percent, and where $409,000 barely buys a condo. Conversely, in markets like Pittsburgh or Memphis, that budget buys a detached home with room to spare. When relocating, re-run the calculator with the destination's actual tax rates and insurance costs — national averages will mislead you by tens of thousands.

A note on dual incomes: lenders use combined gross income, which supercharges affordability — two $75,000 earners qualify like one $150,000 earner. But budget on one income if you can. Jobs change, parental leave happens, and a mortgage that requires both paychecks at full strength leaves no margin. The happiest homeowners are the ones whose payment would still work if one income took a hit.

Renters with strong savings but modest income have one more path: house hacking. Buying a duplex or triplex and living in one unit while renting the others lets lenders count a portion of the rental income toward your qualifying income — FHA even allows 3.5 percent down on multi-unit properties up to four units if you live in one. A $500,000 duplex with $1,800 a month in rental income can qualify a buyer who could never afford a $500,000 single-family home. It is landlording, with all its headaches, but it is also the fastest affordability hack in American real estate.

Do not overlook down payment assistance. Every US state runs housing finance agency programs offering grants or forgivable second mortgages for first-time buyers — often $10,000 to $25,000 that never needs repaying if you stay put for 5 to 10 years. These programs stack with FHA's 3.5 percent minimum, meaning some buyers close with almost nothing out of pocket. Search your state's housing finance agency site before assuming you need years to save; the calculator's down payment input might be smaller than you think.

Finally, treat the maximum as a ceiling, never a target. Lenders approve the largest loan their formulas allow; they do not check whether you still want to max out your 401(k), save for college, or take a vacation. A useful gut check: if the payment on your max approval leaves you saving less than 15 percent of income for retirement, you are buying too much house. The calculator tells you what the bank will fund — your budget tells you what you should spend. That discipline is what turns a house into a home you can actually enjoy.

With the pre-filled defaults — Annual Gross Income $100,000, Monthly Debt Payments $500, Down Payment Available $40,000, Interest Rate (APR) 6.5%, Loan Term 30 yrs — the House Affordability Calculator returns Max Housing (28% Rule) $2,333.33, Max Debts (36% Rule) $2,500.00, Max Monthly Payment $2,333.33, Max Loan Amount $369,158.58, Max Affordable Home Price $409,158.58. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.