How Much House Can You Afford? Thinking in PITI, Not Price
Affordability explained the way lenders size it: the PITI payment, the income-times-DTI formula, a worked example, and the costs that sit outside the payment.
Ask what house you can afford and you will usually receive a multiple of your income - three times, four times, sometimes five. The honest answer is less folkloric and more useful: affordability is a monthly payment question, and the payment has a specific anatomy. Lenders size it as PITI - principal, interest, property taxes and insurance - often with association dues as a fifth member, and they cap that whole bundle at a share of your gross income after your other debts are paid. Work the anatomy in reverse and the maximum price falls out of the arithmetic. This guide builds that calculation piece by piece, shows a fully worked example, and catalogs the real costs that never appear in the payment - with the standing caveat that every figure is an estimate, and the lender's verified numbers govern.
CHAPTER 01Why the Listing Price Is the Wrong Starting Point
Price is the number on the sign, but it is not the number a household pays monthly, and two homes at the same price can demand very different lives from the same paycheck. A price across town may carry double the property tax rate; a condominium adds dues a detached house never sees; an older roof shows up as insurance and maintenance rather than as a mortgage line. Affordability discussions that start with price end with a payment nobody designed.
The payment-first view also explains results that price-multiples cannot. A household with heavy car and student payments supports a smaller mortgage than an identical income with none, at the same price point - because the lender sees the debts, not the neighborhood. Another household with a large down payment can carry a higher price at the same monthly cost, because less principal means less interest. The payment is where every variable reconciles.
This is not to say price does not matter - it sets the loan, the tax bill and often the insurance - but it is an output of the affordability calculation, not its input. The method this guide follows runs in the opposite direction of house hunting: start from the household's income and obligations, derive the largest sustainable monthly payment, and only then ask what price that payment buys at today's rates. The direction matters, because it keeps the search inside the budget instead of negotiating down from a fantasy.
CHAPTER 02PITI: The Four Parts of a Real Housing Payment
Principal is the slice of each payment that retires the loan itself. Interest is the lender's charge for the balance outstanding - the dominant component in early years of a long loan. Together they are the P&I a mortgage calculator computes from loan amount, rate and term, and they respond to exactly those three inputs and nothing else: more borrowed, higher rate, or longer term each raises the monthly cost of the same house.
Property tax is the local government's share, commonly quoted as an annual percentage of assessed value and paid monthly through escrow; rates vary widely by state and locality, which is why the same priced house can carry very different monthly bills across a metro area. Insurance is the homeowner policy the lender requires, paid annually and divided monthly. These two are not optional, they are not set by your lender, and they move with the house and its location rather than with your loan.
Two frequent guests complete the bundle. Private mortgage insurance applies on conventional loans when the down payment is below 20 percent of the price - commonly cited to cost roughly 0.5 to 1.5 percent of the loan per year until equity crosses the threshold. Homeowners association dues attach to condominiums and many planned communities and are set by the association, not by you. Lenders count all of it: the pre-approval calculator includes tax, insurance, HOA and a PMI estimate line precisely because the bundle, not the loan, is what must fit the budget.
CHAPTER 03The Formula Lenders Start From
The sizing arithmetic is almost embarrassingly simple, which is why it has survived decades of programs and marketing: monthly gross income, multiplied by a debt-to-income limit, minus existing monthly debt payments, equals the maximum housing payment. At 90,000 dollars of income and a 43 percent conventional-max limit, the ceiling is 3,225 dollars; subtract 500 dollars of car and card minimums and the largest PITI the rule allows is 2,725 dollars a month. Every affordability conversation is this subtraction wearing different clothes.
The inputs deserve one paragraph of honesty each. Income means gross, documented, before tax - the lender lends against the number on paper, not the number in your bank account, which is why taxes and living costs must be budgeted by you rather than by the formula. Debts mean the credit-report minimums and installments from the previous chapters, not your full balances. And the DTI limit is a choice: 36 percent for the conservative reading, 43 percent as the commonly cited conventional maximum, with some programs flexing above and others staying stricter.
What the formula produces is a payment budget - the single most useful number in house hunting, and the one most buyers never compute. Everything downstream is translation: the budget becomes a loan amount at a given rate and term, the loan plus down payment becomes a price, and the price becomes the search. The Mortgage Pre-Approval Calculator runs the whole chain in one click, including the tax, insurance and PMI details, so the budget arrives already translated.
CHAPTER 04From Monthly Budget Back to Maximum Price
The translation hinges on one number: the monthly cost of borrowing 100,000 dollars. At 6.5 percent over 30 years, each 100,000 borrowed costs about 632 dollars per month in principal and interest; at 5.5 percent about 568 dollars; at 7.5 percent about 699 dollars. A one-point rate move shifts the per-100,000 cost by roughly 60 to 70 dollars a month - enough to move a maximum price by tens of thousands, which is why the rate assumption you feed the math matters as much as any other input.
Apply it to the worked budget. The household above can carry 2,725 dollars of PITI. Reserve the known non-loan pieces first - about 366 dollars of property tax at a 1.1 percent rate and 150 dollars of insurance - leaving roughly 2,209 dollars for principal and interest. At the 6.5 percent factor, 2,209 dollars supports a loan near 349,000 dollars; add the 50,000 dollar down payment and the affordable price lands near 399,000 dollars. The calculator's breakdown table shows exactly this waterfall: income, minus debts, into P&I, tax, insurance and dues.
Rerun the same budget at the other figures and the sensitivity becomes visible. At a 36 percent limit the loan falls to roughly 277,000 dollars; at a 5.5 percent rate the same 43 percent budget supports meaningfully more house; a larger down payment raises the price ceiling because it raises the non-loan share. None of these is the right answer - they are the neighborhood of answers the household's arithmetic permits, and seeing several at once is what turns a number into a search range. It is an estimate, not an offer; the lender verifies everything.
CHAPTER 05What Sits Outside the Payment
The payment is the recurring cost, not the total cost, and the difference is where budgets break. Closing costs on a purchase commonly run a few percent of the price in lender and title fees, prepaid taxes and insurance - real cash due near the closing table, which the loan does not cover. Moving costs, immediate repairs and furnishing follow. A household that budgets to its last approved dollar for the payment has left nothing for the day the transaction completes.
Maintenance is the quiet permanent resident of the outside-the-payment category. Ownership replaces the landlord with a roof, a furnace and a water heater that age on their own schedules; the common planning habit is to treat a small percentage of the home's value as an annual maintenance expectation, knowing the spend arrives unevenly rather than monthly. Condominium dues shift some of this into the visible PITI+HOA bundle, but special assessments have a way of reappearing anyway.
The outside costs do not shrink the lender's maximum - the lender sizes the loan, not your life - which is precisely why self-imposed headroom matters. A payment the rule permits and a payment the household can absorb through a job change or a furnace are different numbers. The PITI method makes the first one visible; the second one is the reason many buyers deliberately shop below their ceiling, and the reason the honest answer to how much house you can afford is a range with a margin, not a point.
CHAPTER 06Turning One Number Into a Search Range
Treat the maximum price as the top of a range, not the answer. Compute it at the 43 percent limit and again at 36 percent; compute it at the rate you expect and again a point higher. The honest search band is the space between the conservative runs and the optimistic ones, and every house that interests you can be tested against it - the sibling Mortgage Calculator prices a specific candidate the same way, turning each viewing into arithmetic rather than vibes.
Then broaden the ledger to the true cost of the purchase. Cash to close - down payment plus closing costs - can be estimated early with a Closing Cost Estimator, so the savings target matches the transaction rather than the down payment alone. The difference between affording the payment and affording the purchase is exactly this line, and discovering it in the listing period rather than the contract period is the entire point of doing the arithmetic first.
End where every honest guide must: the PITI method produces the payment a standard rule might allow, and the lender's pre-approval produces the number a specific lender will write - close cousins, rarely identical twins. Re-run your calculator at different rates and limits as offers and quotes arrive, compare the results with the Loan Estimates you receive, and let the range - not the maximum - drive the search. The math cannot choose the house; it can only keep the choice inside the household's real capacity, which is the whole job.
🔑 Key takeaways
- Affordability is a monthly payment question: lenders size PITI - principal, interest, taxes, insurance, plus HOA - not the listing price.
- The sizing formula is income x DTI limit - monthly debts: at 90,000 dollars and 43 percent with 500 dollars of debts, the budget is 2,725 dollars of PITI.
- Rate moves matter: each 100,000 dollars borrowed costs about 632 dollars monthly at 6.5 percent, about 568 at 5.5 percent and 699 at 7.5 percent.
- The worked budget supports roughly a 349,000 dollar loan and 399,000 dollar price with 50,000 dollars down at 6.5 percent - a range, not a verdict.
- Cash to close, moving, maintenance and PMI (roughly 0.5-1.5 percent of the loan yearly below 20 percent down) sit outside the payment.
- Shop the range between 36 and 43 percent runs, and let the lender's verified letter - not the maximum - anchor the final search.
❓ Frequently asked questions
What does PITI stand for?
Principal, Interest, Taxes and Insurance - the four recurring parts of a full housing payment. Principal repays the loan, interest is the cost of borrowing, property taxes go to the local government and insurance covers the structure. HOA dues and PMI, when they apply, are counted alongside PITI because lenders budget them together.
Is the 3x income rule of thumb reliable?
It is a rough folk benchmark, not a sizing method, and it ignores the variables that actually move affordability: existing debts, rates, taxes, insurance and down payment. Two households with the same income can support very different prices. The DTI-based PITI method uses the same inputs a lender does, which is why its answers hold up better.
How much do property taxes change affordability?
Materially, because they ride inside the payment. A one-percentage-point difference in the annual tax rate on a 400,000 dollar home is about 333 dollars a month - budget space that could otherwise support a meaningfully larger loan. This is why the calculator takes a tax rate input and why comparing homes across tax jurisdictions is part of affordability, not a detail.
Does the calculator include PMI?
Partly, and honestly: the max-loan solve excludes PMI, but when the down payment is below 20 percent of the estimated price, the tool adds a rough PMI estimate line at about 1.0 percent of the loan per year - real quotes commonly run roughly 0.5 to 1.5 percent. Because lenders count PMI inside the DTI budget, the true maximum is somewhat lower when it applies.
Should I use the 36 percent or 43 percent DTI setting?
Use both, for different purposes. The 43 percent conventional-max setting shows the largest price standard math might allow; the 36 percent conservative setting shows what comfort costs in price. The difference between the two runs is often an entire neighborhood band, and seeing both turns an abstract debate about stretch into a concrete dollar choice.
How do HOA dues affect affordability?
Dues are part of the monthly housing cost and count inside the DTI budget like any other debt payment. A 300 dollar monthly due consumes 300 dollars of the PITI allowance, which at today's rates displaces a surprising amount of borrowing power. Condominium and planned-community buyers should enter realistic dues in the calculator before trusting any price estimate.
What if my income is irregular or self-employed?
Lenders typically count documented, stable income - often averaging two years of tax returns for self-employment - rather than best-case months. Use a conservative, documentable annual figure in the calculator rather than a peak year, because the verified version will be closer to that. The estimate's honesty about its own inputs is what makes it useful for irregular incomes.
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