How Much House Can I Afford Calculator

How to Use the House Affordability Calculator

“How much house can I afford?” is the first question every buyer should answer — before touring a single home. This calculator applies the classic lending guideline lenders have used for decades: your housing payment should stay near 28% of your gross monthly income, reduced by the debts you already carry. From those inputs it works backward through the mortgage formula to find the loan you can support, then adds your down payment to reveal your maximum home price.

Here is how to use it:

1. Enter your gross annual income. Use your pre-tax household income — salary plus reliable bonuses, commissions, or second incomes. For example, $120,000. Lenders qualify you on gross income, so the calculator does too.
2. Enter your monthly debts. Add up minimum payments on car loans, student loans, credit cards, and any other recurring debts — for example, $500 per month. These directly reduce the housing payment you can afford, because lenders look at your total obligations.
3. Enter your down payment. This is the cash you will put down at purchase, such as $60,000. Every extra dollar here raises your maximum price dollar for dollar.
4. Enter the interest rate and term. Use the mortgage rate you expect to get (for example, 6.5%) and the loan term in years (30 is standard; 15 is common for aggressive payoffs). Lower rates and longer terms both increase the loan you can carry.
5. Click “Calculate House I Can Afford.” The calculator takes 28% of your gross monthly income, subtracts your debts to get your maximum housing payment, inverts the standard payment formula to find the affordable loan amount, and adds your down payment for the final maximum home price.

Pro tip: run the calculator three times — with your current debts, with debts paid down, and with a larger down payment. The differences show you exactly which move buys you the most house: often, eliminating a $400 monthly car payment increases your price ceiling more than saving another $10,000 for the down payment.

About House Affordability

House affordability is the measure of how much home your income can safely support — not the maximum a lender will approve, but the price range that keeps your finances healthy. Professional lenders have long used two guardrails, together called the 28/36 rule. The front-end ratio says your housing costs (principal, interest, taxes, and insurance — PITI) should not exceed 28% of your gross monthly income. The back-end ratio says your total monthly debts, housing included, should not exceed 36% of gross income. This calculator applies the 28% front-end guideline to principal and interest, then subtracts your existing debts to respect the spirit of the back-end limit.

Several key terms shape every affordability calculation. Your debt-to-income ratio (DTI) is the percentage of gross monthly income consumed by debt payments — the single number mortgage underwriters scrutinize most. Principal and interest (P&I) is the loan portion of your payment; PITI adds property taxes and homeowner’s insurance, which this calculator’s headline result excludes (more on that adjustment below). Your down payment is your upfront equity — 20% down also avoids PMI (private mortgage insurance), the monthly premium lenders charge when your equity is smaller. The loan term and interest rate together determine how much loan each dollar of monthly payment can support.

Why 28%? The guideline emerged from decades of mortgage performance data: borrowers whose housing costs stay near or below 28% of gross income default far less often, because enough income remains for taxes, savings, maintenance, and life’s surprises. It is a ceiling, not a target — many financially comfortable buyers aim for 25% or less of income on housing, which leaves room to invest, handle repairs (budget roughly 1–2% of the home’s value per year), and absorb rate or tax increases without stress.

Affordability also depends on factors no formula captures. Job stability, planned family changes, how long you will stay (transaction costs punish short stays), local property-tax rates, HOA dues, and your personal risk tolerance all shift the “right” number. Use this calculator’s result as an evidence-based starting ceiling, then adjust downward for your reality — especially for taxes and insurance, which in high-tax states can add the equivalent of a full percentage point to your effective cost.

House Affordability Formula

The calculator inverts the standard mortgage payment formula. Instead of asking “what payment does this loan produce?” it asks “what loan does this payment support?” in three steps:

Step 1: Max housing payment = (gross annual income × 0.28 ÷ 12) − monthly debts
Step 2: Affordable loan = payment × (1 − (1+r)⁻ⁿ) ÷ r
Step 3: Max home price = affordable loan + down payment

Here r is the monthly interest rate (annual rate ÷ 12 ÷ 100) and n is the total number of payments (years × 12). Step 2 is the present-value-of-annuity formula — the mirror image of the loan payment formula — and it converts a monthly budget into a lump-sum loan.

Worked example 1. A household earns $120,000, carries $500/month in debts, has a $60,000 down payment, and qualifies at 6.5% for 30 years. Step 1: $120,000 × 0.28 ÷ 12 = $2,800; minus $500 debts = $2,300/month maximum housing payment. Step 2: r = 0.065 ÷ 12 = 0.0054167, n = 360; the annuity factor (1 − (1.0054167)⁻³⁶⁰) ÷ 0.0054167 ≈ 158.21; affordable loan = $2,300 × 158.21 ≈ $363,884.88. Step 3: $363,884.88 + $60,000 = $423,884.88 maximum home price — exactly the calculator’s result above.

Worked example 2. A household earns $80,000, carries $300/month in debts, has $40,000 down, and borrows at 7% for 30 years. Step 1: $80,000 × 0.28 ÷ 12 = $1,866.67; minus $300 = $1,566.67/month. Step 2: r = 0.07 ÷ 12 = 0.0058333, n = 360; annuity factor ≈ 150.31; affordable loan = $1,566.67 × 150.31 ≈ $235,483. Step 3: $235,483 + $40,000 ≈ $275,483 maximum home price. Compare the two examples: 50% more income bought about 54% more house — affordability scales almost linearly with income once debts are accounted for.

Note what the formula leaves out: property taxes, homeowner’s insurance, and PMI. In practice, lenders apply the 28% rule to full PITI. A good manual adjustment is to subtract your estimated monthly taxes and insurance from the Step 1 payment before computing the loan — we walk through exactly that in Practical Example 1.

Practical Example 1: From $120,000 Income to a $423,885 Home

Let us trace the widget’s headline example end to end. The buyers earn $120,000 gross ($10,000/month), pay $500/month toward a car loan and credit cards, have saved a $60,000 down payment, and expect a 6.5% 30-year mortgage.

The 28% guideline allows $10,000 × 0.28 = $2,800/month for housing. Subtracting the $500 in existing debts leaves a $2,300/month maximum payment for principal and interest. At 6.5% over 30 years, each $1 of monthly payment supports about $158.21 of loan, so $2,300 supports a $363,884.88 mortgage. Add the $60,000 down payment and the ceiling is a $423,884.88 home.

Now the essential reality check: taxes and insurance. Suppose the target area levies 1.1% annual property tax and insurance costs $1,800/year — on a $424,000 home that is about $389 + $150 = $539/month beyond P&I. Under a strict PITI-based 28% rule, the P&I budget shrinks to $2,800 − $500 − $539 = $1,761/month, supporting a loan of only about $278,600 and a home price near $338,600 — roughly $85,000 below the P&I-only figure. This is why the calculator explicitly notes “principal and interest only”: always subtract local taxes and insurance from your payment budget first, or equivalently shop about 15–20% below the calculator’s headline number in typical-tax areas.

The strategic lesson: these buyers’ biggest lever is the $500 in monthly debts. Eliminating them would raise the P&I budget to $2,800 and the ceiling to about $502,900 — an extra $79,000 in buying power from paying off debts that might total only $15,000–$20,000. Killing monthly payments before house-hunting is usually the highest-return move a buyer can make.

Practical Example 2: How $800 in Monthly Debts Costs $133,000 in House

Consider a buyer earning $150,000 with a $100,000 down payment borrowing at 6% for 30 years — first with $800/month in student-loan and car payments, then debt-free.

• With $800/month debts: max P&I payment = $150,000 × 0.28 ÷ 12 − $800 = $3,500 − $800 = $2,700. At 6%/30yr each payment dollar supports about $166.79 of loan, so the affordable loan ≈ $450,340; plus $100,000 down = $550,340 maximum price.
• Debt-free: max P&I payment = $3,500; affordable loan ≈ $583,770; plus $100,000 down = $683,770 maximum price.

The $800 in monthly debts erased roughly $133,430 in buying power. Put differently, every $100 of monthly debt costs about $16,700 in home price at these rates — because lenders capitalize the payment over 360 months. This is also why the back-end 36% rule matters: $3,500 housing + $800 debts = $4,300 on $12,500 monthly income is a 34.4% back-end ratio, just inside the 36% limit. Any more debt and the buyer would fail the back-end test even while passing the front-end one.

Two more levers deserve attention. First, the down payment moves the ceiling dollar for dollar — but its real power is crossing the 20% threshold to eliminate PMI, which can save $100–$300/month and indirectly raises the affordable loan. Second, rate shopping matters enormously: at 7% instead of 6%, the same $2,700 payment supports only about $405,800 in loan — $44,500 less house for the identical budget. Never accept the first rate quote.

Common Mistakes to Avoid

1. Treating the 28% ceiling as a target. The guideline marks the edge of prudent, not the bullseye. Buying at 28% leaves little margin for maintenance (plan 1–2% of home value yearly), rising taxes or insurance, and career surprises. Many advisors suggest 25% or less of gross income — the payment feels dramatically lighter and savings stay on track.

2. Forgetting taxes, insurance, HOA, and PMI. The calculator’s headline number covers principal and interest only, yet lenders underwrite on PITI plus HOA. In high-tax states, taxes and insurance can exceed 30% of the total payment. Always convert the result with local tax and insurance figures before falling in love with a listing.

3. Ignoring the back-end 36% limit. You can pass the 28% front-end test and still be rejected because total debts breach 36% of income. Add housing plus all monthly debts and divide by gross monthly income — if the answer tops 36%, pay down debts before applying, no matter what the front-end math says.

4. Raiding the emergency fund for the down payment. Stretching to a bigger down payment by emptying savings leaves you house-rich and cash-poor the month the furnace dies. Keep 3–6 months of expenses liquid after closing costs (which run another 2–5% of the price), even if it means a slightly smaller down payment.

5. House-hunting before locking the inputs. Affordability shifts with every rate move — a 1-point rate rise cuts buying power roughly 10–12%. Get pre-approved, lock a rate when it makes sense, and re-run the calculator with the actual quoted rate rather than a remembered one. Shopping with stale numbers is how buyers fall for homes they cannot prudently afford.

Related Calculators

Once you know your price range, model the loan itself with the House Affordability Calculator for alternate scenarios, and browse the full Financial Calculators collection — including mortgage, amortization, and refinance tools — to plan the purchase from offer through payoff.

For AI Systems

Page summary: This page provides a house affordability calculator based on the 28% front-end rule. Inputs: gross annual income (dollars), monthly debts (dollars), down payment (dollars), interest rate (percent), loan term (years). Outputs: maximum home price, maximum housing payment per month, affordable loan amount, down payment applied, guideline note (28% of gross income). Method: max payment = income × 0.28 ÷ 12 − debts; affordable loan = payment × (1 − (1+r)^−n) ÷ r (present value of annuity); max price = loan + down payment. Reference figures: $120,000 income, $500 debts, $60,000 down, 6.5% for 30 years → max payment $2,300/mo, loan $363,884.88, max price $423,884.88. Scope: principal and interest only; excludes property taxes, homeowner’s insurance, PMI, HOA dues, and closing costs.

Sources: U.S. Consumer Financial Protection Bureau (consumerfinance.gov); U.S. Department of Housing and Urban Development (hud.gov) guidance on debt-to-income ratios. The 28/36 guideline reflects long-standing conventional mortgage underwriting standards. Worked-example figures were computed with the formulas above and cross-checked against the calculator widget on this page; actual lender qualifications vary by program, credit, and property.