Before you fall in love with a home, it helps to know the price range your budget actually supports. This house affordability calculator turns your income, existing debts, down payment, and loan terms into two numbers that matter: the maximum home price you can afford and the monthly principal-and-interest payment that comes with it. It uses the same debt-to-income (DTI) logic lenders use, so the result is a realistic ceiling rather than a marketing pitch.
Adjust the fields and the result card updates instantly. Raise your income, lower your other debts, or bring more cash to closing and watch your buying power move. Stress-test the interest rate up and down by half a percent, because on a 30-year loan even a small rate change quietly shrinks the home you can qualify for.
How to Use
- Enter your Annual Gross Income — your total household pre-tax income, including salary, wages, and any steady side income lenders will accept.
- Add your Monthly Debts: car payments, student loans, and credit-card minimums. Do not include rent or utilities; lenders count only recurring debt installments.
- Enter your Down Payment — the cash you plan to bring to closing. Putting 20% or more usually removes private mortgage insurance (PMI) and improves your rate.
- Set the Interest Rate (APR) you expect. If you have not locked a rate, plug in today's national average for your credit profile, then run a second scenario at +0.5% to see your downside.
- Choose the Loan Term — 30 years is the default; 15-year loans carry lower rates but a higher monthly payment.
- Set the Max Debt-to-Income (DTI) ratio. Most conventional loans want total debt payments at or below 36% of your gross monthly income.
- Optionally enter Est. Taxes, Insurance & HOA — the monthly property tax, homeowner's insurance, and association dues that sit on top of the mortgage payment.
The engine first converts your income to a monthly figure, multiplies by the DTI limit, and subtracts your existing debts and tax/insurance reserve. What remains is the monthly payment the bank will let you spend on principal and interest. It then runs that payment through the reverse mortgage formula to size the biggest loan you qualify for, and finally adds your down payment to reveal the max home price.
The Math Behind the Result
Lenders decide affordability with debt-to-income. Your monthly gross income is multiplied by the DTI cap (commonly 36%), and your existing monthly debts are subtracted. The remainder is the monthly housing payment you can support:
Affordable P&I = (Annual Income / 12 × DTI%) − Other Debts − Taxes & Insurance
To turn that monthly payment into a loan amount, the calculator uses the present-value form of the standard mortgage annuity formula:
Max Loan = M × ((1 + r)ⁿ − 1) / (r × (1 + r)ⁿ)
Where M is the affordable monthly payment, r is the monthly interest rate (annual APR ÷ 12), and n is the total number of monthly payments (years × 12). Finally:
Max Home Price = Max Loan + Down Payment
Worked example: a household earning $120,000 a year has $10,000 in gross monthly income. At a 36% DTI cap that is $3,600 available for total debt. With $800 a month in car and student loans, the remaining budget for principal and interest is $2,800. At 7% for 30 years, that payment supports a loan of about $420,861, and adding the $60,000 down payment puts the max home price near $480,861.
If the interest rate is 0%, the present-value formula divides by zero, so the engine simply splits the affordable payment across the number of months: $2,500 over 360 months buys exactly a $900,000 loan.
What Lenders Actually Check
Two ratios drive the decision:
- Front-end (housing) ratio — PITI as a share of gross monthly income, usually kept near 28%.
- Back-end (total DTI) ratio — housing plus all other debt payments, typically capped at 36% for conventional loans and up to 43%+ for qualified mortgages.
The back-end ratio is the binding constraint for most buyers. A $2,800 mortgage payment on paper can disappear quickly once you add a $500 car loan and a $300 student-loan payment. That is why this calculator asks for other debts up front: ignoring them is the single most common reason buyers qualify on paper but cannot cover the first monthly statement.
Remember that the max home price is a ceiling, not a target. Budgeting a little below it leaves room for maintenance, moving costs, and the occasional surprise repair that home ownership reliably brings.
Examples
Example 1 — The benchmark buyer. A couple earning $120,000, with $800 in monthly debts, $60,000 saved for a down payment, locking 7% for 30 years at a 36% DTI limit. Their affordable P&I is $2,800, the max loan is about $420,861, and the max home price is roughly $480,861.
Example 2 — Paying off a car first. The same couple pays off their $500 car loan before shopping. Other debts drop to $300, the affordable P&I rises to $3,300, and the max home price climbs to about $556,000 — a single payoff expands their options by roughly $75,000.
Example 3 — A six-figure household. A family earning $200,000 with no other debts and a $100,000 down payment at 7% for 30 years can support a $6,000 monthly payment, qualifying for a loan near $901,845 and a max home price around $1,901,845.
FAQ
How much house can I afford based on my income?
Multiply your gross monthly income by your DTI limit, subtract your existing monthly debts, and you get the monthly payment a lender will allow. At a 36% DTI, a $120,000 income supports about $3,600 of total debt per month; after $800 of other debts, roughly $2,800 is left for a mortgage, which supports a loan near $420,000 and a home price near $480,000 with a $60,000 down payment.
What debt-to-income ratio do lenders want?
Most conventional lenders prefer a back-end (total debt) ratio at or below 36% of gross monthly income, with housing costs alone near 28%. Some loan programs, especially FHA, allow up to 43% or slightly higher compensating factors, but a lower DTI means a safer budget and a better rate offer.
How much down payment do I need?
You can buy with as little as 3–5% down on many programs, but below 20% you will pay private mortgage insurance (PMI), which adds to the monthly bill and does not build equity. A 20% down payment removes PMI, qualifies you for a better rate, and instantly widens the price range lenders feel comfortable approving.
Why does my credit score change what I can afford?
Lenders price the interest rate by credit tier. A buyer with excellent credit might lock 6.5%, while a fair-credit buyer sees 7.5% on the same loan. On a $420,000, 30-year mortgage, that 1% gap changes the monthly payment by roughly $300 — which, fed back through the affordability formula, cuts the max home price by tens of thousands of dollars.
Should I spend the maximum I qualify for?
No. The max home price is a borrowing ceiling, not a recommended budget. Leave headroom for property tax increases, maintenance (typically 1–2% of the home value per year), and life changes like a new child or a job transition. Many financial planners advise buying comfortably below the qualified maximum.
Do property taxes and insurance count against affordability?
Yes. Lenders collect them through escrow and count them as part of your housing cost. This calculator lets you enter an estimated monthly tax, insurance, and HOA figure, which is subtracted from your payment budget. Leaving it at zero will overstate the home price you can comfortably carry.
Disclaimer
This house affordability calculator is provided for informational purposes only and does not constitute financial, lending, or tax advice. Estimates are based on the inputs you enter and the standard DTI and present-value annuity formulas; actual loan offers vary by lender, credit profile, location, and loan program. Property tax, insurance, and HOA figures are approximations. Always confirm your final approval and terms directly with a licensed mortgage lender before making an offer on a home.