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Home Affordability Calculator — How Much House Can I Afford?

How much house can you actually afford? This calculator works backwards from your income — the inverse of a mortgage calculator. Using the lender 28/36 debt-to-income (DTI) rule, it turns your gross income, existing debts, down payment, and the rate and term into a maximum affordable home price, and shows which DTI ratio is holding you back.

Your numbers

$

Your household income before taxes.

$

Car, student, and minimum credit-card payments (not rent).

$

Cash you’ll put toward the home up front.

$

Estimated monthly property tax + insurance + HOA.

%

The mortgage rate you expect, e.g. 6.5.

yr

Mortgage term in years, usually 15 or 30.

%

Housing ÷ income. Default 28%.

%

All debts ÷ income. Default 36%.

Results

Maximum home price$308,958.39
Maximum loan amount$268,958.39
Max monthly housing payment$2,100.00
Binding limitFront-end DTI (28%)

Payment breakdown

Principal & interest$1,700.00
Taxes, insurance & HOA$400.00

Your income is the limit here — paying down debts wouldn’t raise this. Educational estimate using the 28/36 DTI rule; not a pre-approval.

Most calculators start with a home price and tell you the monthly payment. This one runs the other way: it starts with your income and works backwards to the highest home price you can realistically afford. That’s exactly how a lender sizes your budget — using two debt-to-income (DTI) ratios known as the 28/36 rule.

Front-end vs. back-end DTI

Your DTI is simply how much of your gross (pre-tax) monthly income goes to debt. Lenders look at it two ways:

  • Front-end DTI (the “28”) — your total monthly housing payment (principal, interest, property taxes, homeowners insurance, and any HOA dues) should stay under about 28% of gross monthly income.
  • Back-end DTI (the “36”) — your housing payment plus every other monthly debt (car loans, student loans, credit-card minimums) should stay under about 36%.

Because your existing debts eat into the back-end limit, the more you already owe, the less is left for a mortgage. The binding constraint is whichever ratio allows the lower housing payment — and this calculator tells you which one it is. Both percentages are adjustable, since many lenders stretch them for strong borrowers.

From a housing payment to a home price

Once the binding housing payment is set, the calculator:

  1. Subtracts your monthly taxes, insurance, and HOA to leave the principal-and-interest (P&I) you can spend.
  2. Inverts the standard mortgage formula to find the largest loan that P&I supports at your rate and term.
  3. Adds your down payment to get the maximum home price.

A worked example

Take the default scenario: $90,000 income, $500/mo in existing debts, a $40,000 down payment, a 6.5% rate over 30 years, and $400/mo for taxes, insurance, and HOA.

  • Gross monthly income: $90,000 ÷ 12 = $7,500
  • Front-end cap: $7,500 × 28% = $2,100
  • Back-end cap: ($7,500 × 36%) − $500 = $2,200
  • Binding limit: the front-end cap is lower, so the max housing payment is $2,100
  • P&I available: $2,100 − $400 = $1,700
  • Max loan (inverting at 6.5% / 30 yr): about $268,958
  • Max home price: $268,958 + $40,000 down = about $308,958

Here income is the limit, not debt — so paying down the $500 wouldn’t raise the budget; earning more or a bigger down payment would. Add enough other debt and the back-end ratio takes over instead. If your debts ever consume the entire 36% limit, the calculator shows $0 rather than a misleading negative number.

A note on what this is — and isn’t

This is an educational estimate, not a pre-approval. It applies one widely-used guideline (28/36) and assumes the taxes, insurance, and HOA you enter are accurate and your income is steady. It deliberately excludes credit-score effects, PMI on low-down-payment loans, and loan-program specifics (FHA, VA, USDA, jumbo), all of which change real underwriting. Lenders also vary in the DTI limits and overlays they apply. Use the figure as a starting point, then get a pre-approval from a lender for a number you can rely on.

This is an educational tool, not financial advice. See our disclaimer.

Frequently asked questions

How much house can I afford on my salary?
Lenders size your home budget from your gross income using two debt-to-income (DTI) ratios, known as the 28/36 rule. Your total monthly housing payment should stay under about 28% of gross monthly income (the front-end ratio), and all of your debt payments combined under about 36% (the back-end ratio). This calculator applies both, takes whichever gives the smaller housing payment, subtracts your taxes and insurance, and works backwards to the largest loan — and therefore the highest home price — that payment supports.
What is the 28/36 rule?
The 28/36 rule is the classic affordability guideline. The "28" is the front-end DTI: your monthly housing payment (principal, interest, taxes, insurance, and HOA) should be no more than 28% of your gross monthly income. The "36" is the back-end DTI: your housing payment plus every other monthly debt — car loans, student loans, credit-card minimums — should be no more than 36%. Many lenders allow higher limits for strong borrowers, so this tool lets you adjust both percentages.
What is the difference between front-end and back-end DTI?
Front-end DTI looks only at your housing cost as a share of income. Back-end DTI looks at your housing cost plus all your other debt payments. Because your existing debts eat into the back-end limit, the more you already owe each month, the less is left for a mortgage. The binding constraint is whichever ratio produces the lower allowable housing payment — and this calculator tells you which one it is, so you know whether paying down debt would raise your budget.
How do my existing debts affect how much house I can afford?
Existing monthly debts reduce your back-end limit dollar for dollar. If your car payment, student loans, and credit-card minimums are large enough, they can pull the back-end ratio below the front-end ratio and become the binding constraint — or, in the extreme, consume the entire 36% limit, in which case you can’t qualify for any mortgage payment. When that happens this calculator shows a max home price of $0 rather than a misleading negative number, and the fix is to pay debts down or raise income.
Does this calculator guarantee I’ll be approved for that amount?
No. This is an educational estimate, not a pre-approval. Real underwriting also weighs your credit score, the loan program (FHA, VA, conventional), private mortgage insurance, cash reserves, employment history, and the specific lender’s overlays — none of which this tool models. It assumes the taxes, insurance, and HOA you enter are accurate and that your income is steady. Use the figure as a starting point, then get a pre-approval from a lender for a number you can rely on.

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