How Much House Can I Afford

How lenders set the ceiling

Lenders do not pick a multiple of your income or a rule-of-thumb price. They run your file through a DTI test using two ratios:

In both formulas the housing figure is your full PITI payment — principal, interest, property taxes, and homeowners insurance — not merely the mortgage principal and interest. The caps themselves are reference points rather than hard rules: each lender overlays its own requirements, and VA in particular weighs residual income rather than a fixed ratio, so the ~41% figure is a rounded guide and loan officers routinely approve files above it when your income covers living costs comfortably after the payment.

The smaller of the two budgets is your ceiling — and on the default example ($120,000 income, $1,200 of other debt) it is the back-end that binds: a $2,400 housing budget against a $2,800 front-end allowance. In that regime each $100 of monthly debt retired raises the ceiling by roughly $13K. Debt has to fall below $800/month before the front-end takes over — and below that line, paying debt down no longer moves the ceiling at all.

The calculator below lets you pick a preset or set custom limits; the Binding constraint row tells you in real time which side is doing the limiting.

What the math behind the ceiling looks like

The reverse solve is two pieces. Given the monthly housing budget π and an assumption for tax + insurance as a percentage of home price τ + ι, we need to find the home price H that satisfies:

π = H × (τ + ι) / 12 + (H − down) × f

where f is the standard annuity factor (the per-dollar monthly P&I for the chosen rate and term). Solving for H:

H = (π + down × f) / ((τ + ι) / 12 + f)

Both terms carry the home price through the formula. A higher rate or higher T&I shrinks the ceiling; a longer term or larger down payment grows it. The result is the principal plus the down payment is the home price the lender will preapprove.

What moves your ceiling

Four inputs and one assumption drive the number:

1. Gross income (annual). The base of both DTI ratios. Use household gross for joint mortgages; some lenders annualize bonuses and overtime differently.
2. Other monthly debt. Car loans, student loans, credit card minimums, child support, alimony. Watch for a threshold effect: below $800/month (at the default parameters) the front-end binds and debt does not touch the ceiling; above it, each additional $100 of monthly debt removes roughly $13K (going from $1,200 down to $900 lifts the ceiling from $359,198 to $397,971).
3. Down payment. A larger down payment reduces the principal that needs P&I servicing, which is the most direct way to stretch the ceiling.
4. Rate. Even a small move from 6.5% to 7.0% matters. On a 30-year loan the monthly P&I on $400,000 goes from $2,528 to $2,661 (+$133) — money taken straight out of the budget available for principal and interest, which then lowers the ceiling.
5. T&I (annual % of price). Defaults to 1.7% — 1.2% property tax and 0.5% insurance, about the US median. Replace with your actual county tax rate and insurance quote; high-tax states swing this number 2× or more.

How to use this calculator

The page opens with $120,000 annual income, $1,200 of monthly debt, $60,000 down, 6.5% over 30 years with the conventional 28/36 DTI caps:

1. Enter your Annual household income and Other monthly debt payments. Pull the debt figure from your last month's statement: car, student loan, credit card minimums, child support, and any other recurring obligations. Exclude the housing payment itself.
2. Enter the Down payment you can bring to closing — savings, gift funds, eligible assistance.
3. Enter an Expected mortgage rate (use a real lender quote) and a Loan term (15 vs 30).
4. The Property tax + insurance field, entered as an annual percentage of home price, defaults to 1.7% — about the US median. Replace with your county tax rate and your insurance quote converted to a single percentage.
5. Open DTI limits and pick a DTI preset that matches the loan program you actually expect — Conventional (28/36), FHA (31/43), VA (~41% back-end DTI) — or set the front-end and back-end percentages yourself.
6. Read results: Maximum home price you can afford plus a full Budget breakdown showing which constraint binds, the monthly income figure, and the effective DTIs the result actually hits.

Affordability FAQ

What is the 28/36 rule?

It is the traditional lender convention: no more than 28% of gross monthly income toward housing (front-end) and no more than 36% toward total monthly debt (back-end). It dates from pre-2008 manual underwriting. Most loans today allow exceptions with compensating factors (high credit, large reserves, residual income), but 28/36 remains the textbook benchmark.

How much house can I afford with $100K income?

For a single borrower with no other debt, 20% down, 6.5% on a 30-year loan at the 28/36 caps, you can afford a home around $360,000 — set by the front-end 28% cap. The same profile under FHA's 31/43 limits reaches roughly $399,000. The exact number depends on rate, T&I assumption, and taxes — enter your income in the calculator above to see yours.

How much house can I afford with $50K income?

With clean credit, no other debt, and 20% down, expect a ceiling around $180,000 at the 28/36 caps (front-end binding); under FHA's 31% front-end limit it reaches roughly $200,000. Government programs raise that further — VA's 0%-down option removes the down-payment constraint outright, and both FHA and VA accept higher DTI. The FHA loan calculator and VA loan calculator give you the monthly payments at any of those ceilings.

Does paying off debt raise the ceiling?

Yes — when back-end is the binding constraint (as on the default example), every dollar of debt retired adds a dollar to the housing budget: moving from $1,200 of debt to $900 lifts the ceiling from $359,198 to $397,971 (+$38,773). When front-end binds instead (debt below ~$800/month), paying debt down does nothing to the ceiling — going from $700 to $400 leaves it at $410,895. If your debt is already low, the case for retiring the car note before house-hunting is cash flow, not a bigger ceiling.

Should I max my DTI to buy a bigger home?

No. Leave a buffer. The 28/36 rule is what a lender will approve; what you should spend is lower. Industry guidance: keep housing costs below 25% of take-home (not gross) income after retirement contributions, with a 3-6 month emergency fund. DTI ceilings are risk thresholds, not spending recommendations.

How does the down payment change the number?

Each dollar of down payment buys less than a dollar of home price. Going from $0 to $60,000 down lifts the ceiling from $310,184 to $359,198 — $49,014, or about $0.82 per dollar added. A higher price also carries higher tax and insurance, and those draw on the same DTI budget. Run $0 and $60,000 side by side to see it.

What credit score do I need?

Most conventional loans want 620+; FHA accepts 580 with 3.5% down; VA is program-based but lender overlays commonly require 620+. A stronger score does not raise your DTI ceiling; it improves the rate you get, and a lower rate raises the home price that fits the same budget.

What is residual income?

A second affordability test used by VA loans (and a few jumbo programs): total monthly income minus all debt service must exceed a threshold that varies by family size and region. High earners can technically have high DTIs and still qualify on residual income alone. This calculator models DTI, not residual income — VA borrowers should ask their lender for the residual income figure.

Sources: DTI benchmarks reflect the conventional 28/36 rule (Fannie Mae / Freddie Mac selling guides), FHA's 31/43 caps per HUD Handbook 4000.1, and VA's 41 back-end guideline per VA Circular 26-22-2. Property tax and insurance assumptions default to 1.7%/year — about the US median; actual figures vary substantially by state, so substitute your county's rates. The lender's preapproval letter — based on full credit, employment, residual income, and the actual program's DTI rules — is the authoritative number.

Disclaimer: This calculator provides informational estimates only and is not lending advice. A preapproval from a licensed mortgage professional is the figure that matters when you make an offer.