How to Use This Calculator
Enter four numbers: your gross monthly household income (before taxes), your total existing monthly debt payments, the cash you have available for a down payment, and the current interest rate for a 30-year fixed mortgage. The calculator applies the standard 28/36 debt-to-income rule to determine the highest home price that keeps your housing costs within lending guidelines.
The loan term defaults to 30 years, which is the standard for most purchases. If you are considering a 15-year loan, select it from the dropdown — the lower term raises the monthly payment significantly, which reduces your maximum price but saves substantially on total interest paid. The optional section lets you enter your local property tax rate and insurance estimate for a more precise total monthly cost figure.
This calculator is a planning tool, not a loan approval. Lenders also evaluate your credit score, employment history, assets, and the property itself before making a decision. The number here tells you where to set your search ceiling before you start working with a lender.
How Home Affordability Is Calculated
The calculation works backward from the maximum monthly housing payment your income can support. There are two simultaneous limits — front-end DTI and back-end DTI — and the lower of the two is binding.
Step 1 — Front-end limit (28% rule): Multiply your gross monthly income by 0.28. This is the most your total housing payment (principal + interest + property tax + insurance) should be.
Step 2 — Back-end limit (36% rule): Multiply your gross monthly income by 0.36, then subtract all of your existing monthly debt payments. The result is the maximum amount left over for housing.
Step 3 — Take the lower number. Your effective maximum monthly housing payment is whichever constraint is smaller.
Step 4 — Solve for loan amount: From the max housing payment, subtract estimated property tax and insurance. The remainder is the maximum principal and interest (P&I) payment. Using the standard mortgage formula, solve backward for the loan principal that produces this payment:
Where M is your maximum P&I payment, r is the monthly interest rate (annual rate ÷ 12 ÷ 100), and n is the total number of payments (years × 12).
Step 5 — Add the down payment. Max home price = max loan amount + down payment.
The 28/36 Rule Explained
The 28/36 rule is not a guideline invented by one lender — it is the standard underwriting framework used across conventional mortgage lending, codified in Fannie Mae and Freddie Mac guidelines that govern most U.S. mortgages. Understanding each ratio separately is important because they constrain your affordability in different ways depending on how much existing debt you carry.
Front-End DTI: The 28% Housing Ratio
The front-end ratio compares your total monthly housing cost to your gross monthly income. Housing cost for this calculation is always PITI: Principal, Interest, Taxes, and Insurance. On a $350,000 home with 10% down at 6.85%, the PITI looks roughly like this:
| Component | Monthly Amount |
|---|---|
| Principal & Interest | $2,082 |
| Property Tax (1.1% / 12) | $321 |
| Home Insurance | $100 |
| Total PITI | $2,503 |
To afford this payment under the 28% rule, you would need a gross monthly income of at least $2,503 ÷ 0.28 = $8,939, or roughly $107,000 per year.
Back-End DTI: The 36% Total Debt Ratio
The back-end ratio adds all other monthly debt obligations to your housing payment and compares the total to gross income. If our hypothetical buyer also has a $450/month car payment and $300/month in student loan payments, total debt service becomes $2,503 + $450 + $300 = $3,253. The back-end DTI on $8,939/month income is $3,253 ÷ $8,939 = 36.4% — just over the 36% threshold. This is why existing debt has such a powerful effect: it directly reduces the room available for a mortgage payment.
When Lenders Allow Higher DTIs
The 28/36 rule is the conventional guideline. FHA loans allow up to 31% front-end and 43% back-end DTI with standard approvals, and some FHA loans can go to 50% back-end with compensating factors (strong credit score, large reserves). VA loans have no official DTI cap, though most VA lenders set their own limits around 41%–45%. Jumbo loans (above conforming loan limits) often require lower DTIs, typically 38%–43% back end. Regardless of the program, a lower DTI always strengthens your application and typically results in better pricing.
Down Payment Impact on Affordability
The down payment is the single most directly controllable affordability lever for most buyers. A larger down payment does three things simultaneously: it reduces the loan amount (lowering monthly P&I), it may eliminate PMI (lowering total monthly payment further), and it signals financial strength to lenders (which may improve the rate offered).
PMI: The Cost of Less Than 20% Down
Private mortgage insurance is required on conventional loans with less than 20% down. PMI rates typically range from 0.5%–1.5% of the original loan amount per year, depending on LTV ratio and credit score. On a $315,000 loan (90% LTV on a $350,000 home) with good credit, PMI might cost 0.6%/year = $1,890/year = $157.50/month. That $157.50/month PMI premium consumes part of your housing budget, reducing the max loan amount you can carry within DTI limits.
PMI is cancelled automatically when the loan balance reaches 78% of the original home value under the Homeowners Protection Act. You can also request cancellation when the balance reaches 80%. On a standard 30-year amortization schedule, this takes approximately 7–9 years without extra payments.
Down Payment Programs
FHA loans require a minimum 3.5% down payment for borrowers with credit scores of 580 or above (10% down for 580–619). Conventional loans through Fannie Mae and Freddie Mac allow 3% down for qualified first-time buyers. Many state housing finance agencies offer down payment assistance programs (DAPs) that provide grants or low-interest second loans — some forgiven after a specified occupancy period. The FHA 203(k) program allows financing both purchase and renovation costs in a single loan, which can be useful for buyers considering fixer-upper properties.
What Lenders Actually Evaluate
Home affordability calculators model the DTI calculation, but lenders evaluate several additional factors that determine whether you actually receive a loan at the rate you assumed.
Credit Score
Conventional mortgage rates are tiered by credit score in 20-point bands. The pricing difference between a 740 score and a 680 score on a $300,000 30-year loan can be 0.75–1.0 percentage points in rate, which translates to $130–$175/month. This affects not just your payment but your maximum loan amount — a higher rate means a lower max loan for the same DTI-limited monthly payment. Borrowers with scores below 620 are typically limited to FHA loans, which carry their own insurance premiums.
Employment and Income Documentation
Lenders want a 2-year history of stable income. W-2 employees typically need two years of W-2s and recent pay stubs. Self-employed borrowers usually need two years of tax returns and may have their qualifying income calculated as an average of the two years — making recent business growth less immediately useful. Recent job changes can complicate approval even with higher current income, particularly if the field changed.
Assets and Reserves
In addition to the down payment and closing costs (typically 2%–5% of purchase price), most lenders want to see 2–3 months of mortgage payments in liquid reserves after closing. A $2,500/month mortgage means $5,000–$7,500 in post-closing savings, on top of $25,000+ in down payment and $8,000–$17,000 in closing costs. Total cash needed at closing is often 3–4× what buyers expect.
Common Affordability Mistakes
The most frequent errors in home budget planning fall into predictable patterns. Knowing them in advance prevents surprises during the buying process.
1. Confusing Pre-Qualification with Actual Affordability
Pre-qualification is based on self-reported numbers without verification. The actual qualifying amount can be lower after a lender pulls your credit, verifies income, and reviews bank statements. Never make offers based on pre-qualification alone — a pre-approval with verified documentation is the accurate figure.
2. Ignoring Total PITI in Favor of P&I Only
Online payment calculators often show only principal and interest. In reality, property taxes and insurance can add 25%–40% on top of P&I. A $1,800/month P&I payment on a $300,000 home in a high-tax state might carry $400/month in property tax and $120/month in insurance — bringing the true PITI to $2,320. The calculator above uses PITI for all DTI calculations; simpler tools do not.
3. Forgetting Closing Costs
Closing costs are not rolled into most conventional purchase loans. They typically run 2%–5% of the purchase price: on a $350,000 home, that is $7,000–$17,500 due at closing on top of the down payment. Many buyers deplete their savings on the down payment and are surprised by the additional closing cost requirement. Budget for both simultaneously when planning your home purchase.
4. Buying at the Maximum
The DTI limits represent the maximum a lender will accept, not the optimal budget for your financial situation. Buying at the top of your range leaves no buffer for job changes, interest rate increases (if using an ARM), unexpected home repairs, or changes in family circumstance. Many financial planners suggest targeting a housing cost of 20%–25% of gross income rather than the full 28% — trading some price ceiling for financial resilience.
5. Omitting HOA Fees
Homeowner association fees are counted in the front-end DTI by most lenders but are easy to overlook when estimating affordability. HOA fees in condominiums, townhomes, and planned communities can range from $100–$1,000+/month depending on the property type and amenities. A $400/month HOA fee on a condo reduces your available P&I budget by exactly that amount, meaningfully lowering the loan you can carry.
Home Affordability by State
Affordability varies dramatically by location. The same income supports very different home budgets depending on median home prices, state income tax rates, and property tax rates. Here are 10 states with their key affordability parameters (2025 data):
| State | Median Home Price | Median Household Income | Effective Property Tax |
|---|---|---|---|
| Texas | $315,000 | $67,000 | 1.60% |
| Florida | $410,000 | $63,000 | 0.83% |
| California | $790,000 | $84,000 | 0.75% |
| New York | $480,000 | $74,000 | 1.62% |
| Illinois | $285,000 | $68,000 | 2.05% |
| Ohio | $220,000 | $62,000 | 1.53% |
| Georgia | $340,000 | $65,000 | 0.91% |
| Arizona | $400,000 | $64,000 | 0.60% |
| North Carolina | $330,000 | $62,000 | 0.78% |
| Washington | $560,000 | $82,000 | 0.87% |
Use the calculator above with the property tax rate for your target state to see how local taxes affect your maximum price. Illinois and New York carry effective rates more than twice those in Arizona or North Carolina — on a $300,000 home, that difference is $3,450–$4,500/year, or $290–$375/month in additional housing cost that reduces your P&I budget accordingly.
Frequently Asked Questions
How much house can I afford on a $100,000 salary?
On a $100,000 annual salary ($8,333/month gross), the standard 28% front-end DTI rule allows up to $2,333/month for all housing costs including principal, interest, property tax, and insurance. With no other debts and a 6.85% rate on a 30-year loan, that translates to a maximum home price of roughly $340,000–$370,000 depending on local property taxes and insurance costs. With significant existing debts — say $800/month in car and student loan payments — the 36% back-end limit becomes the binding constraint, dropping the max home price to around $220,000–$240,000. Use the calculator above with your exact numbers for a precise figure.
What is the 28/36 rule for home affordability?
The 28/36 rule is the standard debt-to-income guideline most conventional lenders follow. The front-end ratio (28%) says your total monthly housing costs — PITI — should not exceed 28% of your gross monthly income. The back-end ratio (36%) says all of your monthly debt obligations combined should not exceed 36% of gross income. Lenders use whichever limit is lower. Some programs allow higher DTIs: FHA loans permit up to 43%, and VA loans have no hard DTI cap, though individual lenders set their own overlays.
How does my down payment affect how much house I can afford?
A larger down payment increases the home price you can afford in two ways. First, it directly reduces the loan amount needed for any given home price, which lowers your monthly payment and makes a more expensive home fit within DTI limits. Second, putting down 20% or more eliminates private mortgage insurance (PMI), which typically costs 0.5%–1.5% of the loan amount per year — on a $350,000 loan, PMI can add $145–$440/month.
What counts as monthly debt for DTI purposes?
Lenders count all recurring monthly debt obligations that appear on your credit report: car loans, student loans, minimum credit card payments, personal loans, and child support or alimony. They do not count utilities, cell phone bills, insurance premiums, or living expenses. The critical number is the required minimum payment, not what you actually pay — so a $300/month voluntary credit card payment with a $50 minimum only counts $50 toward DTI.
Does my credit score affect how much house I can afford?
Your credit score does not directly change DTI limits, but it significantly affects the interest rate you receive. The rate spread between excellent credit (760+) and fair credit (620–639) on a conventional 30-year mortgage can exceed 1.5 percentage points. On a $350,000 loan, that is roughly $340/month — enough to shift your maximum loan amount by $50,000 or more.
Should I use gross or net income to calculate home affordability?
Use gross income — your income before taxes and deductions. This is what lenders use. However, as a personal sanity check, also verify the PITI payment feels manageable against your actual take-home pay. If the PITI is more than 30%–35% of your net pay, consider targeting a lower price point even if you technically qualify for more.
Related Calculators
Once you know your maximum home price, these calculators help you model the next steps:
- Mortgage Calculator — Enter a specific home price and see your exact monthly payment, total interest, and full amortization schedule.
- Loan Payment Calculator — Model any personal, auto, or student loan payment to understand your existing debt picture before applying.
Methodology & Sources
This calculator implements the 28/36 debt-to-income framework used in Fannie Mae and Freddie Mac conventional mortgage underwriting guidelines. The DTI assessment thresholds (Conservative ≤28%, Good 28%–36%, Borderline 36%–43%, Too High >43%) reflect standard lender practice as documented in the Fannie Mae Selling Guide and CFPB mortgage resources. Default property tax rate (1.1%) is sourced from the Tax Foundation national average effective rate. Default home insurance estimate ($1,200/year) reflects average premium data from the National Association of Insurance Commissioners (NAIC). State median home price and income figures are sourced from the U.S. Census Bureau American Community Survey (ACS) 5-year estimates and the National Association of Realtors (NAR) quarterly data, updated annually.
This tool provides estimates for planning purposes only. Actual loan qualification depends on lender-specific guidelines, credit evaluation, property appraisal, and individual underwriting decisions. Consult a licensed mortgage professional before making purchase decisions.