House Affordability Calculator
Find out how much house you can afford with this free calculator. Enter your household income, down payment savings, existing monthly debts, mortgage rate, loan term and your target debt-to-income ratio (DTI) to instantly see the maximum home price you can purchase. The tool also includes a reverse mode: toggle to income mode and enter a target home price to see how much annual income you would need to afford it. It uses the CFPB's standard DTI guidelines (front-end 28%, back-end 36-43%) and accounts for all major housing costs: principal, interest, property taxes and insurance. Adjust assumptions like rent growth, home appreciation and investment returns to model different market scenarios and see how your affordability changes.
On a $100,000 household income with $500/month in debts, a $50,000 down payment, 6.5% rate, 30-year term and a 28% front-end DTI limit, you can afford a home priced up to --. Use the toggle below to reverse the calculation and find the income needed for a target price.
How much house can you afford?
The answer depends on four things: your income, your existing debts, the interest rate and how large a down payment you can make. Lenders use a front-end debt-to-income (DTI) ratio to limit your monthly housing costs to a set percentage of your gross income. The CFPB identifies 28% as the conventional front-end guideline, though lenders vary and some allow up to 36-43% including all debts.
This calculator works from the DTI percentage down to a monthly payment, then converts that payment to a loan size using the PMT inverse formula. Add your down payment and you have your maximum purchase price.
gross monthly income = annual income / 12
max monthly payment = (gross monthly income x DTI%) - other debts
r = annual rate / 1200
n = term years x 12
max loan = max payment x ((1 + r)^n - 1) / (r x (1 + r)^n)
max home price = max loan + down payment
Reverse: income needed for a target price
The toggle flips the calculation. You enter a target home price. The calculator subtracts the down payment to get the loan, computes the required P+I payment using the standard PMT formula, adds back your other debts, then divides by the DTI fraction to get the required gross monthly income.
loan = home price - down payment
required P+I = loan x r x (1 + r)^n / ((1 + r)^n - 1)
required gross monthly = (required P+I + other debts) / (DTI% / 100)
required annual income = required gross monthly x 12
Worked example
Inputs: $100,000 annual income, $500/month other debts, $50,000 down payment, 6.5% rate, 30-year term, 28% DTI.
- Gross monthly income = $100,000 / 12 = $8,333.33.
- DTI cap = $8,333.33 x 0.28 = $2,333.33.
- Less other debts: $2,333 - $500 = $1,833 max monthly mortgage payment.
- r = 6.5 / 1200 = 0.005417; n = 360 months.
- (1 + r)^n = 6.8485.
- Max loan = $1,833 x (6.8485 - 1) / (0.005417 x 6.8485) = $1,833 x 5.8485 / 0.037096 = $289,006 (approx.).
- Max home price = $289,006 + $50,000 = $339,006.
Reverse check: to afford a $400,000 home with the same assumptions, required annual income = roughly $118,000 (the calculator shows the exact figure).
House affordability: frequently asked questions
How much house can I afford on a $100,000 salary?
On a $100,000 annual income with $500/month in existing debts, a 28% front-end DTI limit, 6.5% rate, 30-year term and $50,000 down payment, the calculator produces a maximum home price of roughly $320,000-$350,000 depending on your exact inputs. Increasing the down payment, lowering the rate or reducing other debts all raise that ceiling.
What is the 28% rule for housing?
The 28% rule (front-end DTI) says your total monthly housing costs (principal, interest, property tax and homeowners insurance) should not exceed 28% of your gross monthly income. This is a conventional lending guideline documented by the CFPB. Some lenders allow up to 31-36% depending on credit score and other compensating factors.
How much income do I need to afford a $400,000 house?
Use the reverse-income toggle on this calculator to enter $400,000 and see the required annual income directly. As a rough guide: at 6.5%, 30 years, $50,000 down and the 28% front-end rule, you need roughly $90,000-$100,000 annual income. At higher rates or lower down payments, the required income rises.
What is a front-end DTI versus a back-end DTI?
Front-end DTI (the housing ratio) is your monthly housing costs divided by gross monthly income. Back-end DTI adds all other monthly debts (car, student loans, credit cards) to the housing cost before dividing by income. Lenders check both. This calculator defaults to the front-end ratio because it gives a cleaner housing-only affordability figure, but you can enter your other debts to see the back-end picture too.
Official sources
- DTI guidelines: Consumer Financial Protection Bureau, "What is a debt-to-income ratio?", verified June 2026.
- Qualified mortgage ceiling (43%): CFPB, Ability-to-Repay and Qualified Mortgage rule.
- PMT and present-value-of-annuity formulas: standard time-value-of-money mathematics, consistent with Federal Reserve loan amortisation guidance.
Reviewed by the CalculatorHub team, edited by James Graham, 12 June 2026. See our methodology. General information, not financial advice.