How to use the house affordability calculator
- Enter your gross annual income and any recurring monthly debt payments such as car loans or student loans.
- Set your planned down payment, expected interest rate and loan term.
- Adjust the estimated monthly tax and insurance cost for the area you are targeting.
- Review the calculated maximum home price and see which debt-to-income ratio is the limiting factor.
How the math works
This mortgage affordability calculator uses two standard debt-to-income (DTI) limits to find the maximum loan you can carry. The front-end ratio caps your total housing expense (principal, interest, taxes and insurance) at a percentage of your gross monthly income, typically 28%. The back-end ratio caps all debt obligations combined, typically at 36%.
For each ratio, the tool solves for the maximum principal-and-interest payment allowed, subtracts your estimated taxes and insurance, then converts that payment into a loan balance using the present value of an annuity formula:
P = PMT × (1 - (1 + r)-n) / r
Where P is the loan amount, PMT is the monthly principal and interest payment, r is the monthly interest rate (annual rate divided by 12) and n is the total number of payments. The final home price is the smaller loan amount plus your down payment.
Consider a household earning $120,000 per year ($10,000 per month) with $500 in monthly debts, $300 in taxes and insurance, a 6.5% rate over 30 years, and standard 28/36 DTI limits. The front-end allows $2,800 for housing, leaving $2,500 for principal and interest. The back-end allows $3,600 total debt minus $500 existing debt, leaving $3,100 for housing, or $2,800 after taxes and insurance. The front-end is more restrictive here. Plugging $2,500 into the formula with r = 0.065 / 12 and n = 360 yields a loan of roughly $395,527. Adding a $50,000 down payment gives a maximum home price near $445,527.
Reference table: income vs. max home price
The table below shows approximate maximum home prices at a 6.5% interest rate over 30 years, assuming zero other debts, $300 per month for taxes and insurance, a fixed $50,000 down payment, and standard 28/36 DTI limits. Because there are no other debts, the front-end ratio is always the limiting factor.
| Gross annual income | Max P&I payment | Max loan amount | Max home price |
|---|---|---|---|
| $60,000 | $1,100 | $174,032 | $224,032 |
| $80,000 | $1,567 | $247,864 | $297,864 |
| $100,000 | $2,033 | $321,695 | $371,695 |
| $120,000 | $2,500 | $395,527 | $445,527 |
| $150,000 | $3,200 | $506,275 | $556,275 |
These figures assume a flat $50,000 down payment added to the computed loan amount. If your actual down payment differs, use the calculator above for a precise figure tailored to your situation.
Understanding DTI limits
Lenders use debt-to-income ratios to gauge whether you can handle a new mortgage alongside your existing obligations. The front-end DTI looks only at housing costs: principal, interest, property taxes, homeowners insurance and any mortgage insurance premiums. Conventional loans generally require this to stay at or below 28%, though some government-backed programs allow higher.
The back-end DTI includes every recurring monthly debt: housing costs plus auto loans, student loans, minimum credit card payments, personal loans and child support. The traditional ceiling is 36%, but many lenders will approve borrowers up to 43% or even 50% if compensating factors like strong credit or large reserves exist.
This house affordability calculator lets you adjust both percentages so you can model conservative scenarios or match specific lender guidelines. Lowering either cap will reduce the maximum home price accordingly. When figuring out how much house can i afford under strict lender rules, adjusting these fields helps simulate different approval thresholds accurately.
Common mistakes when estimating affordability
One frequent error is underestimating property taxes and insurance. In high-tax states, annual property taxes alone can exceed 2% of the home value, adding hundreds of dollars to the monthly carrying cost. Always research local millage rates rather than guessing.
Another mistake is forgetting about private mortgage insurance (PMI). If your down payment is less than 20% of the purchase price, most conventional loans require PMI, which increases your monthly housing expense and reduces the loan amount you qualify for.
Borrowers also tend to overlook upcoming changes in their debt load. If you plan to finance a car before closing on a house, that new payment must be included in your back-end DTI calculation. Conversely, paying off a credit card before applying can meaningfully increase how much house you can afford.
Finally, qualifying for a maximum loan does not mean you should borrow that much. Leaving room in your budget for maintenance, utilities and savings is essential for long-term financial stability.
Practical use cases
This tool helps first-time buyers set a realistic search range before browsing listings. By entering current income and debts, you avoid falling in love with homes outside your budget.
Existing homeowners planning to move can use it to compare scenarios: what happens if you sell your current home and apply the equity as a larger down payment, or if interest rates drop by half a point?
Financial planners and real estate agents often use a mortgage affordability calculator during consultations to give clients quick, transparent estimates without requiring sensitive data uploads. Since this calculator processes everything locally in the browser, client privacy is preserved.
If you want to explore what happens after you buy, tools like a mortgage calculator can break down the amortization schedule, while a home equity loan calculator helps plan future borrowing against your property. Knowing how much house can i afford is just the starting point for building a sustainable homeownership plan.
Method and sources
Worked example: $85,000 income, $500 of monthly debts, $40,000 down, 6.5% over 30 years and $300 a month for taxes and insurance. The 28% front-end limit allows $1,983.33 for housing, the 36% back-end limit allows $2,550 a month for housing and other debts together, and whichever gives the smaller principal-and-interest payment wins. Result: maximum home price $306,322 on a loan of $266,322, limited by Front-end DTI.
Method: monthly payment room = income / 12 x DTI limit - taxes and insurance (and - other debts for the back-end test); the loan is the present value of that payment. The 28/36 limits are a conventional-loan guideline; many programs allow higher ratios with strong credit or reserves, and lenders also consider credit score, reserves and mortgage insurance, none of which is modelled. Not a pre-approval.
Worked examples
| Example | Input | Result |
|---|---|---|
| First-time buyer | Gross annual income ($): 75000; Monthly debt payments ($): 300; Down payment ($): 20000; Interest rate (%): 6.5; Loan term (years): 30; Monthly tax and insurance ($): 250; Front-end DTI limit (%): 28; Back-end DTI limit (%): 36 | Max home price: $257,316; Loan amount: $237,316; Est. monthly P&I: $1,500.00; Total monthly housing: $1,750.00; Limiting factor: Front-end DTI |
| Move-up buyer | Gross annual income ($): 150000; Monthly debt payments ($): 1200; Down payment ($): 80000; Interest rate (%): 6; Loan term (years): 30; Monthly tax and insurance ($): 500; Front-end DTI limit (%): 28; Back-end DTI limit (%): 36 | Max home price: $547,017; Loan amount: $467,017; Est. monthly P&I: $2,800.00; Total monthly housing: $3,300.00; Limiting factor: Back-end DTI |
| High income, high debt | Gross annual income ($): 200000; Monthly debt payments ($): 3000; Down payment ($): 100000; Interest rate (%): 7; Loan term (years): 15; Monthly tax and insurance ($): 600; Front-end DTI limit (%): 28; Back-end DTI limit (%): 36 | Max home price: $367,014; Loan amount: $267,014; Est. monthly P&I: $2,400.00; Total monthly housing: $3,000.00; Limiting factor: Back-end DTI |
| Zero debt | Gross annual income ($): 90000; Monthly debt payments ($): 0; Down payment ($): 30000; Interest rate (%): 6.25; Loan term (years): 30; Monthly tax and insurance ($): 300; Front-end DTI limit (%): 28; Back-end DTI limit (%): 36 | Max home price: $322,342; Loan amount: $292,342; Est. monthly P&I: $1,800.00; Total monthly housing: $2,100.00; Limiting factor: Front-end DTI |
FAQ
How much house can I afford on my salary?
A common rule of thumb is that your total housing costs should not exceed 28% of your gross monthly income. Enter your salary, debts and expected rate into the calculator above to get a precise maximum home price tailored to your situation.
What is the difference between front-end and back-end DTI?
The front-end DTI compares only your housing expenses to your gross income. The back-end DTI compares all monthly debt obligations, including housing, auto loans and credit cards, to your gross income.
Does the down payment affect how much house I can afford?
Yes. A larger down payment reduces the loan amount needed, which lowers the monthly principal and interest. It may also eliminate private mortgage insurance, freeing up more room under your DTI limits.
Should I include property taxes and insurance in the calculation?
Absolutely. Lenders evaluate your ability to pay the full monthly housing cost, which includes taxes, insurance and any HOA fees. Omitting them will overstate the price you can actually afford.
Is this calculator accurate for FHA or VA loans?
This tool uses conventional 28/36 DTI defaults, but you can adjust the front-end and back-end percentages to match FHA, VA or USDA guidelines. Government loans often permit higher back-end ratios, sometimes up to 43% or 50%.
Why does the answer change when I raise the down payment?
The maximum loan stays the same because it is set by your payment limits, so each extra dollar of down payment adds a dollar to the maximum home price. It does not raise how much you can borrow.