Mortgage Affordability Calculator
Your maximum affordable home price is determined by two lender rules: your PITI must stay at or below 28% of gross monthly income (front-end DTI), and all monthly debts combined must stay at or below 36% of gross monthly income (back-end DTI).
The calculator above shows the principal-and-interest payment for any home price; use the 28% front-end limit to work backwards to a purchase price that fits your income. Here is the non-obvious insight: keeping your DTI under 36% does not just get you approved — lenders often tier interest rates by DTI, meaning a lower DTI can earn you a better rate, not merely a lender's yes.
How it's calculated
Lenders measure affordability with two debt-to-income ratios, according to the CFPB and Fannie Mae guidelines. The front-end DTI compares your monthly PITI payment to your gross monthly income; conventional lenders typically cap this at 28%. The back-end DTI adds all monthly debt payments (car loans, student loans, minimum credit card payments, and the new PITI) and divides by gross income; conventional lenders typically cap this at 36%, though Fannie Mae automated underwriting can approve up to 45-50% for strong borrowers. FHA loans allow higher DTIs — often up to 43% and in some cases 50% — making them more accessible for buyers with existing debt.
To find your maximum home price, start with 28% of your gross monthly income as your PITI budget, subtract estimated taxes and insurance, and the remainder is your maximum P&I. Enter that P&I into the calculator to find the corresponding loan amount, then add your down payment to get your maximum purchase price.
A worked example
Suppose you earn $7,500 gross per month and have $400 per month in existing debt payments (car loan + student loan minimum). At the 28% front-end limit, your maximum PITI is $2,100.
Subtract $350 for taxes and $125 for insurance, leaving $1,625 for P&I. At 6.75% for 30 years, a $1,625 P&I payment corresponds to roughly a $250,000 loan.
With a $70,000 down payment, your maximum purchase price is about $320,000. Check the back-end: $2,100 PITI + $400 existing debt = $2,500, which is 33% of $7,500 gross — comfortably under the 36% back-end cap.
Common mistakes to avoid
- Confusing gross income with take-home pay. DTI is always calculated on gross (pre-tax) monthly income, not the amount deposited in your bank account.
- Omitting minimum payments on all debts. Student loans, car payments, and even zero-balance credit cards with minimum payment requirements all count in your back-end DTI.
- Forgetting that PITI — not just P&I — goes into the DTI calculation. Taxes and insurance can add hundreds of dollars per month, reducing the loan size you can qualify for.
- Buying at the maximum you qualify for. Qualifying for the max does not mean it is comfortable. A lower payment leaves room for maintenance, savings, and life changes.
- Ignoring the impact of the down payment on PMI. A down payment below 20% adds PMI to your PITI, which increases your front-end DTI and reduces how much loan you can qualify for.
Frequently asked questions
How much house can I afford on my income?
A common starting point: your total PITI payment should not exceed 28% of your gross monthly income. On $6,000 per month in gross income, that is $1,680 for PITI. After subtracting taxes and insurance, the remaining P&I determines the loan amount you can afford at current rates.
What DTI do lenders use for mortgage approval?
Conventional lenders typically use 28% front-end and 36% back-end DTI as standard guidelines, per Fannie Mae. Automated underwriting can approve up to 45-50% back-end DTI for strong borrowers. FHA allows up to 43% and sometimes 50% back-end DTI, according to HUD.
Does a lower DTI get me a better mortgage rate?
Yes, in many cases. Lenders often use risk-based pricing that assigns better rates to lower-DTI borrowers. A DTI well under 36% signals stronger repayment capacity and can reduce your rate by 0.125–0.25%, saving thousands over the life of the loan.
What counts as debt in my DTI calculation?
All monthly minimum debt payments count: car loans, student loans, personal loans, minimum credit card payments, child support, and alimony. The new mortgage PITI is also included in the back-end DTI. Income-driven student loan payments use the actual monthly payment amount in the calculation.
How does an FHA loan change my affordability?
FHA loans allow higher DTI ratios — often up to 43%, and in some cases 50%, according to HUD — which can increase your maximum purchase price if you carry existing debt. See our FHA loan calculator for FHA-specific payment estimates including mortgage insurance premiums.
How many times my salary can I borrow for a mortgage?
There's no fixed multiple — it depends on your rate, debts, and down payment, since lenders qualify you on the 28/36 DTI rule, not a flat income multiple. In our worked example above, $90,000 in gross annual income ($7,500/month) supported a roughly $320,000 purchase price at 6.75%, about 3.6 times income. A lower rate or smaller down payment changes that multiple in either direction.
Does this calculator work for jumbo or USDA loans?
The math above (28% front-end, 36% back-end) is the same underlying formula lenders use for jumbo and USDA loans, but both have different limits worth knowing. Jumbo loans are anything above the FHFA conforming loan limit ($832,750 in most counties for 2026) and typically require a larger down payment and stronger credit. USDA loans use a stricter 29/41 DTI cap and a 1% upfront guarantee fee, per the USDA Single Family Housing Guaranteed Loan Program, but allow 0% down in eligible rural areas.
Sources
We prioritize primary sources for rules, formulas, rates, limits, and definitions. See our calculator methodology and editorial policy.