Mortgage Affordability Calculator

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.

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.

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.

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.

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.

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.

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 — some jumbo lenders keep the loan in-house as a portfolio loan rather than selling it, which changes the underwriting. 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.

Subtract your estimated taxes and insurance from your target monthly payment to find your P&I budget. Then work that budget backward through the loan formula. Say you want to cap your total payment at $2,300 a month. Subtract $350 for taxes and $125 for insurance, which leaves a $1,825 P&I budget. That budget supports roughly a $281,000 loan at 6.75% over 30 years. Add a $70,000 down payment and your target price comes out to about $351,000.

Yes, second-home financing carries stricter down payment and pricing rules than a primary residence. Freddie Mac caps second-home purchase loans at a 90% loan-to-value ratio, which sets your minimum down payment at 10% of the price. That's a bigger down payment than many primary-residence loans require, including FHA's 3.5% minimum. Fannie Mae also applies a separate loan-level price adjustment to second homes, so the rate typically runs higher than an identical primary-residence loan. You also cannot count rental income from the property toward the 28/36 DTI ratios above. Fannie Mae requires the owner to keep exclusive control of a second home and bars using its rental income to qualify.