How much house can I afford? The 28/36 rule, down payment and the number lenders actually use
2026-09-22
Lenders will often approve more than you should borrow. The traditional guardrail is the 28/36 rule: housing costs under 28 % of gross monthly income, all debt payments under 36 %. On a $90,000 salary that caps housing at $2,100 a month β about a $310,000 loan at 6.5 %, before taxes and insurance.
Open the calculator
Work backwards from the monthly payment
- Gross monthly income Γ 0.28 = maximum housing payment (PITI)
- Subtract estimated property tax, insurance and HOA
- What remains is the principal-and-interest budget
- Put that into the loan calculator with your rate and term to find the loan amount
Down payment
20 % avoids private mortgage insurance and lowers the rate. FHA loans allow 3.5 %, many conventional programs 3β5 %, but PMI adds $100β300 a month until you reach 20 % equity. Use the savings goal calculator to find how long the down payment will take.
Stress-test it
Rerun the mortgage calculator with the rate 1 point higher and with one income removed. If the payment only works in the best case, buy less house. Keep three to six months of payments in reserve after closing.