Home Affordability Calculator — The 28/36 Rule
The convention made adjustable: this view exposes the two DTI caps as inputs so you can see what the rule itself is doing. Stretch 28/36 to 31/43 (roughly FHA territory) and the example household's affordable price jumps well past the conservative answer; tighten to 25/33 and it falls. The point is that "what you can afford" is a policy choice wearing a math costume — the calculator just makes the policy explicit.
Home affordability under the 28/36 rule
Affordable home price
$418,557
bound by the 28% housing cap — $2,800.00/mo for housing
Breakdown
A budgeting estimate under the conventional 28/36 debt-to-income rule — not a pre-approval or lending decision. Lenders weigh credit, reserves, and loan programs this tool doesn't see.
Same income, different rule, different house
The front-end cap is the rule's conservative core: 28% of gross income for housing dates to mid-century underwriting and survives because it leaves room for everything mortgages ignore. Government programs run looser — FHA commonly evaluates near 31/43, and the qualified-mortgage back-end limit is 43% — which is how two lenders can honestly quote very different maximums to the same household.
Run your numbers at both the conservative and program caps and treat the gap between them as your judgment zone. Approving at 43% DTI means committing nearly half of gross income to debt service before taxes, retirement, or repairs — affordable to an underwriter, but not necessarily to your budget.
Questions
- Is the 28/36 rule still used?
- Yes, as the conservative benchmark for conventional loans, though programs differ — FHA evaluates near 31/43 and the qualified-mortgage rule caps back-end DTI at 43% for many loans.
- Should I borrow up to what the looser caps allow?
- Being approvable and being comfortable are different standards. The gap between the 28/36 answer and a 43%-DTI answer is money that otherwise funds savings, repairs, and slack — spend it knowingly if at all.