How much rent can you actually afford? The 30% rule
Before comparing listings, most apartment hunts start from one number: no more than 30% of gross income on rent. It's a rough guideline, not a law, and landlords, lenders and budgeting apps all lean on it as a quick screen — but it's worth actually running the arithmetic on your own income before treating it as a hard ceiling.
The formula
Max rent = annual gross income ÷ 12 × 0.30 — 30% of gross (before-tax) monthly income.
A real example
Take a $60,000 gross annual salary.
- Monthly gross income:
60,000 ÷ 12 = $5,000. - Max rent:
5,000 × 0.30 = $1,500a month.
What a raise actually buys you
Move that same salary up to $75,000 — a $15,000, 25% raise.
- Monthly gross income:
75,000 ÷ 12 = $6,250. - Max rent:
6,250 × 0.30 = $1,875a month.
The rent ceiling rose by 1,875 − 1,500 = $375, which is exactly 25% more — the same percentage as the raise itself. Because the formula is a flat percentage of income, the ceiling always moves in lockstep with income; no raise is disproportionately more valuable to your rent budget than any other, at least by this rule.
Why gross, not net
Landlords default to gross income because it's the figure that's easy to verify on a pay stub or offer letter, and it doesn't shift with withholding elections. It also means your real, spendable room is tighter than 30% implies — taxes come out of that same income before rent or anything else gets paid.
Where the 30% figure comes from
It traces back to U.S. federal housing policy, which has long used 30% of income as the threshold for calling a household "cost-burdened" by housing. It was never a promise that 30% feels comfortable everywhere — a high-cost city and a low-cost one can both produce a "passing" 30% figure while leaving very different amounts for everything else.
It doesn't know about your other debts
This rule looks at income alone. Someone with a $600 car payment and no other debt has very different room left over than someone debt-free at the same income, even though both get the same rent ceiling here. It's worth checking your debt-to-income ratio alongside this figure before treating 30% as the final word — a landlord's own application screening often looks at both.
When the number doesn't fit your market
In many expensive metro areas, market rent for a typical one-bedroom sits well above what 30% of a typical local salary allows — that's not a math error, it's what "cost-burdened" actually looks like in practice. If your real rent runs higher than this ceiling, the number is a useful diagnostic even when it isn't achievable: it tells you exactly how much of your budget housing is eating relative to the guideline, which is the first step in deciding what else has to shrink to make room.
Run your own numbers
The free Rent Affordability calculator runs this instantly for your real income — entirely on your device.