People type this into search every day: how much rent can I afford?
The usual answer is 30% of your income. Budget articles repeat it. US housing policy uses it too.
That last part is the useful one. The 30% figure is a public-policy line, not a rule about your grocery bill.
Where 30% comes from
Federal housing programs treat housing as affordable when it costs no more than 30% of family income. Households above that line are called cost burdened. Households above 50% are severely cost burdened.
The Congressional Research Service spells this out in Housing Cost Burdens in 2024. HUD’s CHAS data uses the same cutoffs: monthly housing costs, including utilities, over 30% of monthly income, and over 50% for a severe burden. HUD’s glossary also defines affordable housing as paying no more than 30% of income for gross housing costs, including utilities.
The number did not start at 30%.
The old rule of thumb was “a week’s wages for a month’s rent,” about 25%. The Brooke Amendment of 1969 capped public-housing rent at 25% of household income. Congress raised the tenant contribution to 30% in the early 1980s, through the Housing and Community Development Amendments of 1981 and the Housing and Urban-Rural Recovery Act of 1983.
So 30% is the current federal assistance standard. It is also a convenient screening shortcut.
What 30% looks like in the 2024 data
CRS used the 2024 American Community Survey. Nearly half of renter households, 49.4%, were cost burdened. That is 22.7 million households. More than a quarter of renters, 26.2%, were severely cost burdened.
Owners look better on this measure. 23.9% of owner households were cost burdened, 20.7 million households.
In every US state, more than one-third of renters were cost burdened in 2024.
Those Census numbers use pre-tax household income. For renters, housing cost is gross rent: contract rent plus utilities and fuels. If you apply 30% to take-home pay, you are already being stricter than the federal statistic.
Why a percentage can still pick the wrong listing
CRS is blunt about the limit. A fixed share of income ignores what the rest of the month costs. Child care, debt, transport, and medical bills are not the same in every household.
The report uses a simple pair of households. Spend 30% on housing and a household earning $40,000 is assumed to need $28,000 for everything else. A household earning $20,000 is assumed to need $14,000. Same percentage, half the leftover.
Researchers sometimes switch to residual income. You subtract the bills you cannot skip. What remains is what you can point at rent.
Run both numbers, then keep the lower one
The rent affordability calculator does both.
It starts with monthly take-home income, then subtracts debt payments, other essential spending, and a savings target. That leftover is the cash-flow ceiling.
It also computes 30% of the income you entered.
The published result is the lower of those two figures. The conservative monthly rent.
The formula is:
min(income − debts − essentials − savings, income × 0.3)
Here are the calculator defaults:
- take-home income: $4,200
- debt payments: $350
- other essentials: $1,200
- savings target: $600
Cash-flow ceiling: 4200 − 350 − 1200 − 600 = $2,050
30% reference: 4200 × 0.3 = $1,260
Conservative rent: $1,260
In this example the 30% line is the tighter one. The extra $790 under the cash-flow ceiling is slack. It is not a reason to bid $2,000.
Raise the debts and the tighter number flips.
Keep income at $4,200. Set debts to $1,100, essentials to $1,400, and keep saving $600.
Cash-flow ceiling: 4200 − 1100 − 1400 − 600 = $1,100
30% reference: still $1,260
Conservative rent: $1,100
The percentage still says $1,260. The month only has $1,100 left after the other commitments. I would believe the $1,100.
Use take-home pay if the bills come from take-home pay
The federal cost-burden numbers use pre-tax income. Your rent comes out of what hits the bank.
If you enter take-home pay, keep the other fields in take-home terms too. Do not mix a gross salary with after-tax bills.
Irregular income is the same trap. Use a cautious month, or an average that ignores one lucky invoice. The irregular income budget is built for that.
Rent is not the whole housing cost
HUD counts utilities in gross housing cost. The ACS renter figure does too.
A lower listing with electric heat, parking, and tenant-paid water can cost more than a higher rent that includes them. Put those extras in “other essential spending” when you compare homes.
Once you have a candidate rent, run the month in the monthly budget planner. That shows what is left after food, transport, and the rest, not only after a housing percentage.
If you share the place, the roommate rent split allocates private rooms and shared space by area. The rental move-in cost adds deposits and first-month cash, so the first week does not wipe the emergency fund.
Use the lower number as a ceiling
Open the rent affordability calculator with your take-home pay, the debts that actually leave the account, and a savings number you can repeat. Keep the lower of the two results as the most you will offer.
If a listing is cheaper, keep the gap. A future rent increase or a broken washing machine will use it.