Is the 30% rent rule right? Count what is left, not the share
Local Living Costs, AI-assisted writing · · updated
Spend no more than 30% of your income on rent. It is the first number every renter hears, used by landlords, lenders and housing agencies. It did not come from a study of household budgets, and the same 30% can be comfortable for one household and impossible for another.
Where the 30% came from
In 1969 Congress capped the rent public housing tenants could be charged at 25% of their income, in what became known as the Brooke Amendment [2]. In 1981 the cap was raised to 30%, and the figure became known as the 30 percent rule of thumb [2]. The private market adopted it as a basic test of affordability, and the US housing department now counts a household spending more than 30% of its income on housing as "cost burdened" [3]. Where the original 25% came from is unclear, and one housing explainer calls the figure "ultimately an arbitrary one" [3].
Why one share cannot fit every income
A share of income says nothing about what is left to live on [1]. In the example, with essentials of 1,500 a month in each case [1]:
| Monthly income | Rent at 30% | Left after rent | Left after essentials [1] |
|---|---|---|---|
| 2,000 | 600 | 1,400 | −100 |
| 4,000 | 1,200 | 2,800 | 1,300 |
| 8,000 | 2,400 | 5,600 | 4,100 |
The household on 2,000 is short every month while paying an "affordable" rent; the one on 8,000 could pay far more than 30% and still be fine [1]. For the lower earner to cover essentials, rent would have to stay at or under 500, a quarter of income [1]. That is the idea behind "residual income" measures of affordability: start from what a household needs to live, and see what is left for housing [1].
Check yourself
Where did the 30% rule start? As a cap on public housing rents, 25% of income from 1969, raised to 30% in 1981 [2].
What does "cost burdened" mean in US housing statistics? Spending more than 30% of income on housing [3].
Why can a 30% rent be unaffordable? On a low income, 70% left may not cover essentials; in the example, 2,000 a month leaves 100 short [1].
General information, not financial advice. A notebook entry for locallivingcosts.com, written with AI and checked by hand. The history is quoted from the sources; the example is computed from stated assumptions.