Rent Affordability Calculator
How it works
Both figures come from one ratio, used in opposite directions. Max affordable rent is gross monthly income multiplied by the ratio: at a 30% ratio, $5,000 of income supports $1,500 of rent. Income needed runs that the other way — a target rent divided by the ratio — so a $1,500 rent at the same 30% ratio calls for $5,000 of monthly income. Change the ratio and both sides move together, since they share the exact same relationship.
Frequently asked questions
Where does the "30% rule" come from, and is it really a rule?
It traces back to U.S. federal housing guidelines from the 1980s, which used 30% of income as a threshold for being "cost-burdened" by housing. It stuck as a rough rule of thumb, not because it fits everyone: in a low cost-of-living area 30% can be conservative, while in an expensive city many renters spend well above it just to have housing at all. Treat it as a starting point to adjust from, not a limit to force your budget into.
How do the two calculations relate to each other?
They are exact inverses of the same ratio. Max affordable rent multiplies income by the ratio (income × ratio); income needed divides a target rent by that same ratio (rent ÷ ratio). Feed one calculation's answer into the other at the same ratio and you land back where you started — they are two directions through one relationship, not two different rules.
Why gross income instead of take-home pay?
Gross (pre-tax) monthly income is what landlords and mortgage lenders typically ask for and screen against, so this tool uses the same figure to stay comparable to what you'll actually be evaluated on. Your real spending power is of course based on take-home pay, which is lower — worth keeping in mind separately when judging whether a given rent actually feels affordable to you.