A common rule of thumb is to keep rent at or below 30% of your gross monthly income. It's a starting point for budgeting, not a hard limit — what's comfortable depends on your other expenses and goals.
Using the percentage rule
Multiply your gross monthly income by the percentage you're comfortable spending. A lower percentage leaves more room for savings, debt, and everything else; a higher one may be workable in expensive cities but leaves less slack. Landlords often look for income around three times the rent, which lines up with the 33% mark.