Rent Affordability Calculator

Where the 30% rule comes from

The 30% guideline is not a law of finance, it is housing policy that escaped into everyday advice. US federal rules set a tenant's contribution at 25% of income in 1969 and lifted it to 30% in 1981, and the number stuck. Census statistics still call a household "cost burdened" above 30% and "severely cost burdened" above 50%. It survives because it is a reasonable default: it leaves room for retirement saving, transport, food and debt at a typical income. What it does not know is your city, your commute, your student loan or your credit history.

This calculator runs three versions of the question at once. The headline figure is 30% of gross monthly income, capped so that rent plus your existing debt payments stay under 40% of gross — the same combined-obligation logic a mortgage underwriter uses. The conservative figure is 25%, which is what you want if your income is variable or you are saving for a deposit. The third is the landlord's own test.

Worked example: 65,000 a year, no debts

Gross monthly income is 65,000 / 12 = 5,417. The 30% rule gives 1,625 a month. The conservative 25% version gives 1,354. The landlord's 40x test says you qualify for 65,000 / 40 = 1,625 — the identical number, because twelve fortieths is exactly 30%. That coincidence is worth remembering: when a New York listing says "40x the rent", it is quoting the 30% rule back at you as an admissions requirement.

Worked example: the same income with 700 of debt

Now add a 400 car payment, a 200 student loan and 100 in card minimums. Rent plus debt should stay under 40% of 5,417, which is 2,167. Subtract the 700 and only 1,467 is left for rent, so the recommendation drops from 1,625 to 1,467 — roughly 27% of gross. The 40x ceiling still reads 1,625 because landlords screen on income, not on what you owe elsewhere. That gap is exactly the trap: you can be approved for an apartment that your own balance sheet cannot carry.

Worked example: New York at 40x

A one-bedroom listed at 3,200 a month requires 3,200 x 40 = 128,000 in annual income. Two roommates earning 65,000 each clear it on combined income of 130,000, which is why sharing is the default strategy in that market. If you fall short alone, a guarantor is usually asked to show 80x the monthly rent — 256,000 for that same apartment — or you offer several months up front. Note also that some markets have changed who pays the broker: New York's FARE Act moved landlord-hired broker fees off tenants in 2025, which cut move-in cash by thousands but did nothing to the income test.

Roommate maths

When more than one person is on the lease, the tool shows both numbers: your own affordable share, and the whole-place rent if everyone contributes an equal amount and earns roughly what you do. If your roommate earns far less, that second figure is fiction — run the calculator on the lower income and multiply from there, because the weakest income sets the ceiling in practice. Also check whether the lease is joint and several, which is the norm: if your roommate stops paying, you owe the whole rent, not half of it.

What this cannot tell you

It cannot see local prices. In parts of the US Midwest, 25% of gross buys a comfortable two-bedroom; in coastal cities 30% may not buy a studio, and the honest answer becomes a longer commute, a roommate, or a smaller place. It cannot see your credit score either, and a thin file or a past eviction can outweigh a strong income at screening time.

Finally, budget for the cost of moving in, not just the monthly figure. First month, last month, a security deposit equal to one month, plus insurance and utility set-up typically means three to four times the monthly rent in cash on day one. Renters who plan only the recurring number are the ones who end up putting the deposit on a credit card, which pushes next year's debt payments up and shrinks the very budget this calculator just worked out.