About RentFit

Last updated: October 27, 2026

RentFit is the free rent affordability calculator at rent-fit.com. You type a monthly income, any monthly debt payments, and optional living expenses. The page estimates a rent ceiling from those figures and shows how the rest of the month would split between debts, expenses, and what is left over. There is no account and no download. The arithmetic runs in your browser.

What the calculator does

The income field is labeled monthly gross income (before taxes). The chosen percentage is applied to whatever number you enter, and the result line describes that figure as a share of gross income. Monthly debt payments — car loans, student loans, card minimums, and similar — are subtracted from that percentage. The rent number cannot go below zero.

• Expenses. You can list groceries, utilities, insurance, and other costs one line at a time, or enter a single monthly total. Those amounts show up in the budget breakdown and in the leftover “savings” figure. They do not reduce the rent ceiling themselves.
• Roommates. If you set the split above one person, the page also divides the rent ceiling by that count.
• A simple status. After income is entered, RentFit labels the leftover share healthy, tight, or overextended, and draws the rent-to-income ratio on a meter.

Nothing you type is sent to a RentFit server. Closing the tab drops the numbers with it.

The 30%, 50%, and custom rules

Three buttons sit under “Affordability Rule.” Each one only changes the percentage applied to the income you entered. Debts are still subtracted afterward.

• 30% rule. Max rent equals 30% of the monthly income you entered, minus monthly debt payments. This matches the familiar “about a third of income” starting point many renters and landlords quote. On a $4,500 entry with no debts, the ceiling is $1,350.
• 50% rule. Max rent equals 50% of that same income, minus debts. The button is the looser of the two presets: half of $4,500 with no debts is $2,250. It is not a full 50/30/20 budget. In that framework, 50% of take-home pay is meant to cover all needs — rent plus groceries, utilities, and transportation — so a real needs budget often leaves less for rent than this button does. Use the expense lines if you want to see whether a 50% rent figure still leaves room for those costs.
• Custom. You set the percentage yourself, from 5% to 80%. The default in the custom field is 30. This is the control to use when a city, a household, or a savings goal does not fit either preset.

These are rules of thumb, not a landlord’s approval and not advice about what you should sign. A building may want gross income of about 2.5–3 times the monthly rent, and your own budget may need to be tighter once taxes, utilities, and a lease renewal are included. The guides below go into those differences; the calculator just does the arithmetic you ask it to do.

Guides on this site

Three articles sit next to the calculator. They are written for rent-fit.com and explain the ideas behind the buttons:

• How much rent can I afford? — the 30% rule, 50/30/20, debt, and what apartments actually cost.
• The 30% rule — where the one-third guideline comes from, and when it misleads.
• Rent budgeting — fitting rent into the rest of a monthly budget, including roommates and move-in costs.

Advertising

Google AdSense may show ads on the calculator and on those three guides. The AdSense script is not loaded on this page, the contact page, the privacy policy, or the terms of service. Details on cookies are in the privacy policy.

Who operates the site

RentFit is a free tool operated at rent-fit.com. It is not a lender, broker, or property manager, and it does not take rental applications. Questions, corrections, and privacy requests go to the site operator at contact@rent-fit.com — see the contact page. Limits on how to use the estimates are in the terms of service.