Why do landlords use 40× annual income?

It is a quick affordability screen equivalent to the 30% rule, and it is standard practice in several rental markets, including much of the UK and New York.

Should I use gross or net income?

Landlords assess gross. For your own budgeting, net income is the more realistic basis, which is why the third rule works from what you actually have left.

What if I have a guarantor?

Guarantors are often assessed at a higher multiple, commonly around 60× the monthly rent in annual income, because they carry the whole liability.

Rent Affordability Calculator

Landlords and letting agents apply income rules when assessing applications. This calculator shows the rent that three widely used rules imply, plus what is left after your own commitments.

Fill in the fields above and select Calculate to see your result and the full working.

Please note: Financial calculators produce estimates using the figures you enter. They exclude fees, taxes, insurance and rate changes unless a field asks for them. They are not financial advice — confirm any significant decision with a qualified adviser or your lender.

Formula used

The lower of: 30% of gross monthly income, annual income ÷ 40, and what remains after other commitments

How to use this calculator

Enter your gross annual income, combining both incomes if you are renting jointly.
Add monthly payments on loans, cards and car finance.
Add other essential monthly spending.
Use the lowest figure as your ceiling, not your target.

Example calculation

A $60,000 income with $350 of debt payments and $800 of other essentials:

Monthly gross = $5,000; 30% rule = $1,500

40× rule = 60,000 ÷ 40 = $1,500

Budget check = 2,500 − 350 − 800 = $1,350 → the comfortable ceiling is $1,350.

What does this result mean?

The 30% rule is a rough guideline that works less well in expensive cities, where a higher share is often unavoidable — but paying more than about 40% of gross income leaves very little room for saving or emergencies. Remember that rent is not the whole housing cost: utilities, renter's insurance, council tax or equivalent, and a deposit of one to two months all sit on top.

Frequently asked questions

Why do landlords use 40× annual income?: It is a quick affordability screen equivalent to the 30% rule, and it is standard practice in several rental markets, including much of the UK and New York.
Should I use gross or net income?: Landlords assess gross. For your own budgeting, net income is the more realistic basis, which is why the third rule works from what you actually have left.
What if I have a guarantor?: Guarantors are often assessed at a higher multiple, commonly around 60× the monthly rent in annual income, because they carry the whole liability.

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