Rent Affordability Calculator
Work out how much rent you can comfortably afford from your gross monthly income using the 30% rule and the 40% debt-to-income cap most landlords screen against.
Maximum affordable rent
£1,500.00
- Conservative (25% of income)
- £1,250.00
- Standard (30% of income)
- £1,500.00
- Stretch (35% of income)
- £1,750.00
- Annual rent at your threshold
- £18,000.00
- Income left after rent
- £3,500.00
- Max rent by 40% DTI (after other debts)
- £2,000.00
The 30% rule is a long-standing affordability benchmark: housing costs should stay at or below 30% of gross income, leaving room for food, transport, savings and debt repayment. Conservative renters target 25%, while 35% is a stretch that only works with low non-housing debt. If you have other monthly debt payments, also check the 40% debt-to-income cap most landlords screen against.
How to use this calculator
Enter your gross monthly income (pre-tax, all sources), the percentage of income you are willing to spend on rent, and any other monthly debt payments such as car loans, student loans or minimum credit card payments. The calculator returns your maximum affordable rent at the threshold you choose, plus a side-by-side view at the conservative 25%, standard 30% and stretch 35% benchmarks, and the upper bound a landlord would typically accept under the 40% debt-to-income cap.
How the calculation works
The 30% rule comes from the Brooke Amendment to the US Housing and Urban Development Act, which capped public housing rent at a fixed share of tenant income (25% originally in 1969, raised to 30% in 1981). HUD still classifies any household paying more than 30% of gross income on housing as "cost-burdened", and more than 50% as "severely cost-burdened". The same benchmark is used by the UK Office for National Statistics, the OECD Affordable Housing Database, and most landlords. The maths is simple: maximum rent = gross monthly income × threshold ÷ 100. Landlords additionally apply a 40% debt-to-income screen — total monthly debt (rent + other obligations) should not exceed 40% of gross monthly income.
Worked example
A renter earning 5,000 per month gross with no other debt has a maximum affordable rent of 1,500 at the standard 30% rule (5,000 × 0.30). At the conservative 25% threshold the cap is 1,250, and at the 35% stretch it is 1,750. If the same renter has 500 per month of other debt, the 40% DTI cap allows up to 1,500 of rent (5,000 × 0.40 − 500), which matches the 30% rule exactly — any tighter and the renter is debt-stretched, any looser and the landlord may decline.
Frequently asked questions
What is the 30% rule for rent?
The 30% rule says you should spend no more than 30% of your gross (pre-tax) monthly income on rent. It originates in the 1969 Brooke Amendment to the US Housing and Urban Development Act, which capped public housing rents as a fixed share of tenant income; the cap was raised to 30% in 1981. HUD still defines a household paying more than 30% on housing as "cost-burdened", and the threshold is also used by the UK ONS and the OECD.
Should I use gross or net income?
The 30% rule uses gross (pre-tax) income because that is what landlords screen on and what HUD measures against. If you want a more conservative figure tied to what actually arrives in your bank account, take 30% to 35% of your net (post-tax) income instead — this works out to roughly 25% of gross for most people, which is the conservative band shown in this calculator.
Is 30% of income on rent realistic in expensive cities?
Often no. In London, New York, San Francisco and similar high-cost cities, the typical renter spends 35% to 50% of gross income on rent. That is technically "cost-burdened" by the HUD definition and leaves less room for saving and emergencies, but is a practical reality in tight rental markets. If you are above 30%, compensate by keeping other debt low and building an emergency fund.
What is the 40% debt-to-income (DTI) rule?
Many landlords cap total monthly debt obligations — rent plus car loan, student loan, minimum credit card payments and any other debt — at 40% of gross monthly income, with some accepting up to 45% for strong applicants. If you already have substantial debt, your maximum acceptable rent under the DTI rule can be lower than the 30% rule would suggest. This calculator shows both figures so you know which one is binding for you.
Does the 30% rule include utilities?
HUD's definition of "housing cost burden" includes rent plus essential utilities (electricity, gas, water, refuse). The 30% rule as most landlords and rental sites apply it covers rent only, with utilities expected to be paid separately. If you want a strict HUD-style ratio, deduct your average monthly utility cost from the maximum rent this calculator returns.
How do landlords actually decide if I can afford the rent?
Most landlords use a 30x rule (your gross annual income should be at least 30 times the monthly rent, equivalent to a 33% threshold) or a 40x rule (40 times the monthly rent, equivalent to a 30% threshold) as their headline screen, and then layer a DTI check on top. They typically also want to see a credit score above 620 to 680, no recent evictions, and at least one to two months' rent in savings. The affordability calculator is a planning tool; the lease offer depends on the landlord's full underwriting.