How the result is calculated
There is no law that says how much rent you can afford. There are three questions people actually ask, though, and they give different answers. Housing statisticians ask whether a household is stretched: HUD in the United States, CMHC in Canada and Australia's rental-stress figures all draw the line at housing costs above 30% of gross income. A lender's question, carried over to renting, is whether rent and every other debt payment together leave room to live. A landlord's question is narrower still: does this applicant earn enough times the rent to keep paying it?
The calculator asks all three and gives you the lowest answer, because a rent that fails any one of them is a rent that will be hard to keep up or hard to get.
housing test: rent ≤ h × M − utilities
debt test: rent ≤ t × M − utilities − debt payments
landlord test: rent ≤ 12 × M ÷ k
- M
- gross monthly income
- h
- the share of income for rent plus utilities, 0.30 to begin with
- t
- the share for rent, utilities and other debt payments, 0.36 to begin with
- k
- the landlord's multiple, in months of rent per year of income
The landlord tests are written in one form so they can be compared. "Income of three times the rent" is a monthly statement, 3 × rent ≤ monthly income, which is the same as a year's income of 36 months' rent. A British letting agent's "30 times the rent" is already yearly: 30 × monthly rent ≤ yearly income. So the American test is the stricter of the two, and 40 times, which some city landlords and many guarantor checks use, is stricter again.
Worked example
| Item | Amount | How it is obtained |
|---|---|---|
| Gross monthly income, M | 6,000.00 | 72,000 ÷ 12 |
| Housing test | 1,600.00 | 30% × 6,000 = 1,800, less 200 of bills |
| Debt test | 1,560.00 | 36% × 6,000 = 2,160, less 200 of bills and 400 of debts |
| Landlord test, three times the rent | 2,000.00 | 72,000 ÷ 36 |
| Left of gross income | 3,840.00 | 6,000 − 1,560 − 200 − 400 |
| Rent you can afford | 1,560.00 | the lowest of the three: the debt test binds |
A landlord asking for three times the rent would accept this household at 2,000. The budget tests say 1,560, and the difference is the 400 car payment and the bills, which the landlord's multiple never sees.
| Item | Amount | How it is obtained |
|---|---|---|
| Gross monthly income | 3,000.00 | 36,000 ÷ 12 |
| Income the landlord asks for | 30,000.00 | 30 × 1,000: passes |
| Rent and bills as a share of income | 38.3% | (1,000 + 150) ÷ 3,000: fails the 30% test |
| Rent you can afford by the housing test | 750.00 | 30% × 3,000 − 150 |
| Verdict | fails | the referencing check passes; the budget does not |
Reading the result
The headline is the most rent a month that passes every test you have switched on, and the caption under it names the test that set it. If the debt test binds, paying down a debt raises the rent you can carry pound for pound or dollar for dollar. If the landlord test binds, only more income or a guarantor moves it. If the housing test binds, your debts are not the problem; the 30% line is.
The table lists the most rent each test allows on its own, so you can see how far apart they are. When you enter a rent you are looking at, each test is marked as passed or failed, and the section under the table restates that rent as a share of your income and as the income the landlord's multiple asks for.
The donut splits a month of gross income into the affordable rent, bills, debt payments and what is left. What is left is before tax, so it is not spending money: tax and pension contributions come out of it first.
What changes the result
The shares. The 30% line is a measure of strain, not a target. Households on low incomes can be stretched well below it, and a high earner can rent above it without hardship. Move the slider to the share you are prepared to commit and the result moves in proportion: each percentage point is 1% of your monthly income.
Debts. Every unit of a monthly debt payment reduces the rent the debt test allows by one unit. Debt payments that end soon, such as a car loan with six months left, still count until they stop.
Bills. Whether utilities are in the rent changes what the rent can be. A flat with bills included at 1,700 and one at 1,500 plus 200 of bills cost the same, and the calculator treats them the same once you set utilities to match.
The landlord's multiple. Changing from 30 times to three times the rent (36) lowers the rent the test passes by a sixth. If you are applying with a guarantor, the guarantor's income usually has to meet a higher multiple; run the calculator with their income and the guarantor test.
Who is on the tenancy. Joint tenants' incomes are normally added together for a landlord's test. Enter the total if you are applying together.
What is not included
Tax is not worked out, because none of these tests uses take-home pay. Neither is the cash you need to move in: deposits and rent in advance are capped by law in many countries, differently in each. England caps a deposit at five weeks' rent below 50,000 pounds a year and, from 1 May 2026, rent in advance at one month; Germany caps a deposit at three months' rent excluding service charges; France at one month unfurnished and two furnished. A landlord's credit, employment and reference checks are separate from any income test and are not modelled. Nor is any housing allowance or benefit that would reduce the rent you pay yourself.
Using the result
Use the headline as a ceiling for your search, then check the rents you find against it with the rent to check field. Before you apply, ask the agent which income test they use and whether they count a partner's, a guarantor's or self-employed income, and run the calculator with that test. If the landlord would accept you but the budget tests would not, treat the gap as a warning rather than a green light: the tests that see your debts and bills are the ones that describe your month.