How to split rent fairly between housemates or partners

There is no single fair way to split rent, but there are three defensible ones: split it equally, split it in proportion to income, or split it in proportion to the private space each person gets. Equal works when rooms and incomes are similar; income works for couples or friends whose pay differs a lot; room size works when one person has the big room with the ensuite. The rent split calculator does all three, and this guide shows the arithmetic and the trade-offs so the conversation is about values, not sums.

Three fair methods

Each method answers a different question about fairness. Equal asks: are we all getting the same thing? Income asks: is everyone giving up the same share of what they earn? Room size asks: is everyone paying for what they actually occupy? Housemates who are not a couple usually lean towards room size, while couples more often weigh income. The examples below use a rent of 2,400 a month.

Equal split

Divide the rent by the number of people: 2,400 shared by two is 1,200 each, and by three is 800 each. It is simple, transparent and needs no data. It becomes unfair when rooms differ a lot or when one person's share eats a much larger part of their pay. If everyone is roughly in the same position, though, equal avoids awkward conversations about salaries and floor plans.

Splitting by income

Each person pays rent in proportion to their share of the combined income. If A earns 3,000 a month and B earns 2,000, the combined 5,000 splits 60:40:

• A pays 2,400 × 3,000 ÷ 5,000 = 1,440.
• B pays 2,400 × 2,000 ÷ 5,000 = 960.

Both now spend 48% of their income on rent, so the burden is equal even though the amounts are not. Use the same income measure for everyone, ideally take-home pay, and agree how often to revisit it when pay changes. Keep an eye on the total too: if rent takes nearly half of combined income, the rent affordability calculator and the 50/30/20 calculator show how stretched that is.

Splitting by room size

Measure each bedroom and split the rent in proportion to floor area. With rooms of 16, 12 and 9 square metres (37 in total):

• the 16 m² room pays 2,400 × 16 ÷ 37 = 1,037.84;
• the 12 m² room pays 778.38;
• the 9 m² room pays 583.78.

The calculator does this with the room sizes you enter. Area is not the only thing that makes a room better; an ensuite, a balcony, natural light or a quieter side of the building all matter, and people sometimes adjust the shares by a fixed amount for those features.

A hybrid for shared space

A pure room-size split charges the person in the box room almost nothing for the kitchen and living room, which everyone uses equally. A common fix is to divide the rent into a shared part and a private part. Suppose you decide that half the rent pays for shared space: 1,200 is split equally (400 each), and the other 1,200 is split by room size. The shares become 918.92, 789.19 and 691.89. The calculator does not have a hybrid mode, so I run it twice: once with an equal split on the shared portion and once by room size on the private portion, then add the two. There is also a more formal approach, known as rental harmony, where housemates bid on rooms until nobody would rather swap; it is worth a look if negotiations stall.

Bills, deposits and writing it down

Utilities, internet and shared supplies are usually split equally, because usage does not follow salary or room size; the expense splitter keeps track of who paid what and settles up with the fewest transfers. How to split group expenses fairly, and settle up in the fewest payments covers that side. Whatever method you choose, write the numbers down with the date and the reason, and agree what happens when someone moves out or their income changes. Check your tenancy too: on a joint tenancy, in many countries each tenant can be held responsible for the full rent if someone else stops paying, whatever you agreed privately. Deposit rules are local; in England, for example, a deposit on most private tenancies must be protected in a government-approved scheme.