Renting with Friends: How to Fairly Split Rent for Different Room Sizes

Co-living or sharing an apartment with friends is a great way to save money and live with people you enjoy. But when the monthly rent bill arrives, disagreements can happen. In a typical multi-room apartment, one bedroom is large with a balcony, the second is smaller, and the third is tiny. Dividing the rent equally is unfair. Let's look at how to calculate contributions fairly based on room sizes.

The Formula: Shared Space Apart, Rooms by Area

Dividing the whole rent strictly by bedroom area is common but imprecise. It assumes a flat is nothing but bedrooms, when the kitchen, bathroom and hallway get used the same by everyone whether their room is 10 m² or 18. A pure area split makes the person in the big room pay more for a kitchen they do not get more of.

So it is cleaner to split the rent into two parts:

share = common part / number of tenants + private part × (room area / total room area)

Treat 25–35% of the rent as the common part and divide it per head; the rest goes by private room area.

Worked example: rent 60 000, rooms of 18, 14 and 10 m² (42 m² total), common space at 30%. The common part of 18 000 is 6 000 each. The private part of 42 000 splits by area into 18 000 / 14 000 / 10 000. Totals: 24 000, 20 000, 16 000. An even split would be 20 000 each, and a pure area split would charge the big room 25 714 — nearly 1 700 more than it should.

Adjusting for Room Amenities

Square footage is the base, but room features affect the quality of living:

• Private Bathroom: Adding 5-10% of the total rent to that room's share is standard.
• Private Balcony: Adding 3-5% to that room's share.
• No Windows: Applying a 10-15% discount to the room's share.

Doing the Math in the App

The formula above produces two numbers per person, and you can enter both without touching a calculator. Log the rent as two expenses:

1. Shared space — 18 000 from the example, split Equally among all tenants.
2. Private rooms — 42 000 in Parts mode, with room areas as the parts: 18, 14 and 10. The amounts 18 000 / 14 000 / 10 000 appear on their own.

Parts are whole numbers. If your areas are fractional, multiply them all by ten: 18.5 / 14.5 / 10 m² becomes 185 / 145 / 100. Only the ratio matters, not the numbers themselves.

The areas are stored with the expense instead of dissolving into finished amounts. When someone moves out or you swap rooms, reopen the same record and change one number; the shares rebuild themselves. A part of 0 drops that person from the split.

How to Split Utility Bills

Unlike rent, utilities (water, power, trash) depend on consumption per person, not room size. These should be split equally among all residents. For more details, see our article on splitting utilities with roommates.

Frequently Asked Questions

How do you split rent based on room sizes?

Split the rent into two parts. The first (usually 25–35%) covers shared space — kitchen, bathroom, hallway — and is divided per head, because everyone uses it equally. The second is divided in proportion to private room areas. Per person: share = common part / number of tenants + private part × (room area / total room area).

What if two people share one room?

The rent for that specific room is typically split between the two occupants. However, utility bills (water, power) should be divided equally per person, not per room.