Four friends, three bedrooms, one shared room
Two people sharing the big room give up privacy, but they also get the most space. The hybrid split prices both: they pay per head for the shared rooms and half the big room each.
Kitchen, living room, shared bath. The rest of the rent follows each room.
Closet, light, noise
Closet, light, noise
Closet, light, noise
Weights you agree on
The link holds the whole split. Nothing is stored on our server until you make it a household.
The working, room by room
| Room | People | Weight | Shared part | Room part | Pays |
|---|---|---|---|---|---|
| Big room | 2 | 230 × 1 | $765.00 | $935.00 | $1,700.00 |
| Room B | 1 | 120 × 1 | $382.50 | $487.83 | $870.33 |
| Room C | 1 | 110 × 1 | $382.50 | $447.17 | $829.67 |
| Total | 4 | $1,530.00 | $1,870.00 | $3,400.00 |
Weight = floor area × the room’s multiplier (private bath and factors). Unrounded parts are shown; the “Pays” column is rounded to cents so it adds up exactly.
The numbers, step by step
Four friends rent a $3,400 three-bedroom. Two of them share the 230 sq ft main bedroom; the other two take rooms of 120 and 110 sq ft. 45% of the rent covers the shared space and is split by four heads; the rest follows bedroom floor area.
- Big room pays $1,700.00, $850.00 each: 1.5× average floor area, 2 people share the common space.
- Room B pays $870.33: 0.78× average floor area.
- Room C pays $829.67: 0.72× average floor area.
- Total: $3,400.00, exactly the rent.
Names and amounts are samples. Change any number in the calculator above and the result updates.
A fairness test you can run together
Fair-division research calls a split envy-free when each person feels they got the best piece “in her own estimation”, as Francis Su puts it. Ask: at these prices, would anyone rather swap rooms? If not, nobody envies anyone. Bid mode makes that a guarantee.
Keep it running
Turn this into a household: rent posts at the agreed split each month, bills split by days home, and housr works out who owes whom. Roommates join with a link and a name.
Make it a householdWhen this split is fair, and when it isn’t
Fair when
- Each person in the shared room pays for half the room’s space, which is often still less than a private room, reflecting the lost privacy.
- Four people use the kitchen and bathroom, so the shared-space part is split four ways.
- You can raise the shared-space percentage if the flat’s living room is big, which shifts money toward per-person shares.
Not so fair when
- If the two sharers dislike sharing and only agreed to make the rent work, a privacy discount on their room (lower its area) is reasonable.
- If the sharers are a couple, see the couple scenario: the same maths, different expectations.
- Rotating rooms every few months is another fair answer, and it makes the split simpler.
This is general information about splitting costs between yourselves, not legal advice. Your lease and your state’s law decide what you owe the landlord.
Sources
- Spliddit, Assign Rooms and Share Rent. Checked 2026-10-05.
- Gal, Mash, Procaccia and Zick, Which Is the Fairest (Rent Division) of Them All? (J. ACM 64(6), 2017). Checked 2026-10-05.
- Francis Su, Harvey Mudd College, Fair Division Calculator (historical page). Checked 2026-10-05.
Related situations
A couple and a single: who pays what?
Per room is unfair to the single person; per person is unfair to the couple, who share one bedroom. The hybrid splits the shared space by heads and the bedrooms by size.
Open the example Split rentThree unequal bedrooms, one rent
When the biggest room is almost twice the smallest, an equal split means the small room quietly pays for the big one. Weighting by floor area fixes that in a way everyone can check.
Open the example Split rentBid for rooms so nobody wants to swap
Instead of arguing about what a bath or a window is worth, each person puts a price on each room. The result gives every room to someone who values it, at prices nobody envies.
Open the example