How much more should the master bedroom pay?
A private bathroom and roughly twice the floor area are worth something to whoever gets them. Price both openly, so nobody quietly subsidises the bigger room.
Kitchen, living room, shared bath. The rest of the rent follows each room.
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 |
|---|---|---|---|---|---|
| Master | 1 | 220 × 1.25 | $536.00 | $1,148.57 | $1,684.57 |
| Second | 1 | 110 × 1 | $536.00 | $459.43 | $995.43 |
| Total | 2 | $1,072.00 | $1,608.00 | $2,680.00 |
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
Two roommates rent a two-bedroom for $2,680. The master is 220 sq ft with its own bathroom; the second room is 110 sq ft and uses the hall bath. They treat 40% of the rent as shared space (kitchen, living room, hall bath) and split the other 60% by floor area, counting the private bath as 1.25× the area.
- Master pays $1,684.57: private bath, 1.33× average floor area.
- Second pays $995.43: 0.67× average floor area.
- Total: $2,680.00, exactly the rent.
Names and amounts are samples. Change any number in the calculator above and the result updates.
Worth agreeing in writing
Write the formula, not just the numbers, into your roommate agreement. If the rent goes up next year, the same formula gives the new split without a second argument.
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
- Both rooms are lived in the same way, so floor area is a fair proxy for how much of the flat each person really has.
- The bath multiplier is agreed out loud before anyone picks a room, not argued about after the lease is signed.
- The shared-space percentage reflects how much of the flat is genuinely common: a big living room and kitchen justify a higher share split evenly.
Not so fair when
- When the second bedroom’s occupant also has a private hall bath in practice (the master never uses it), the multiplier double-counts the master’s bathroom.
- When one room is bigger only because of awkward, unusable space (a sloped ceiling, a long corridor), raw square feet overstate its value; lower that room’s area to the usable part.
- When the person in the small room earns far less and the gap still feels heavy, a split by income may sit better than one by room. That is a values choice, not a maths error.
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
Two bedrooms, one en-suite: a fair split
The en-suite is the whole difference between these rooms for most people. Decide what it’s worth as a multiplier, and the rest follows from floor area.
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