Quick tip: Takes about two minutes—enter rent and rooms, describe each room, then adjust what matters most.
RoomieMath — fair roommate rent split calculator
Unequal rooms shouldn’t mean awkward guesses. Answer a few questions, tune what “fair” means to your household, and get a clear split you can share with housemates. Built for UK shared homes; works with GBP or any currency you enter.
Your rent & rooms
Enter the total rent, how many bedrooms you’re splitting, and how you want to describe room size (total area or two side lengths).
In the next step, enter total floor area for each room in m².
Describe each room
For sliders, 1 is worst in the house for that factor and 5 is best—only differences between rooms change the rent.
Room 1 of 3
Room 2 of 3
Room 3 of 3
What matters most?
Drag right if that factor should pull rent more when rooms differ. Set to 0 to ignore a factor entirely.
Your split
For discussion only — not legal or financial advice.
- Room A
Mostly driven by private bathroom and room size.
942.35(39.3% of total) - Room B
Mostly driven by room size and natural light.
700.36(29.2% of total) - Room C
Mostly driven by room size and natural light.
757.29(31.6% of total)
Done — your shares add up to the total rent.
Each room’s share is proportional to a score built from your inputs. Attributes are normalized within the household (e.g. the largest room scores 100% on size), then multiplied by the importance sliders below. Your weights—not the app—decide what “fair” means.
Rounded to the nearest cent; leftover cents go to the room(s) with the largest fractional shares so the total matches your rent exactly.
Why each room’s score looks like this
Each coloured segment is that factor’s share of the room’s total score (not rent %).
- Size
- Bath
- Light
- Floor
- Store
- Extras
Plain-language summary
Each room’s share is proportional to a score built from your inputs. Attributes are normalized within the household (e.g. the largest room scores 100% on size), then multiplied by the importance sliders below. Your weights—not the app—decide what “fair” means.
Room A pays more than Room B mainly because of differences in: private bathroom, room size. If that doesn’t match how your household values those perks, move the importance sliders until the split feels right—that’s the negotiation baked in.
Cents are allocated proportionally, then any rounding remainder is assigned to the rooms with the largest fractional shares so the column always adds up to your total rent.
Your numbers go into the link—no account. Anyone with the link can open the same scenario.
Common questions
Do I need to sign up?
No. RoomieMath runs in your browser. There is no account, password, or database of your household on our servers.
What currency does it use?
You enter rent in whatever currency you use (for example GBP). The tool just splits numbers and formats them with your browser’s locale—no forced exchange rates.
Is this legal or financial advice?
No. RoomieMath is a calculator to help you agree on a split. It is not legal, tax, or financial advice. If your tenancy or deposit rules require a specific method, follow those or speak to a qualified professional.
Where is my data stored?
Inputs stay on your device unless you use “Share link,” which copies the state into the URL so others can open the same scenario. We do not require a login. See our Privacy page for details.