Free tool
Flatshare rent split
To split rent between unequal rooms, first divide the rent in two: the share matching the common areas, split equally, and the share matching the bedrooms, split in proportion to their size. A 20 m² room in a flat where common areas make up half the floor space therefore does not cost twice a 10 m² room, but roughly 40 % more.
The rooms
What each person pays
- Alex-17 % vs an equal split£375.00
- Sam+17 % vs an equal split£525.00
Equal split : £450.00
- of which common
- of which room
How the calculation works
Most per-square-metre splits make the big room pay the difference twice. Here is the method that avoids it, in three steps.
1. Separate common areas from bedrooms
Rent is split in proportion to floor space: if common areas are half the flat, they account for half the rent.
2. Split common areas equally
The kitchen and living room serve the person in 9 m² exactly as much as the person in 18 m². Splitting them by bedroom size would charge the same difference twice.
3. Split bedrooms by weighted size
What remains follows each room's floor area, adjusted for its perks and drawbacks: private bathroom, balcony, no window.
Worked example
A 60 m² flat at 900 €, two bedrooms and 30 m² of common areas.
- Common areas · 30 m² out of 60, so 450 €, split equally
- 225 € each
- 10 m² bedroom · its share of the remaining 450 €, pro-rated
- 150 €
- 20 m² bedroom · its share of the remaining 450 €, pro-rated
- 300 €
- Small room : 375 €
- Large room : 525 €
A raw per-square-metre split would have given 300 € and 600 €, twice as much for the bigger room.
Key points
- No French law prescribes how flatmates split rent between themselves: the lease binds the signatories, while the internal split is a private agreement.
- Under a joint and several lease, each flatmate remains liable to the landlord for the full rent, whatever split they agreed between themselves.
- Common areas in a flatshare are split equally between occupants, because their use does not depend on bedroom size.
- A room with a private bathroom is commonly valued 10 to 15 % above a room of the same size without one.
- A room with no window cannot count as a habitable room under French decency rules, which disqualifies it as a main bedroom in a rented home.
- Habitable floor area under the French Carrez law excludes any space with a ceiling height below 1.80 metres.
- Splitting rent strictly by bedroom size charges the difference twice, once on the bedroom and once on the common areas.
Frequently asked questions
How do you work out each flatmate's rent?
Split the rent in two in proportion to floor space: the common areas and the bedrooms. Divide the first equally between flatmates, and the second in proportion to each bedroom's size. Add the two together to get each person's share.
Is it legal to charge different rents per room?
Yes. No rule requires an equal split between flatmates. The lease sets the total rent owed to the landlord; how flatmates divide it is their own agreement. Write it down, even if only in a group chat.
Does a shared bathroom count as common area?
Yes, if it is shared. Only a bathroom reachable solely from one bedroom counts as private floor space, and then justifies a premium on that room.
How much extra for a room with a private bathroom?
Ten to fifteen per cent of its weighted size is the common practice. It is not a rule, it is a figure that avoids long arguments. This calculator applies 15 %.
What if someone moves in mid-lease?
The share is worked out the same way, then pro-rated over the number of days occupied that month. Check what the lease says about joint liability and notice periods, which override any agreement between flatmates.
What about bills that do not depend on room size?
Electricity, internet or a streaming subscription do not depend on bedroom size: split those equally, separately from the rent. Do not fold them into the per-square-metre calculation.
This calculator does not replace your lease
The coefficients used here reflect common practice, not law. Under a joint and several lease, each flatmate remains liable to the landlord for the full rent, whatever split you agree between yourselves. This tool helps you reach an agreement, not change your obligations.
Rent is sorted. Now the groceries.
Once the split is agreed, the real subject becomes daily life: Saturday's groceries, the electricity bill, paying back the plumber. CountClub keeps the running tally and tells you who owes what, without a spreadsheet.
- Lasting weighted shares
- Automatic reminders
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