Two people in one bedroom, one person in each of the others. Do you split the rent by room, or by head? Split by room and the couple gets housing at half price each. Split by head and the couple pays two-thirds of a flat where they occupy one bedroom. Neither is right on its own.
The fix is to stop treating it as one calculation.
Want the numbers instantly? Use our free bill split calculator to compare an income-based split with 50/50 in euros.
Step 1: split the rent between rooms
First, work out what each room costs, ignoring how many people sleep in it. Use floor area, the way you would in any flatshare — see splitting rent by room size for the formula.
Then add a shared-space premium to the couple's room. This is the part people skip, and it's the part that makes the arrangement fair: two people use more of the kitchen, bathroom, living room, hot water, washing machine and hallway than one person does.
Common approaches to the premium:
- A flat amount: €50 to €150 a month added to the couple's room, depending on the flat and the rent level.
- A partial head count: count the couple as 1.5 people when dividing the shared-space portion of the rent.
- Utilities only: keep rent purely by room, but split utilities per person so the couple covers two shares. Simple, and often enough in flats with modest bills.
Step 2: split the couple's share between the partners
Once the couple knows what their room costs, that number is a private matter between them. They can split it evenly, or proportionally by income if they earn different amounts — the roommates don't need to be involved, and the couple's internal arrangement shouldn't change what the flat receives. If incomes differ, splitting by income is the usual choice.
Worked example
A three-bedroom flat at €1,950. Bedrooms are 20 m² (the couple), 13 m² and 12 m² — 45 m² of private space. The flat agrees a €120 shared-space premium for the couple's room.
| Room | Area | Share of private space | Area-based rent | Premium | Pays |
|---|---|---|---|---|---|
| Couple's room | 20 m² | 44.4% | €867 | +€120 | €987 |
| Roommate 1 | 13 m² | 28.9% | €563 | −€60 | €503 |
| Roommate 2 | 12 m² | 26.7% | €520 | −€60 | €460 |
| Total | 45 m² | 100% | €1,950 | €0 | €1,950 |
The couple then divides their €987. If they take home €2,800 and €1,900, an income-weighted split gives €587 and €400. If they split evenly, it's €493.50 each.
Note that the premium nets to zero across the flat — every euro added to one room is deducted from the others, so the landlord still receives exactly the rent.
Put it in writing
This is the arrangement most likely to go wrong six months in, because it has the most moving parts and the most room for private grievance. Write down four things in a shared note:
- What each room pays, and the premium figure.
- How utilities are split — per person or per room.
- The monthly settle-up date.
- What happens if the couple breaks up or one partner moves out.
That last point matters more than it feels like it does. If the couple's room suddenly holds one person, does the premium disappear? Agree the answer while everyone is on good terms.
Frequently asked questions
Is a shared-space premium actually fair?
Yes. Rent buys private space and shared space, and the shared half is consumed per person. Charging only by room means the roommates subsidise the couple's use of the common areas.
How much should the premium be?
Enough that the roommates don't feel squeezed and small enough that the couple isn't paying for a second bedroom they don't have. A reasonable guide is roughly half of what a per-person split would add.
Should utilities be split per person or per room?
Per person. Energy, water and internet use scales with people, not doors.
What if a partner moves in mid-tenancy?
Renegotiate before they move in, not after — and check the lease, since many tenancy agreements require the landlord's written consent for an additional occupant.
Should the couple be on the lease as one tenant or two?
Two, where possible. It protects each partner's independent standing if the relationship ends.
One shared ledger, two layers of splitting
SharedNest handles custom shares per person, so a couple can track the flat's bills with their roommates and split their own portion between themselves — with private expenses that stay private. Start free while we're building.
Related: splitting rent with roommates fairly
