Three real methods for splitting rent in a flatshare with unequal rooms, with worked examples and the formula nobody resents.
You've found a flat. Three bedrooms, but they're wildly different sizes - the master has a private bathroom and a window onto the garden, the second is a normal-sized double, and the third is the sort of space estate agents charitably call "a generous single". The landlord wants £2,400 a month. How do you split it?
The wrong answer is "just split it equally". The right answer takes about ten minutes and three numbers.
Use the floor-area-plus-amenities method. Each room gets a "weight" based on its size and what's in it; the rent splits proportional to the weights. We worked the maths below; pick whichever variant feels fair to your specific flat.
Measure each bedroom in square metres. Sum them. Each person's rent is proportional to their room's area divided by the total.
Worked example. Three bedrooms: 18m², 12m², 8m². Total 38m². Rent £2,400.
Sum: £2,400. Done.
This is the right starting point. It's also too crude on its own, because rooms aren't fungible by floor area. A room with a window onto a brick wall is worth less than a room with a window onto a garden, even at the same size.
Start with floor area as a base. Then add a percentage premium for each amenity:
Worked example. Same three bedrooms. Master (18m²) has en-suite (+20%) and a garden view (+5%). Middle (12m²) is unremarkable. Small (8m²) is next to the boiler that bangs at 6am (-5%).
Rent £2,400 splits to:
Sum: £2,400.
Notice the master person is now paying £146 more than the floor-area baseline, and the small-room person is paying £72 less. That gap is what the amenities are worth.
For groups that genuinely can't agree on amenity weights, there's a procedure economists love called the sealed-bid auction. Each person writes down what they'd be willing to pay for each room, on a piece of paper, without seeing each other's bids. The bids must each sum to the total rent.
Then: each room goes to whoever bid highest for it. The price they pay is their bid - or, in the more sophisticated version, an adjusted price that ensures the result is "envy-free" (no person, given the chance, would prefer somebody else's room-and-rent combination).
This is more accurate than method 2 because it captures personal preference, not just objective amenities. It's also intimidating to set up. We'd only recommend it for groups where method 2 has already produced an argument. There's a free online tool from Spliddit that runs the sealed-bid auction for you - search "Spliddit rent" if you want it.
Different question, different answer. Utilities (gas, electricity, water, internet) typically split equally, regardless of who has the biggest room. The reason: bedrooms vary enormously, but communal usage of heating, internet, and the kettle is roughly equal across people.
If one flatmate works from home and runs the heating all day while everyone else is out, that's a different conversation. We covered it in utility bills among roommates: equal vs proportional when it's out.
They're shared. Don't weight them. The reason floor area works as a baseline is precisely that we're only weighting private space.
This trips most groups up. The answer that works in practice: the couple pays the master's rent share, but split between two people. So if the master is £1,283 in the example above, each member of the couple pays £641.50. The single flatmates pay the middle (£684) and small (£433) on their own.
The single flatmate in the £684 room is now paying more than each couple-member, despite having less space. They might object. The rebuttal: a couple sharing a single room imposes no extra burden on the flat's shared resources beyond what one person would. They're also doing the smaller-room flatmate a favour by being half the bathroom traffic.
We have a longer piece on this in when a couple shares with single flatmates: rent maths when it lands.
The deposit splits in the same proportions as the rent. If you're paying 53% of the rent, you put down 53% of the deposit. When the tenancy ends, you get back 53% of whatever's left after deductions.
Cleaning fees and any landlord deductions also split in rent proportions, unless the deduction is for damage attributable to one specific person - that one's on them.
Equal split, like utilities. Council tax is per-flat, not per-room.
The single biggest predictor of whether a flat split feels fair, in our experience, isn't which method you use - it's whether everyone agreed to the method before the keys were handed over.
Sit down on viewing day. Run method 2 on the back of an envelope. Get explicit verbal agreement from everyone. Then write the numbers in the group chat. That's the contract.
Doing the conversation post-move-in, when somebody has already started unpacking into the master, is fifty times harder. It feels like renegotiation, not negotiation.
After living through five flatshare splits, the only thing we'd change is bringing a tape measure to the second viewing. Estate agents will quote room sizes, and they'll often be wrong. Measuring yourselves takes ten minutes per flat and means the rent-split conversation is grounded in numbers everyone agrees on.
Once you've agreed the proportions, set up a EvenRound group for the flat. Each person enters their share of rent on the same day each month; bills get logged as they come in and split equally. End-of-month settlement is automatic - the app tells you who owes whom.
For the rent itself, most flatmates set up monthly standing orders directly to the landlord rather than routing through one person. That's usually cleaner. The app is most useful for the rolling-balance bills and shared expenses.
Create a group for your flat - takes about twenty seconds, no signup, share the link in the flat WhatsApp.
Free forever. No signup. Works in your browser in 30 seconds.