How to split rent with roommates

The method matters less than agreeing on it before anyone signs. Here are the four that work, and the specific argument each one eventually starts.

Should roommates split rent equally or by room size?

By room size is fairer when rooms differ meaningfully: weight each room by its floor area, then adjust by hand for an ensuite, a balcony or a window onto a main road. Equal splitting is fine when rooms are genuinely comparable — and it has the large advantage that nobody has to keep agreeing to it.

The four methods

1. Equal split

Rent divided by the number of people. Works when rooms are close to identical. It's the only method that never needs revisiting, which is worth more than people expect. It breaks down the moment one room is obviously the good one.

2. By room size

Measure each private room, total the private floor area, and give each person their room's share of the rent. Shared space — kitchen, bathroom, living room — is paid for equally and stays out of the weighting.

Worked example: a €1,800 flat with rooms of 18 m², 14 m² and 10 m². The private total is 42 m², so the shares are 42.9%, 33.3% and 23.8% — €771, €600 and €429. Then adjust: if the smallest room has the only ensuite, move €40–60 back onto it and tell everyone why.

3. By income

Each person pays the same percentage of what they earn. Genuinely more equitable, and the hardest to sustain: it requires everyone to disclose income, and it has to be renegotiated whenever someone's changes. Usually only works between partners or very close friends.

4. Hybrid — room size for rent, equal for everything else

The most common arrangement in practice. Rent tracks the room; utilities, internet and shared groceries split evenly per person, because a bigger room doesn't use more electricity but a second occupant does.

The bills are where it actually goes wrong

Rent is one number, once a month, and people remember it. The failures are in the smaller flows:

Quarterly and annual bills. Log them on the day they're paid, split among whoever lived there during the period they cover. Don't wait for the settle-up to reconstruct who was around in February.
The one person whose name is on everything. Whoever holds the internet contract is effectively lending the household money every month. That's fine, as long as it's recorded as a debt rather than a favour.
Shared groceries. Either a shared pot everyone tops up, or logged per purchase. Mixing the two produces the worst outcome, which is nobody knowing what's owed.
Someone moves out mid-lease. Pro-rate by days, not by guesses about usage. Settle the full balance on the day they hand back the keys, not later.

Do it in an app, not a group chat

A recurring household is exactly the case where memory fails: the amounts are small, the frequency is high, and nobody wants to be the person bringing it up. Logging each shared cost as it happens and settling once a month turns an ongoing social negotiation into a number.

One thing to check in whichever app you choose: whether it nets debts across the whole household. Most do, which means you can be told to pay the roommate you've never bought anything with because the app saved a transfer. In a shared flat, where people already keep score, that causes more friction than the transfer it saved.Splitt keeps every balance pairwise for exactly this reason — you always pay the person you actually owe.

Frequently asked questions

Should roommates split rent equally or by room size?

By room size is fairer when rooms differ meaningfully, and the usual method is to weight each room by square metres, then adjust for features like an ensuite, a balcony or street noise. Equal splitting is fine when rooms are genuinely comparable — and it is much easier to keep agreeing to.

How do you split rent when rooms are different sizes?

Add up the total private floor area, work out each room's share of it, and apply that percentage to the rent. Then adjust by hand for anything the floor plan does not capture. Shared space is paid for equally by everyone and should not enter the weighting.

How should roommates handle utility bills that arrive quarterly?

Log each bill as a shared expense on the day it is paid, split between whoever lived there during that period, and settle monthly rather than per bill. If someone moves out mid-quarter, pro-rate their share by days rather than trying to guess usage.

Should a couple sharing one room pay more?

Two people in one room use more of the shared space, electricity and hot water than one person does, so a common compromise is to split rent by room but utilities by head. Agree it before anyone moves in; renegotiating it later is where the resentment starts.