Guide
Splitting expenses with roommates
In a flatshare the difficulty is not the amount, it is the repetition. The same costs come round every month with small variations — someone away, a settlement bill, a shared purchase — and nobody wants to spend an evening on it.
Rent: one key, decided once
Unequal rooms justify unequal rent. One possible key is floor area: a 16 m² room pays more than a 10 m² one. Other criteria can be added — a balcony, an en-suite, a dual-aspect room — as long as they are settled on day one and written down.
Reopening the rent key every quarter is the fastest way to poison a flatshare. Once agreed, it should only change when a flatmate or the tenancy changes.
Shared bills versus personal spending
Shared costs pass a simple test: would this expense exist even if one flatmate did not? The broadband contract, yes — it is shared. A beer bought by one person, no.
The genuine grey area sits between the two: groceries. The compromise that survives longest is to pool a short list of basics and leave everything else personal, rather than trying to split every receipt line by line.
Example: three flatmates, one away for ten days
| Line | Amount | Key | Split |
|---|---|---|---|
| Rent | £1,050.00 | Area 16 / 12 / 10 m² | £442.10 / £331.58 / £276.32 |
| Electricity | £96.00 | Days present 30/30/20 | £36.00 / £36.00 / £24.00 |
| Broadband | £29.99 | Equal shares | £10.00 / £10.00 / £9.99 |
| Cleaning products | £42.50 | Equal shares | £14.17 / £14.17 / £14.16 |
Rent follows floor area (38 m² total): 1,050 × 16 / 38 = £442.105…, truncated to £442.10; the two leftover pennies go to the largest remainders (12 m², then 10 m²), exactly as Pivunio does, and the three shares add back to £1,050.00. Electricity follows the 80 person-days in the month. Leftover pennies are assigned to named people so every line adds back to its exact amount.
What to agree before moving in
Four questions prevent most disputes: which key for rent, what counts as shared groceries, how long absences are treated, and what happens to a shared purchase when its buyer moves out. Answering them takes fifteen minutes at the start and saves months of unspoken resentment.
A fifth point can be overlooked: which day of the month do you settle? A fixed date — the 5th, say — turns the whole subject into a two-minute formality.
Frequently asked questions
Should groceries be shared?
It depends how you live. If you cook together, a shared grocery pot is simpler and fairer. If everyone eats separately, share only genuinely common items — loo roll, cleaning products, coffee — and leave the rest personal.
What about a flatmate away for a whole month?
Rent is still owed: the room is being held for them. Consumption-driven costs like electricity, water and shared groceries can reasonably be split by days actually present.
Who pays when a shared appliance breaks?
Something that benefits everyone and stays in the flat is shared between the flatmates living there at the time. Agree in advance what happens to the item when the person who paid moves out — that question can become a source of end-of-tenancy arguments.
Editorial review — Written and reviewed by the Pivunio team. The methods described here are the ones the app itself uses, and they are covered by automated tests.