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Shared house expenses: rent, utilities and groceries
A shared house is not a trip: the costs come back every month, indefinitely. A rough arrangement that survives three weeks among friends becomes unbearable over two years. Here is how to split rent when the bedrooms are unequal, what genuinely belongs in shared costs, and how to settle each month without chasing anyone.
The short answer
Three categories, three treatments. Rent is split by private bedroom size, with the shared areas divided equally. Utilities (power, water, internet, insurance) are split equally: nobody can measure their individual wifi consumption. Shared groceries are logged as they happen and settled once a month.
The rule that prevents conflict isn't a calculation rule at all: it's a fixed monthly settle-up date, the same every month, that nobody has to ask for.
Rent: equal shares or by room size?
Equal shares is the default, and it's fair when the bedrooms are comparable. The moment a size difference exceeds about 20%, it stops being fair — and that is the most common unspoken resentment in a flatshare.
The most balanced method splits rent in two: a portion for the shared areas, divided equally, and a portion for the private bedrooms, allocated by floor area. A 60% bedrooms / 40% shared split is a reasonable match for how a house actually gets used.
Example: $2,100 across three unequal bedrooms
Bedrooms of 160, 130 and 100 sq ft — 390 sq ft private in total. Split the rent: $1,260 for bedrooms, $840 for shared areas.
| Housemate | Bedroom | Room share | Common share | Rent |
|---|---|---|---|---|
| Camille | 160 sq ft | $517 | $280 | $797 |
| Nadia | 130 sq ft | $420 | $280 | $700 |
| Arthur | 100 sq ft | $323 | $280 | $603 |
| Total | 390 sq ft | $1,260 | $840 | $2,100 |
Split equally, everyone would pay $700. Nadia pays exactly the same either way, Arthur saves $97 a month and Camille pays $97 more — $1,164 of difference over a year. That's the order of magnitude that justifies spending ten minutes on it when you move in.
Other factors can be weighed alongside floor area: a private balcony, an en-suite bathroom, light, a top floor with no elevator. The principle is the same — weigh them once, in writing, at the start.
Utilities: what actually gets shared
| Item | Split | Note |
|---|---|---|
| Electricity, gas | Equally | Unless heating is metered per room, which is rare |
| Water | Equally | — |
| Internet | Equally | Including for whoever is rarely home: the bill is fixed |
| Renter's insurance | Equally | Check every occupant is actually named on it |
| Cleaning supplies, paper goods | Equally | Simplest: one person buys, it gets logged |
| Streaming subscriptions | Equally, between subscribers only | Rarely everyone: treat as an expense split between selected people |
| Groceries | Depends on the setup | See below |
The case that comes up most: a housemate away half the month asks for a discount on utilities. On electricity the argument has some merit; on internet and insurance, none at all — they're fixed costs. The workable answer is to keep everything equal and say so on day one. Prorating by presence turns every month into a negotiation.
Groceries: three possible setups
1. Fully shared food
Everyone eats everything, one person shops, the receipt gets logged, and it settles at month end. It's the simplest and most sociable arrangement. It assumes similar eating habits — a particular diet or a very different budget makes it unfair fast.
2. Shared staples, personal food separate
Only shared basics go in the pot: oil, coffee, toilet paper, cleaning supplies. Everything else is individual. This is the most common setup in long-term flatshares, because it requires nobody to arbitrate anything.
3. Everyone for themselves
No shared shopping at all. Simple, but it loses the bulk-buying savings and puts three half-used bottles of oil in the cupboard.
Whichever setup you pick, log the amount when it's paid, not at the end of the month. A receipt found three weeks later is a receipt nobody claims.
A permanent group for the house
Recurring costs like rent or the internet bill get added automatically each month. Everything else takes ten seconds to log, and the monthly reckoning is ready without anyone preparing it.
Create the house groupThe monthly routine that works
- A fixed date. The 1st or the 5th, always the same. What makes money reminders awkward is that they're exceptional; a recurring appointment makes them routine.
- One person handling rent, if the lease requires it — but the others pay them back the same day, not "sometime this week".
- A netted settlement. Don't repay expense by expense: settle net positions. Among three housemates that's usually one or two transfers instead of six.
- A history anyone can look at, so nobody has to rely on their memory, or argue about it.
The situations that cause trouble
Someone moves out mid-month
Rent and utilities are prorated by days. What resolves badly isn't that calculation but the security deposit: the landlord only returns it at the end of the lease, often long after the person has gone. The healthiest practice is for the replacement to buy out the leaver's share on arrival, rather than waiting for the return.
Damage and the deposit
Damage attributable to one person is theirs; normal wear is shared. Photos at move-in and move-out prevent any argument, and a detailed inventory beats any verbal agreement.
The guest who stays three weeks
It isn't primarily a money issue, but it becomes one on power and shared groceries. Agreeing a threshold in advance — beyond so many nights a month, an extra share on utilities — beats improvising a rule mid-conflict.
In short
- Rent by room size, shared areas equally: the most defensible approach once the rooms differ.
- Utilities equally, with no presence prorating: the costs are fixed and the exceptions unmanageable.
- Pick a grocery setup and stick to it; log at the moment of payment.
- A fixed settle-up date every month, and netted transfers.
- Put the rules in writing when you move in, while everyone is still in a good mood.