Rent and electricity arrive as one bill. Toilet paper, dish soap and olive oil arrive as twenty small receipts, bought by whoever happened to be at the shop. That is why this is the part of shared living that quietly breeds resentment.
A simple rule fixes most of it.
Sort purchases into three piles
Personal. Snacks, drinks, special diets, your own toiletries. You buy it, you own it, nobody splits it.
Shared supplies. Things everyone uses and nobody thinks about: toilet paper, dish soap, bin bags, sponges, cleaning spray, kitchen roll. Split these equally.
Shared food. Pantry staples everyone uses (oil, rice, salt) can go in the shared pile. Meals cooked together are split only among the people who ate.
When a receipt mixes piles, take out the personal items first and split what is left.
Two ways to keep it simple
The running tally. Whoever buys shared supplies keeps the receipt or photographs it. At the end of the month, add up what each person spent, divide the total by the number of roommates, and settle the difference.
The rotating buyer. One person buys the supplies for a month, then the next. Over a few months it roughly evens out, and you only settle up when someone leaves or the gap gets big.
The tally is more exact. Rotation is less admin. Pick one and write it in the group chat.
Worked example (illustrative numbers)
Three roommates, one month of shared supplies.
- Ana did a big shop for $80, but $20 of it was her own snacks. Shared part: $60.
- Ben bought cleaning supplies and toilet paper for $36.
- Cam bought nothing this month.
Shared total: $60 + $36 + $0 = $96. Equal share: $96 / 3 = $32 each.
| Spent on shared | Fair share | Difference | |
|---|---|---|---|
| Ana | $60 | $32 | +$28 (is owed) |
| Ben | $36 | $32 | +$4 (is owed) |
| Cam | $0 | $32 | -$32 (owes) |
Cam pays $28 to Ana and $4 to Ben. The owed amounts ($28 + $4) equal what Cam owes ($32). These numbers are made up; swap in your own.
Set a few boundaries up front
- A price ceiling. Agree a rough limit for shared items, so nobody has to subsidise a premium brand.
- Shared means shared. If something is for everyone, it goes on the tally. If it only fits one person's taste, it is personal.
- Speak up in the month. Raising a gap after six months is much harder than after one.
Do the math faster
For the equal split, the utility bill splitter works too: enter each person's shared spending as a bill, split equally, and read off who owes what. Free, no signup.
FAQ
Do we split alcohol and snacks? Usually not. Treat them as personal unless everyone drinks or eats them and you agreed to share.
What if one roommate eats much more of the shared food? Move shared food into a smaller pile, split only among the people who eat it, or agree a small fixed extra. Keep the rule simple enough to follow.
What about a roommate who is away for weeks? For supplies they don't use, it is fair to pause their share. Agree this before they leave.
Stop keeping receipts in your phone
Billmates is a web app, still on the waitlist, that tracks who owes what in a shared home. It never holds or moves your money. You pay each other the way you already do. Roommates join from a browser link. No ads. If you'd like to hear when it's ready, leave your email below.