Roommate expenses
Sharing a home means sharing the largest bills most people pay. A roommate expense system has one job: make it obvious, every month, who has paid what — without anyone having to ask.
Why household costs are worth tracking properly
Housing is the single largest category of household spending. In the UK, housing, fuel and power came to an average of £118.40 a week in the financial year ending 2025 — 18% of the £676.60 an average household spent weekly.[1]
Split three ways and paid by whoever's name is on the account, that is a large, recurring, uneven flow of money between people who also have to live together. It is the case where an accurate record matters most and where informal memory fails fastest.
Setting it up once
- Create a group of type Home and name it after the address, not the people — housemates change, the flat does not.
- Add everyone who lives there. Invite by email or phone if they are not on Expenddy yet.
- Agree the rent split before the first month, and write it down as percentages if it is not even.
- Decide what counts as a shared cost. Rent and utilities always are; groceries and cleaning supplies are the ones worth deciding explicitly.
- Agree a settle-up day — the same date each month works better than 'when we get round to it'.
Which split method for which cost
| Cost | Split method | Why |
|---|---|---|
| Rent, rooms of equal size | Equal | Nothing to decide; the amount rarely changes. |
| Rent, rooms of different sizes | Percent | Set the ratio once — say 40/35/25 — and it applies to every future rent payment automatically. |
| Energy, water, internet | Equal, or percent if agreed | The amount changes every bill; the fairness rule does not. A percentage split survives the change. |
| Council tax or local property tax | Equal, or percent | Same reasoning as rent. If one person has a discount or exemption, use exact amounts. |
| Shared groceries | Equal | Averages out quickly. Use exact amounts only when someone's own items are on the same receipt. |
| A subscription only some people use | Equal, between those people | Change who is included rather than adjusting percentages. |
Worked example: three housemates, one month
A month in a three-bedroom flat
Ren has the largest room and pays 40% of rent; Kit and Ivy pay 30% each. Rent is £1,500. The energy bill of £96 and broadband of £33 are split equally. Ren pays the rent and the broadband; Kit pays the energy bill. Ivy bought £45 of shared cleaning supplies and cat food.
| Expense | Amount | Paid by | Split | Ren | Kit | Ivy |
|---|---|---|---|---|---|---|
| Rent | £1,500 | Ren | 40 / 30 / 30 | £600 | £450 | £450 |
| Energy | £96 | Kit | Equal | £32 | £32 | £32 |
| Broadband | £33 | Ren | Equal | £11 | £11 | £11 |
| Shared supplies | £45 | Ivy | Equal | £15 | £15 | £15 |
| Total owed | £1,674 | — | — | £658 | £508 | £508 |
Result: Ren paid £1,533 and owes £658, so is owed £875. Kit paid £96 and owes £508, so owes £412. Ivy paid £45 and owes £508, so owes £463. Kit and Ivy each make one transfer to Ren, and the month is closed.
Two transfers, no arithmetic, and every figure traceable to an expense somebody entered. Compare that with the usual approach: four separate “can you send me your share” messages, each one calculated by hand.
The cases that break naive systems
The bill is in one person's name
Almost always true of energy, water and broadband. That person is structurally the creditor: they are out of pocket from the day the direct debit leaves until everyone pays them. Recording the bill the day it is paid, rather than at the end of the month, keeps that visible.
Someone moves in or out mid-month
Use an exact-amount split for that month only, calculated pro rata by days, then return to the normal split afterwards. Record it in the expense description so the odd figure makes sense to whoever looks at it later.
Groceries that are partly personal
The most common source of low-grade friction in a shared house. Two workable approaches: split the whole shop equally and accept it averages out, or use an exact splitwith each person's own items separated out. Pick one and stick to it — alternating is what causes arguments.
Someone consistently falls behind
A shared ledger changes this conversation. Instead of one person making an accusation from memory, everyone can see the same balance. That is usually enough, and it removes the need for anybody to play the role of debt collector.
Settling monthly
Pick a date — payday, or the day after rent leaves — and settle then. Each person pays what they owe and records the payment; balances return to zero and the next month starts clean.
Households that never settle end up with balances so large that clearing them becomes its own difficult conversation. Monthly settlement keeps the numbers small enough to be uncontroversial.
If you want a record outside the app — for a tenancy dispute, or just for your own files — the group ledger exports to CSV.
Roommate questions
Can I use Expenddy with roommates?
Expenddy works for roommates and flatmates sharing a home. Create a group of type Home, add everyone living there, and record rent, utilities, the internet bill and shared groceries as they are paid. Recurring costs with a fixed ratio can be split by percentage, one-off shared items equally, and anything only some people share can be split between just those people.
Can Expenddy split an expense by percentage?
Expenddy supports percentage splits. You assign each person a percentage of the total, the percentages must add up to 100%, and Expenddy converts them into currency amounts. This suits costs where the ratio stays the same but the amount changes each month, such as rent split 60/40 by room size.
Can Expenddy track who owes whom?
Tracking who owes whom is Expenddy's main function. Every expense updates a running balance for each member, and each group shows what you owe and what you are owed, broken down per person. Balances recalculate whenever an expense is added, edited or deleted.
Can I get my data out of Expenddy?
Expenddy exports to CSV. A group's full ledger can be exported from the group's settings, a friend ledger from that ledger's screen, and your personal records from the personal section. The file opens in any spreadsheet program.
Sources
- Family spending in the UK: April 2024 to March 2025. Office for National Statistics, published 11 June 2026 — housing (net), fuel and power averaged £118.40 per week, 18% of average total weekly household expenditure of £676.60
External statistics above are published by the organisations named and are not Expenddy data. Statements about how Expenddy works describe the app itself.
Set up your household group
Record a shared expense, see the balance update, and settle it when the money moves.
Free to use. Available for Android and in any web browser. An iOS app is in development and is not released yet.