How to split rent fairly
Four methods used by actual roommates, with worked examples and the math spelled out. Pick one before you sign the lease and you'll avoid the single most common source of house-share friction.
- Equal split — simplest, works if rooms are similar
- By room size — fairest when bedrooms differ a lot
- By income — progressive, when incomes differ a lot
- By move-in date — for partial-month arrivals
Method 1 — Equal split
Everyone pays the same share: rent ÷ number of roommates.
Works when the bedrooms are genuinely comparable (same floor, similar
size, same closet situation). Fails when one person has the master
bedroom with en-suite and another has a converted storage closet.
Example: €1,800 rent, 3 roommates → €600 each.
Method 2 — By room size (square-footage)
Each roommate's share is proportional to their bedroom's area as a fraction of total bedroom area.
Formula: (your room area ÷ sum of all room areas) × rent.
Example: €1,800 rent. Three bedrooms measuring 18 m², 14 m², and 12 m² (total 44 m²):
| Room | Area | Share of total | Monthly rent |
|---|---|---|---|
| Master (Alice) | 18 m² | 40.9 % | €736 |
| Medium (Bob) | 14 m² | 31.8 % | €573 |
| Small (Carol) | 12 m² | 27.3 % | €491 |
Refinement: if one room has a private bathroom or a balcony, add a fixed €50–€100 "amenity premium" for that room before applying the split. Measure tape + a shared note pinned in the kitchen keeps this honest.
Method 3 — By income
Each roommate's share is proportional to their gross monthly income as a fraction of total household income.
Formula: (your income ÷ sum of all incomes) × rent.
Example: €1,800 rent. Three roommates earning €4,000, €2,500, and €1,500 gross/month (total €8,000):
| Roommate | Gross income | Share of total | Monthly rent |
|---|---|---|---|
| Alice | €4,000 | 50.0 % | €900 |
| Bob | €2,500 | 31.3 % | €563 |
| Carol | €1,500 | 18.8 % | €338 |
This method requires a certain level of trust — everyone has to share real income figures. It's more common among couples and long-term close friends than among fresh-off-Craigslist housemates.
Method 4 — By move-in date (prorating)
If a roommate moves in mid-month, their first month is prorated:
(days in the apartment ÷ days in the month) × their normal share.
Example: Bob normally pays €600 and moves in on the 18th
of a 30-day month (so he's there for 13 days). First-month rent =
(13 ÷ 30) × 600 = €260.
Utilities and shared bills
Don't fold utilities into the rent split. Keep each as a separate line item: electricity, internet, water, streaming. Most groups split utilities equally even when they split rent by room size or income — usage variance is smaller than it looks, and equal utility splits cut the accounting overhead in half.
Exceptions worth discussing upfront:
- A roommate working from home full-time may fairly cover more of the electric / heat bill.
- A roommate who pays for a family Netflix plan isn't adding it to the shared bill.
- Long-absent roommates (travel, visiting parents for a month) — decide upfront whether they still owe their full share for fixed costs.
How Monkey Split helps
Whichever method you pick, you still have to log it, track it, and settle it every month. Monkey Split is a free group expense app that makes this painless:
- Recurring expenses — set rent once; each month it projects the next one for you to confirm with one tap.
- Weighted splits — encode room-size or income shares once and reuse them every month.
- Categories and tags — keep rent separate from utilities, groceries, and shared furniture so you can see exactly where your housing money goes.
- Optimal settle-up — end-of-month, one algorithm collapses all the debts into the minimum number of transfers.
- Free — no ads, no paywall, no tracking.
FAQ
What's the single fairest method?
There isn't one. The fairest method is whichever one all roommates agree to before move-in. Room-size splits favour the person with a small room; income splits favour the lower earner; equal splits favour whoever got the master bedroom. Pick openly, not by default.
What about deposit splits?
Deposits are usually split the same way as rent, because everyone
forfeits their share if you collectively trash the place. Track each
person's deposit contribution as a one-off expense tagged
deposit so it's clear what each person is owed back when
they move out.
How do you handle a roommate who refuses to pay?
In the short term: a shared app with a clear running balance makes it harder to deny the math. In the long term: a written housemate agreement referencing the split method and consequences for missed payments. If it goes legal, the landlord typically treats all tenants as jointly-and-severally liable — meaning one person missing their share becomes everyone's problem.
Do I need an app, or is a spreadsheet fine?
A spreadsheet works. It just doesn't survive the second roommate. A shared app syncs across phones, handles the math automatically, and gives you a settle-up button instead of another 10 minutes of copy-pasting Venmo usernames.