Split rent calculator
Type the monthly rent and how many of you live there. For unequal rooms, take the result into the full calculator and adjust with custom amounts.
Short answer
Equal split works when rooms and incomes are similar; otherwise weight the split by room size, by income, or by days occupied for a partial month, and use whichever method the household agrees to before signing anything.
Number of roommates
Each person pays
$0.00
- Total
- $0.00
Unequal rooms, or want to add utilities and groceries too?
Open full group expense calculatorHow it works
- 1Enter the total monthly rent.
- 2Set the number of roommates.
- 3Read the equal share per person.
- 4For unequal rooms, weight by room size or quality in the full calculator.
An equal split is the fairest starting point for most shared houses, but it breaks down once bedrooms differ noticeably in size, one person earns much more than the others, or someone moves in partway through the month. Each of those situations has a standard fix.
Room-size splits allocate rent in proportion to floor area, so a room that's 30% of the total living space pays roughly 30% of the rent. Income-weighted splits do the same in proportion to take-home pay, which is more common in couples or family arrangements than in flat-shares. Move-in proration simply charges by the day for a partial month.
Whichever method you use, agree it once, in writing, before the first payment — retrofitting a different formula after someone's paid a month at the wrong rate causes more argument than the size difference ever would.
Worked examples with real numbers
Room-size weighted rent, three tenants
Total rent is 1500 for three rooms measuring 16, 12 and 10 square metres (38 square metres total). Marco has the 16m² room, Fatima the 12m², and Ben the 10m².
| Room size and rent share | Amount |
|---|---|
| Marco's room16 m² | 631.58 |
| Fatima's room12 m² | 473.68 |
| Ben's room10 m² | 394.74 |
| Total | 1,500.00 |
| Person | Paid | Fair share | Balance |
|---|---|---|---|
| Marco | 1,500.00 | 631.58 | +868.42 |
| Fatima | 0.00 | 473.68 | −473.68 |
| Ben | 0.00 | 394.74 | −394.74 |
- FatimaMarco473.68
- BenMarco394.74
Each rent share equals room area divided by total area, times 1500 — Marco's 16/38 share works out to about 42% of the rent for the biggest room.
Move-in proration for a partial month
Rent is 1200 for a 30-day month, split equally between two existing tenants (Zoe and Priti) plus a new flatmate, Kwame, who moves in on day 16 (15 days remaining). Zoe pays the landlord the full 1200 upfront.
| Days occupied this month | Amount |
|---|---|
| Zoe30 days | 30.00 |
| Priti30 days | 30.00 |
| Kwame15 days | 15.00 |
| Person | Paid | Fair share | Balance |
|---|---|---|---|
| Zoe | 1,200.00 | 480.00 | +720.00 |
| Priti | 0.00 | 480.00 | −480.00 |
| Kwame | 0.00 | 240.00 | −240.00 |
- PritiZoe480.00
- KwameZoe240.00
Weight each person's share by days occupied out of 75 total tenant-days (30+30+15) rather than charging Kwame a full third for a half month he wasn't there.
The three formulas
1. Equal
rent ÷ number of people
2. By area
rent × (your room's m² ÷ sum of all rooms' m²)
3. By income
rent × (your income ÷ sum of all incomes)
4. By days
rent × (your days occupied ÷ sum of everyone's days occupied)
All four formulas force the shares to add back up to the total rent — check that yours do before anyone pays.
Rent-splitting methods compared
| Method | Best for | Formula |
|---|---|---|
| Equal split | Similar rooms, similar incomes | rent ÷ number of tenants |
| By room area | Noticeably different room sizes | rent × (room m² ÷ total m²) |
| By income | Couples or family households | rent × (person's income ÷ total income) |
| By move-in date | Someone joins or leaves mid-month | rent × (days occupied ÷ total tenant-days) |
Pick one method per lease term and stick to it — mixing methods mid-tenancy is the usual source of disputes.
Mistakes that cause arguments
Weighting by area but forgetting shared space
Only count private bedroom area in the ratio; splitting the lounge and kitchen by size would penalise whoever's room happens to be near them.
Re-negotiating income splits every payrise
Fix the income-based ratio for the length of the tenancy, or agree a review date — recalculating monthly turns rent into a running negotiation.
Rounding each share independently
Round the whole group's shares together so they still sum to the exact rent figure, not each one to the nearest whole number.
Practical tips
- Get room measurements from the tenancy floor plan, not guesswork — a metre either way changes the split meaningfully in a small flat.
- For income splits, use net (take-home) pay so the ratio reflects what people can actually spend.
- Agree who fronts the rent to the landlord and treat everyone else's share as a transfer to that person, not to the landlord directly.
- Store the agreed method in the group's notes or a shared doc so a new flatmate can see how they'll be charged before moving in.
Questions
- How should we split unequal bedrooms?
- Weighting by room area is the most defensible starting point; adjust for a private bathroom or balcony by a few percent.
- Should bills be included in rent?
- Keep them separate — rent is fixed and bills vary. The shared bills calculator handles the variable side.
- What about a couple sharing one room?
- Treat the room as one share and let the couple divide it between themselves.