Roommate calculator
How to split rent and bills with roommates when rooms are different sizes
When one bedroom is 90 sq ft and another 150 sq ft, paying the same rent quickly feels unfair. The most common method: split part of the rent equally for the common areas, and the rest by the size of each bedroom. Bills are shared equally.
In short
- Rent is cut in two: common areas, split equally, and bedrooms, split by size.
- Formula: a roommate’s rent = (rent × common share ÷ number of roommates) + (rent × bedroom share × their room size ÷ total bedroom size).
- Example: $1,500 rent, half for common areas, rooms of 90, 120 and 150 sq ft, plus $150 of bills: $487.50, $550 and $612.50.
- Bills (utilities, internet) are usually split equally.
Work out each roommate’s share
Enter the rent excluding bills, the shared bills, the share of rent you assign to common areas, and the size of each bedroom (2 to 6 rooms). With 0% for common areas, rent is split purely by size; with 100%, everyone pays the same.
Roommate rent calculator
| Room | Rent | Bills | Total a month |
|---|---|---|---|
| Room 1 · 90 sq ft | $437.50 | $50 | $487.50 (30%) |
| Room 2 · 120 sq ft | $500 | $50 | $550 (33%) |
| Room 3 · 150 sq ft | $562.50 | $50 | $612.50 (37%) |
The method: common areas + bedroom size
Everyone uses the living room, kitchen and bathroom the same way, so it makes sense to split that part of the home equally. The roommate with the biggest bedroom, however, has more private space: that part is paid by size.
Common part = rent × % common areas ÷ number of roommates
Room part = rent × (1 − % common areas) × room size ÷ total size of all bedrooms
To pay = common part + room part + bills ÷ number of roommates
What percentage for common areas? There is no official rule. Half is a common starting point; you can also use the real proportion of the home (common-area size ÷ total size) if you know it.
Worked example
Three roommates rent a place for $1,500 a month excluding bills, plus $150 of bills. The bedrooms are 90, 120 and 150 sq ft, so 360 sq ft in total. They assign half the rent to common areas.
- Common part: 1,500 × 50% ÷ 3 = $250 each.
- Room part: $750 split by size: 750 × 90 ÷ 360 = $187.50, 750 × 120 ÷ 360 = $250, 750 × 150 ÷ 360 = $312.50.
- Bills: 150 ÷ 3 = $50 each.
Result for each roommate
90 sq ft
- Rent
- $437.50
- Bills
- $50
- Total
- $487.50
120 sq ft
- Rent
- $500
- Bills
- $50
- Total
- $550
150 sq ft
- Rent
- $562.50
- Bills
- $50
- Total
- $612.50
| Room | Rent | Bills | Total |
|---|---|---|---|
| 90 sq ft | $437.50 | $50 | $487.50 |
| 120 sq ft | $500 | $50 | $550 |
| 150 sq ft | $562.50 | $50 | $612.50 |
Total: $1,650, exactly the rent plus bills. The gap between the smallest and largest room is $125 a month, versus $0 with an equal split and $250 with a split based purely on size.
Common adjustments
- Private bathroom, balcony, better light: add a fixed premium to that room, deducted equally from the others.
- A couple sharing a room: the room part stays the same, but the common part and bills can be counted per person rather than per room.
- A roommate away part of the month: rent is usually still owed in full, but you can adjust variable shared costs like groceries.
- Actual bills different from estimates: when the final bill comes, share the extra or the refund with the same rule.
Tracking rent and shared costs
Once the rule is set, you have to stick to it: who sent the rent, who paid internet, who bought the shared groceries. Write it down, in a shared document or an app.
In SAVY, each roommate adds what they pay, and the app works out who owes whom and cuts down the number of repayments. Rent and internet can be set up as recurring expenses. On the free plan, a household has up to 4 members and expenses are split equally. Splitting rent by room size (shares or exact amounts) or having more than 4 roommates takes SAVY Plus, paid by one person and unlocked for the whole house.
Frequently asked questions
How do you split rent when bedrooms are different sizes?
Split part of the rent equally for the common areas (often half), and the rest by the size of each bedroom. Bills are usually split equally.
Should bills be split by room size too?
Usually not: utilities and internet benefit everyone equally, so they are split equally. Some households split them per person when a couple shares a room.
What share of the rent should go to common areas?
There is no official rule. Half is a common starting point; you can also use the real share of common areas in the home’s total size.
Can I split rent unequally in SAVY?
Yes, with SAVY Plus: an expense can be split by shares, percentages or exact amounts. On the free plan, each expense is split equally between the selected members.