Rent Split Calculator (By Room Size)
By Santaji GadepatilinUpdated October 27, 2026
Splitting rent fairly between flatmates often depends on room size. Dividing by area gives each person a fair share. This free rent split calculator solves for whichever value you leave blank and shows the formula and steps.
How to use the rent split calculator
Enter the total rent, the share that covers common areas (split equally) and the size of each bedroom. Each person’s share is calculated.
Rent split formula
Share = rent × common% ÷ 3 + rent × (1 − common%) × room area ÷ total room area
Example
Rent 2,400, 40% for common areas, rooms of 14, 11 and 9 m²:
- Room 1: 320 + 1,440 × 14/34 = 912.94
- Room 2: 320 + 1,440 × 11/34 = 785.88
- Room 3: 320 + 1,440 × 9/34 = 701.18
For two roommates, set one room size to 0 and adjust — or agree on the split you all find fair.
Other fair ways to split rent
| Method | How it works | Best for |
|---|---|---|
| Equal split | Total ÷ number of people | Similar rooms |
| By room size (this calculator) | Common share split equally, private share by area | Rooms of different sizes |
| By features | Add premiums for an en-suite, balcony or parking | Rooms with different amenities |
| By income | Each pays a share in proportion to income | Couples |
Adjusting for features
After the size-based split, you can move a fixed amount between rooms for extras. For example, if Room 1 has a private bathroom, it might pay 5–10% more of the rent, taken off the other rooms equally.
Couples sharing a room
If two people share one room, decide whether the room pays one share or whether common areas are split per person. Splitting common areas per person is usually fairer, since two people use the kitchen and living room more.
Bills and utilities
Electricity, internet and water are usually split equally per person, not by room size, because use depends on people. Add them separately from rent.
Put it in writing
Agree the split before moving in and write it down, including how bills are paid, what happens when someone leaves and how the deposit is shared.
Frequently asked questions
What is a fair way to split rent?
A common approach divides part of the rent equally (for shared spaces) and the rest by bedroom size.
What percentage should be for shared space?
Often 30–50%, depending on how much of the home is shared living area.
What about a private bathroom or balcony?
Add its area to that room, or agree an extra amount on top.
How do you split rent fairly with different room sizes?
Split a share of the rent for common areas equally, then split the rest in proportion to each private room’s floor area.
What share should I use for common areas?
Often 30–50%. Use more if the kitchen and living room are large and used a lot; less if people mostly stay in their rooms.