About the Rent Split Calculator
This rent split calculator divides rent between two, three or four roommates in a way everyone can check. The default method charges each person for the square footage of their own bedroom and splits the shared space — kitchen, living room, hallways — equally, so the person with the biggest room pays a little more and nobody subsidises anyone else.
You can also add a monthly premium for rooms with a private bathroom (or another perk such as a balcony or parking spot). The premium is paid by those roommates and taken off the amount everyone else splits, so the total always adds up exactly to the rent. Utilities are divided evenly on top.
If your rooms are about the same size, switch to an equal split. Measure rooms length × width in feet and use the apartment’s total square footage from the listing; if the rooms add up to more than the listed total, the calculator treats the rooms as the whole apartment.
With the default inputs, the roommate 1 pays is $1,102.92. Change any value above to recalculate instantly.
How to use the rent split calculator
- 1Enter the total monthly rent and the shared utilities.
- 2Choose the number of roommates and the split method.
- 3Enter the apartment size and each bedroom’s square footage.
- 4Set a premium and tick who has a private bathroom or other perk.
- 5Review each roommate’s share and the breakdown table.
Formula and method
First, the bathroom premiums are set aside: each roommate with a private bath pays the premium, and the rest of the rent (B) is what gets split. In the size-based method, B is divided by the apartment’s total square footage to get a rent per square foot. Each person pays that rate for their own bedroom, and the rent for the shared area (total minus all bedrooms) is split equally among the k roommates.
In the equal method, B is simply divided by the number of roommates. Utilities are always split evenly. Because every dollar of rent is assigned to a bedroom, the shared space or a premium, the shares always add up to the total rent plus utilities.
- B
- Rent left after bathroom premiums
- k
- Number of roommates
- room
- A roommate’s bedroom size in sq ft
- shared
- Total sq ft minus all bedrooms
Worked examples
Three roommates, one with a private bath
The $75 bathroom premium comes off first, leaving $2,625 to split, or $2.1875 per sq ft of the 1,200 sq ft apartment. The 760 sq ft of shared space costs $554.17 each. Roommate 1 pays $393.75 for a 180 sq ft room plus the shared share, the $75 premium and $80 utilities: $1,102.92.
Two roommates, different room sizes
$2,400 over 1,000 sq ft is $2.40 per sq ft. The 680 sq ft of shared space costs $1,632, or $816 each. Roommate 1’s 200 sq ft room adds $480 for a total of $1,296; roommate 2’s 120 sq ft room adds $288 for $1,104.
Four roommates, equal split with two private baths
Two $50 premiums leave $3,500, which splits into $875 each. Roommates with a private bath pay $925 and the others $875, and everyone adds $75 of utilities, giving $1,000 and $950.
Frequently asked questions
What is the fairest way to split rent?+
A common fair method is to split shared space equally and charge each person for the size of their own bedroom, then add agreed premiums for perks like a private bathroom. It is transparent, easy to verify and always adds up to the full rent.
How do you split rent when one room has a private bathroom?+
Agree on a monthly premium for the private bathroom — often somewhere around $50–$150 depending on the market — charge it to that roommate, and split the remaining rent between everyone. This calculator does that automatically.
Should the person with the bigger room pay more?+
Usually yes. A bigger bedroom is more private space, so charging by square footage for bedrooms while sharing the common areas equally is widely seen as fair. If the rooms are close in size, an equal split is simpler.
How should roommates split utilities?+
Most roommates split utilities evenly because usage is hard to measure per person. If one person works from home or uses much more power, you can agree on a larger share for them.
What if the room sizes add up to more than the apartment size?+
That usually means the listing size is wrong or the rooms were measured generously. The calculator then treats the bedrooms as the whole apartment, so rent is split purely by room size with no shared-space share.