Roommate Rent Splitter,
split rent without the drama.

Field guide

How to split rent fairly among roommates.

The most common rent-splitting method is to divide the total by the number of roommates. It is simple, fast, and almost always unfair. When bedrooms are not identical and some rooms have private bathrooms, balconies, or closets that others lack, an equal split means some people pay for amenities they do not receive. The roommate with the small box room pays exactly the same as the one with the ensuite master. That is not equal treatment; that is equal numbers masking unequal value.

A weighted rent split solves this by separating what is truly shared from what is individually owned, then pricing each portion accordingly. This calculator uses a two-pool method that is transparent, easy to explain, and defensible to every roommate at the table.

The two-pool method explained

The total monthly rent is divided into two equal pools of 50% each:

The shared pool covers common spaces: the kitchen, living room, hallways, and any shared bathrooms. These spaces belong equally to all roommates regardless of which bedroom they sleep in, so the shared pool is split equally by the number of roommates.

The room pool covers the private bedroom portion of the apartment. This is divided proportionally using a weighted score for each room, calculated from bedroom size and private amenities.

How room weights are calculated

Each room receives a base weight based on its size, then that weight is increased for any private amenities:

Once each room's weight is calculated, the weights are normalized so the room pool is distributed proportionally. A room with weight 1.20 pays a larger share of the room pool than a room with weight 0.80, in exact proportion. The calculation is:

A worked example

Three roommates sharing a $3,000/month apartment: Alex has the large master with a private bathroom, Sam has a medium room, and Jamie has a small room with a private balcony.

• Shared pool: $1,500. Split three ways: $500 each.
• Alex's room weight: 1.25 (large) + 0.15 (bath) = 1.40
• Sam's room weight: 1.00 (medium) = 1.00
• Jamie's room weight: 0.80 (small) + 0.08 (balcony) = 0.88
• Total weight: 1.40 + 1.00 + 0.88 = 3.28
• Alex's premium: (1.40 / 3.28) x $1,500 = $640
• Sam's premium: (1.00 / 3.28) x $1,500 = $457
• Jamie's premium: (0.88 / 3.28) x $1,500 = $402

Final payments: Alex pays $1,140, Sam pays $957, Jamie pays $902. Total: exactly $3,000. Everyone understands the logic, and no one feels they are subsidising someone else's amenities.

Why the 50/50 split between shared and private

The 50/50 allocation is a practical starting point that works well for most apartments. In a typical urban flat, roughly half the livable area is shared space (kitchen, living room, bathrooms, corridors), and half is private bedrooms. Anchoring the split at 50/50 ensures that even the smallest bedroom still benefits meaningfully from shared spaces they help pay for, while the largest bedroom is not inflated beyond what the bedroom itself is worth.

Some roommates prefer a 60/40 or 40/60 ratio depending on whether the apartment skews toward larger or smaller common areas. The key is agreeing on the ratio before the lease is signed, not renegotiating it mid-tenancy.

When to use a different method

The weighted method works best when bedrooms are genuinely different in size or amenities. If every room is identical, a simple equal split is mathematically equivalent and easier to communicate. The weighted method also assumes that the named amenities (bathroom, balcony, closet) are exclusive to one roommate. If a balcony is technically private but roommates share it informally, its premium weight can simply be left unchecked.

For situations where one roommate works from home and uses shared spaces significantly more, or one person's partner effectively lives there part-time, the weighted method can be adjusted by conversation but not by formula. Those cases require negotiation, not calculation.

Disclaimer

This calculator provides a suggested fair split based on a standard weighted method. Actual rent agreements should be discussed and agreed upon by all parties. Consult your lease terms and any applicable tenancy regulations in your jurisdiction.