How to Split Rent by Square Footage (With a Worked Example)

An even split is the simplest way to divide rent, and the one most likely to cause resentment when one roommate has a bedroom twice the size of another. Splitting by square footage fixes that, but a pure square-foot split has a flaw: everyone uses the kitchen and living room equally. Here's a method that handles both.

The simple version: split by bedroom size only

Take a three-bedroom apartment at $3,000 a month with bedrooms of 200, 150 and 100 square feet. The bedrooms total 450 square feet.

• 200 sq ft is 44.4% of the bedroom space, or $1,333
• 150 sq ft is 33.3%, or $1,000
• 100 sq ft is 22.2%, or $667

This works, but it asks the person in the smallest room to pay for a much smaller share of the shared space than they actually use.

The fairer version: shared spaces split equally

Decide what part of the rent covers common areas. Our calculator assumes 40%, which you can treat as a starting point for the conversation. On the same $3,000 apartment:

• Shared areas: 40% of $3,000 is $1,200, or $400 each
• Bedrooms: the other $1,800, divided by size

Bedroom	Shared share	Bedroom share	Total
200 sq ft	$400	$800	$1,200
150 sq ft	$400	$600	$1,000
100 sq ft	$400	$400	$800

The gap between the biggest and smallest room shrinks from $666 to $400, which most roommates find easier to accept.

What to adjust for besides square footage

• Private bathroom. A room with its own bath is worth more than the same size room that shares one. Add a percentage premium to its weight.
• Closet, light and noise. A walk-in closet, a window onto a quiet side of the building, or a balcony all have value even if they add no square feet.
• Parking and storage. If only some roommates use them, charge for them separately instead of folding the cost into rent.
• Utilities. Split utilities equally unless one person's use is clearly different, for example a home-based job.

Put it in writing

The split between roommates is separate from what you each owe the landlord. If you're all on one lease, the landlord can ask any of you for the full rent, so a written agreement is your protection against a roommate who stops paying. See the roommate agreement builder and the dictionary entry on joint and several liability.

To skip the math, enter your rent and room sizes in the rent split calculator and send the link to everyone.