Bedrooms in a rental apartment are rarely identical. One bedroom may be bigger. One may have better lighting. One might have an en-suite bathroom or a private balcony.
If you are renting a $2,000/month apartment, and your roommate gets a 200-square-foot master suite with a private bath while you get a 100-square-foot converted office, splitting the rent $1,000 / $1,000 is hard to defend. You are subsidizing their extra space.
Here is a math-based way to work out how much each roommate could pay based on room size and amenities.
The Square Footage Method
A straightforward way to split rent is to calculate the price per square foot of the bedrooms. It gives you numbers to discuss instead of feelings.
Step 1: Calculate the Common Area Rent
Let's assume your total rent is $2,000. Common areas (living room, kitchen, shared bathrooms) make up 50% of the apartment's value, and the private bedrooms make up the other 50%.
Therefore, the common area costs $1,000. You divide this equally among all roommates. In a two-person household, you each pay a base rate of $500.
Step 2: Calculate the Private Bedroom Rent
The remaining $1,000 is distributed based on the size of the bedrooms.
Let's say the Master Bedroom is 200 square feet, and the Small Bedroom is 100 square feet. The total bedroom space is 300 square feet.
Divide the $1,000 by 300 sq ft = about $3.33 per square foot.
- Master Bedroom Cost: 200 sq ft * $3.33 = about $667.
- Small Bedroom Cost: 100 sq ft * $3.33 = about $333.
Step 3: The Final Rent Bill
- Roommate in Master: $500 (Base) + $667 (Room) = $1,167
- Roommate in Small Room: $500 (Base) + $333 (Room) = $833
In this example, the person in the smaller room pays about $334 less per month than the person in the master.
The Amenity Adjustments
Square footage doesn't tell the whole story. A smaller room with a private bathroom is often more valuable than a slightly larger room that shares a bathroom. You can apply percentage adjustments for specific perks.
Start with a 50/50 baseline, then add a few percentage points to the share of the room with each feature. The numbers below are the author's rule-of-thumb starting points for a conversation, not market data, so adjust them to your own apartment and local rents:
- En-suite Bathroom: Add 5-7 percentage points to that room's share. Not having to share a shower or clean up someone else's sink mess is worth a lot to many people.
- Walk-in Closet: Add 2-3 points. Extra storage space outside of the main bedroom floor plan has real value.
- Private Balcony/Patio: Add 2-3 points.
- Significant Windows/Natural Light: Add 1-2 points. If one room is dark and the other has floor-to-ceiling windows, the sunlight has value.
Using these adjustments, a roommate with the master bedroom, private bath, and a balcony in a $2,000 apartment might end up paying 60% of the rent ($1,200), leaving the roommate in the smaller room paying 40% ($800). This is a separate method from the square-footage example above, so the two splits differ; pick one method and stick with it.
The "Blind Auction" Method
If you would rather not measure rooms, you can let each roommate's own valuation set the price. The blind auction lets you price rooms without pulling out a tape measure.
You and your roommate both want the Master Bedroom. You each secretly write down the highest monthly rent you would be willing to pay for the Master Bedroom, assuming the total rent is $2,000. You reveal the numbers at the same time.
Roommate A writes: "$1,100"
Roommate B writes: "$1,250"
Roommate B values the Master Bedroom more, so B gets it. But B should not simply pay the $1,250 they wrote down, because that is the most B would pay, so B would gain nothing from winning. Any price for the Master Bedroom between the two bids works for both people: A is happy to stay in the smaller room if the Master costs at least $1,100, and B is happy to take the Master if it costs no more than $1,250. A simple way to pick is to split the difference: the Master Bedroom costs $1,175 and the smaller room costs $825.
Handling the Monthly Split
Once you agree on a custom rent split (e.g., $1,167 vs. $833), do not send separate weirdly-sized checks to the landlord every month. It's confusing and increases the risk of a bounced payment.
Instead, have one person pay the landlord the full $2,000 and the other roommate send their agreed share ($833 in this example) to that person each month. A shared spreadsheet or a bill-splitting app can keep track of it.