How to Split Rent With Roommates

Below you’ll find the best formulas and methods that you can use to calculate a fair rental split. 

How to Split Rent With Roommates Methods

1. How to Split Rent Evenly
2. How to Split Rent By Income
3. How to Split Rent By Square Footage
4. How to Split Rent Using Sperner’s Iemma

1. How to Split Rent Evenly

Splitting rent evenly can work well in cases where the rooms are of equal size or when the roommates value each room similarly, but that’s rarely the case. Individual rooms might be different sizes or have various amenities, such as a view, a more spacious closet, or even an en-suite bathroom. However, if you and your roommates think the rooms are more or less equal, this is the way to go as it’s incredibly straightforward. 

2. How to Split Rent By Income

Using your income to calculate the rental split is something that is typically reserved for couples, as it rarely makes sense for friends or roommates. If you’re going to be living with your partner, however, it can be quite fair to calculate a rental split based on your income. To do this, you’d use the following formula:

Each partner’s individual Gross Income divided by Total Gross Income (Partner A Gross Income + Partner B Gross Income). This would give you the percent of the rent which you should be responsible for. Here’s an example- If you make $40,000 and your partner makes $60,000, you’d divide $40,000 by $100,000, getting 0.40, which would mean you pay 40% of the rent. If your rent is $2,000/month, you will pay $800, while your partner would pay $1,200. 

3. How to Split Rent By Square Footage

Another way to split the rent is based on the square footage of the bedrooms. To do this, you’d first want to assign a value to the common areas, and then calculate the rent for each room based on its size. Let’s say you’re renting a two-bedroom apartment, and one room is 120 square feet while the other is 80. You’d start by assigning a value to the common space, let’s say $300, and then you’d use a calculator to figure out the rent split for each room. The formula would look like this: 

Room Rent (Total rent - Common Area Rent) / Combined Room Size = Price Per Square Foot; PPSQ x Room Size = Room Rent. 

In our example that would mean $700 / 200 sq feet = $3.50/ square foot. You would then multiply the PPSF by the individual room size to get the room rent. In our example, the 80 square foot room would have a rent of $280, while the 120 sq foot room would have a rent of $420.

You’d then split the common area rent between the roommates to calculate their monthly rent, which in this example would be $430 and $570, respectively. 

While splitting rent by square footage sounds fair, it isn’t always going to be the most reasonable solution as it doesn’t account for how useable the space in each room is or for other features the rooms may have. 

4. How to Split Rent Using Sperner’s Iemma

Another way to fairly split the rent is to use Sperner’s lemma. This essentially creates a method that takes into account each roommate’s personal preference and value for each room. While there are multiple complicated ways to calculate the value of each room, the simplest involves the roommates bidding for each room.

To make your life easier and save you time, the easiest option is to use this NY Times rent splitting calculator. The calculator is based on Sperner’s lemma. The algorithm behind this calculator is quite sophisticated, and the methodology is described in greater detail by the NY Times. The vast majority of roommates who use this calculator find the rental split suggested to be quite fair. 

How Do You Value the Shared Living Area?

Setting a value for the shared living space can be tricky, and there isn’t necessarily a formal way to calculate it. The best thing to do is to discuss it mutually and agree to a value that sounds fair to everyone. If you’re unsure and need some guidance, a good rule is to consider how big the living room is compared to the bedrooms. If, for example, the living space is similar in size to the bedrooms, and there are two bedrooms, a good place to start would be to assign a third of the monthly rent to the shared space. If you have three bedrooms and a similarly-sized common area, you can allocate 25% of the rent to it, and so on. Once you’ve calculated and set a value for the shared living space, it’s relatively straightforward to figure out the rent split for each roommate.  

How To Split Rent With a Couple

Splitting rent when one of the rooms in the apartment is occupied can be very tricky. It’s so complicated, in fact, that the typical rent splitting calculator won’t even offer this as an option. That being said, the best way to fairly split rent with a couple is by assigning a value to common areas in the apartment. This way, each room still has a value, and the couple won’t pay a premium for the room, but together they will pay double what other roommates would for the use of the common areas. For example, if you’re renting a $3,000 two-bedroom apartment with equal-sized bedrooms, and you assign a $1,000 to the shared living space and $1,000 rents to each bedroom, the rent split would be as follows:

You can use this method for all types of scenarios as the only trick is to fairly calculate the price of each room and the shared living space. This is also the fairest way to split shared utilities. Using the above example, let’s say the internet, electric, gas, and other shared utilities come to $300/month, the single roommate would pay $100 while the couple would pay $200. 

What Is the Best Rent Split Calculator?

There are numerous rent splitting calculators out there, but the best one is the rent split calculator from the New York Times as it uses Sperner’s lemma. While this method might not be the best when one room is occupied by a couple, it tends to work very well when each room, regardless of size or amenities, is occupied by a single roommate. 

Remember that when using any rent split calculator, one of the best ways to know you’ve come up with a fair result is that every roommate will be happy with their room and the price they pay. The goal is that nobody would prefer to trade their room and monthly rent obligation for another. If everyone’s satisfied, you have a fair rental split. 

Splitting Rent With Roommates Bottom Line

There are many ways to split rent with roommates, so you shouldn't have trouble finding a way of splitting rent that is fair to everyone. All you need to do is decide on a method you are all happy with and then calculate how much everyone owes. You can also use a rent split calculator to determine how much rent each roommate owes.