# Rent Calculator – FAQ

Splitting rent with your friends shouldn’t be stressful. If your rooms are different sizes or different levels of niceness, Splitwise’s rent calculator will give you a neutral and objective opinion on how to share the rent. It’s great for close friends or Craigslist strangers, because it gives you the “market” value for how the rent should be fairly split, without having to actually haggle on anything.

Things it handles really well:

• Unequal room sizes
• Some rooms are being shared by a couple
• Up to 8 bedrooms
• Some rooms have no windows, huge closets, bad sound isolation, private bathrooms, etc.

### Method

The calculator uses a simple method used in real estate evaluation – price per square foot.

• The bedroom costs are shared by the people sleeping there
• The common areas of the apartment are shared equally per person.

This is a pretty simple method which I think is fair and makes sense.  This calculator makes it easy to do and easy to agree on!  If you want to include bills, we recommend you also split these equally per person.

### An example

Let’s say a couple (call them Jon and Rebecca) are sharing a \$1200/month 2-bedroom apartment with a single person (Kevin), and both bedrooms are of equal size. Let’s say that the size of the kitchen+living room+bathroom is roughly the same size as both bedrooms combined. Then it would be split as follows:

Cost of common areas: \$600, split 3 ways is \$200
Cost of bedrooms: \$300 per room
Jon pays: \$150 for 1/2 bedroom + \$200 = \$350
Rebecca pays: \$150 for 1/2 bedroom + \$200 = \$350
Kevin pays: \$300 for bedroom + \$200 = \$500

This is good for everyone!  Kevin saves \$100/month (\$1200 per year!) by living with a couple instead of a single roommate, while Rebecca and Jon save money over living alone – single apartments are usually more expensive per square foot. It’s fair, because everyone pays for what they get, and saves money for anything they share. If Jon and Rebecca’s room is larger, then the calculator can take this into account as well and their rent will be more similar to Kevin’s.

### And more

The calculator makes adjustments based on the quality of the rooms as well – private bathrooms, having no windows, not having a door – stuff that really matters.  The amount of the adjustments has been set by a questionnaire which what people would be willing to pay for various improvements. You can read those results here.

### But this is too complicated!

“Just splitting it” can be complicated with people’s feelings. People who got a less nice room sometimes feel quietly upset or resentful, but they don’t want to negotiate. This atmosphere makes it harder on everyone. Keep everyone paying a fair share without negotiation – that’s simple!

If you’re still worried the calculator is too weird, try it for yourself and see how you like it!  It only takes a few seconds and see the results for yourself – I think you’ll like it.

### 18 Responses to Rent Calculator – FAQ

1. Pingback: Splitwise Blog

Dear Spliwise,
Have you considered solving the room assignment-rent division problem (as some like to call it) with an auction? This could either be done iteratively or sealed-bid (there exist multiple algorithms for each). A simple implementation would be as follows:
1) Initialize all rooms to prices rent / number of rooms
2) Have each agent submit his/her most preferred room
3) Increase the price of rooms receiving bids and decrease rooms without bids (in proportion to number of bids received – much room for tuning here)
4) Repeat until each room is selected by exactly one agent
The only problem with this problem is that it might not always converge and that it may take many iterations if the increases / decreases are not set appropriately. This could pretty easily be implemented through your website sending out e-mails to participants all bids for a round has been submitted and a solution has been found or a new round must be executed.
Br,
Paul

3. Hi Paul,

Thanks for the fun suggestion. We have definitely thought about various auction mechanisms, since after all, an auction can (hypothetically) accurately price people’s specific preferences, instead of something like a general average, which is what you get from a survey-based approach.

I’ve spoken with some economists about this in the past, who made me realize that auctions are not as simple as they seem when there is a fixed total price for the house. As you noted, many simple auction mechanisms based on a fixed total price have incentive comparability and/or convergence problems. There is a very interesting paper here by Francis Edward Su (http://www.math.hmc.edu/~su/papers.dir/rent.pdf) that uses Sperner’s Lemma to do it properly. It uses relatively minimal assumptions to achieve a fair rental division, but involves a multi-step, multi-user interface that would take quite a lot of repeated interaction by users spread out over time. At least for now, we think that it is a bit too burdensome to be worth implementing.

Splitwise was created to deal with things in a practical way. While I am totally the sort of nerd who would enjoy auctioning the rent prices for rooms in an house, I feel that most people would think of ah auction as very unfriendly and would not accept it. Auctions make explicit the sense that things are adversarial. The goal with the rent calculator was to create something that emphasized simplicity, efficiency, and harmony so that people would want to use it. It’s not perfect, but it’s easy to get an answer and informs the conversation with community wisdom.

If you are interested in programming an auction tool, we might be interested in hosting it here – let me know!

4. Jester says:

Splitwise,

I am planning on having my girlfriend move in with myself and my friend/roommate in a 2 bedroom apartment priced at around 2000 a month. He is ok with the situation but we cannot agree on pricing. I explained this site to him and he seems to disagree with your calculations. He claims that as a couple we CHOOSE to live together in the same room and that it is not an inconvenience, so square footage does not matter. He believes that we should all pay exactly 1/3 of the cost regardless of whether he gets more usable room for his money. I know this is a question of philosophy but I would like to learn the ideology behind your system to possibly better explain it to him. Thanks!

• Jon Bittner says:

You can find a simple description of the philosophy here: http://blog.splitwise.com/rent-calculator-faq/. You should let your roommate know that this has been tested with surveys and reflects positive feedback from thousands of happy users! But of course, Splitwise is a starting point, and try and come to an agreement that makes sense to both of you. If you can’t agree at all about this, you should probably find a new roommate, as there are lots of people happy to live with couples and save some money.

5. Hi guys, we have exact square footage for the rooms, and it seems a bit weird to have rooms that have significant differences in size pay the same amount just because they round out to the same of the 5 values you offer, so I’d like to replicate the calculator myself.

The splitting by square footage is described here and easy enough, but I’m not sure how to value the other factors (closets, noise, etc) because the link to the survey results is down. Could you fix that or give us some indicator of how to price those?

Thanks!

• Jon Bittner says:

Hi @Robert,

Thanks for commenting. I’d be happy to work it out for you with exact measurements if you send me the specifics. We prefer to publish our calculator use the big buckets to help people round and not sweat the small stuff.

Cheers,
Jon

6. Mitzi says:

This is a nifty way to calculate for long-term leasing but I have a question about a weekly vacation rental. We have a house rented for 1 week. Eight people will be there all 7 nights, 4 people will be there 3 nights. How do I calculate so that everyone pays their fair share?

• Jon Bittner says:

Hi @Mitzi,

Great question! We have a calculator for sharing weekly vacation rentals too – check out the travel calculator. This uses a “per person-night” formula, and has a nifty way to visualize the input as well as share the results without signing up for anything.

Hope this helps,
Jon

• Mitzi says:

PERFECT! Exactly what I needed. Thank you!

• Mitzi says:

Hi Jon, I set up a “splitwise” account, but cannot figure out how to get anywhere past settling a tab. Can I get to the calculators from that website. I also don’t see a link to your blog from the home screen. Assistance please.

Mitzi

7. kiki says:

Hi! so if the other rooms do not check that they have a private bathroom, do you just assume the rest of the rooms are splitting one bathroom? how does that work exactly? we have one room with a private bath and the other 3 rooms share a bathroom.

Thank you,
Kiki

• Jon Bittner says:

Hi Kiki,

Basically yes – we assume that the others are sharing one or two bathrooms (we don’t make any valuation assumptions based on total bathrooms).

One bathroom for three people sounds pretty normal for me, so I’m not sure I’d recommend doing anything special in your case. The rent calculator should give you a fairly accurate answer. I’m sure there is a limiting case (like a hallway bathroom shared by 10 people vs one private bathroom) where this formula would not work, but I think 3 people sharing a bathroom is fine. Unless the bathroom is so busy that people very frequently have to wait to shower in the morning.

Intuitively, I see why having a private bathroom would be more desireable the more people who are sharing the shared bathroom. However, the calculator doesn’t take that explicitly into account – it uses a square-footage-based formula, in which a private bathroom is assumed to be a modifier to the bedroom and a public bathroom increases the overall size of the common space.

I hope this helps.

Cheers,
Jon

8. Jaime says:

Hi.
My roommates and I are trying to split the rent for our new apartment fairly. There are 3 bedrooms and 3 people. One bedroom has a balcony and private full bath with a window. The 2nd bedroom has a balcony and a 3/4 bathroom with a door to the public area as well. The 3rd bedroom has no balcony but a large full bathroom. Your calculator doesn’t have an option for anything but full or half bath and I don’t know if “awesome” windows are equal to a balcony. Any advice?
Thanks!
Jaime

Split wise,

My partner and I used the calculator. In doing so, we discovered we will not save any money by sharing a place with another roommate using your system. Its actually \$20 dollars more by having a roommate and using this system! We were truly hoping to share a place to save money. In this case, what do you do?

Also, I noticed there is no calculations for other living accommodations for roommates. Such as backyards, storage closets, and garages. If one roommate needs the garage or extra storage space and another doesn’t at the moment, how do you factor that in?
Even social situations can cause frustration. For instance, a couple and one individual is sharing a place, and they split rent by your calculator. Well the single roommates partner is constantly over/ staying the night. How does that play in?

I think this system is great probably for most, just not completely solid. Not only am I dealing with a few of these dilemma, but know quite a few people who are/ or have. I would love to hear your insight.

10. Jo says:

Split wise,

How can I know by square meters the size of a normal, generous or large room as it is not specified on the page. At the moment in my flat we have two bedrooms, one is 16m2 and the other 12m2 with tiny common areas, How would you categorise them.

Kind regards,
Jo