Thanks to interest from readers and responders like you, I have had a lot more opportunity to check my original work and the calculator is holding up quite well under public scrutiny. Thanks to everyone who gave feedback or wrote notes of congratulations – it’s made this whole project really, really fun!
Right after launch, I started collecting voluntary feedback from people using the calculator. Originally, I simply asked people to rate the calculator on a 1-5 scale. Here are the results from the first 1,338 respondents (before I switched the feedback system to the present one, which is still collecting data).
Just over 60% of feedback-givers who used the calculator rated the result as “fair” or “very fair,” and 84% gave it at least a 3 out of 5. The average score was a 3.63 out of 5. This does not take into account the response bias. People who thought the calculator was unfair seemed, if anything, more likely to give feedback: the average among people who wrote written comments had a lower average fairness of 3.48. (For reference, the total response rate was not recorded exactly but it is a few percent of the total). So I suspect that a very healthy majority of respondents think the calculator is doing its job.
The most common hand-written feedback was complimentary, but many more comments made suggestions either recommends extra features, alternate philosophies, or situations people think are currently unfair. Rebecca and I coded responses by category:
Some respondents were coded in multiple categories, so these do not sum up to 100%.
The top features that are requested are parking spots, balconies, who actually uses the common living spaces, more levels of closet niceness, bathroom specifications, an option to specify square footage, and to account for who is in charge or paying the bills. If you hate being the one to take care of the bills and figure out what people owe, try out our Bill Splitting App which is currently in Alpha development!
For several of the lesser suggested features, I think the best answer is to NOT take them into account. It’s not that these aspects of the room don’t matter at all – it’s just that quibbling over whether or not to check the box creates tension, and the whole point of the calculator is to remove tension. I only included boxes that I think are widely understood to be important – more space, more light, more privacy. The fewer boxes, the better, for everyone’s sake.
For instance, who furnishes an apartment is certainly fiscally relevant if people live together for over 3 years, but most people are able to roughly split this without discussion, and so long as everyone keeps what they bought, it should not factor significantly into the communal costs. In time, I will try and add some additional features for the items that I think are unambiguously useful (such as balconies or parking), but I want to keep it simple overall.
There are other things that are probably worth factoring in but are unique circumstances, hard to describe, or vary in importance depending on the location. For instance: smells, the size or excellence of a view, being in a basement of varying dankness, how people share common space, or how much of a common area is taken up by someone’s desk. For these, I suggest you use your intuition and use SplitTheRent.org as a starting point. For parking, look around for what people are charging on Craigslist and split it up between people who drive the car. If you and your girlfriend take up more of the common spaces, increase your bedroom size in the SplitTheRent calculator to account for common area you dominate. If you have enough bathrooms that some shared bathrooms are essentially private, don’t click on the private bathroom feature at all.
As one respondent says:
“One factor in this household is that the third bedroom has access to a large private roof terrace. Otherwise it seems like a very fair system. I guess that’s where ‘intuition’ comes in.”
The Splitwise Blog 
I don’t agree that furnishings should not factor into the communal costs. If you buy most of the furniture, you’re investing your own money into communal assets that are constantly deprecating, instead of being able to save for something for yourself such as a car or house, or being able to invest them in stocks etc. After you move out, you’re left with assets worth far less than when you bought them, and your housemates are left with all of the cash they didn’t spend on furniture.
I live with two other people and I own the fridge, TV, couch, dining set, barbeque, and washing machine. For that, I think I deserve the largest room, but going by your calculator I should be paying much much more than the other people in the house. It’s probably much fairer in other situations.
@rentyrent It definitely is worth something that you bought all the furniture for the apartment! Check out our furniture calculator if you want to figure out how much your roommates owe you for the “depreciation” (the decreased value of the fridge etc over time) on the things you bought. It may, or may not, add up to the differential in the room sizes, or be roughly the same, I have no idea.
Hands down, Apple’s app store wins by a mile. It’s a huge selection of all sorts of apps vs a rather sad selection of a handful for Zune. Microsoft has plans, especially in the realm of games, but I’m not sure I’d want to bet on the future if this aspect is important to you. The iPod is a much better choice in that case
I don’t think Splitwise is fair. The room sizes are too vague; you don’t just jump from normal to generous. There needs to be raw square footage taken into account. Splitting a room with someone should have no impact on the the way rent is divided. There is a general consensus that splitting a room sucks, regardless of who you’re splitting it with (be it a strange or significant other) . Less privacy, less space, and one closet to share is awful and warrents paying half rent since you get half a room. Fair and square. Rent is solely divided among rooms, based on size. What’s in the room does not matter. Utilities, however, are divided among the number of occupants equally. I wrote a rent calculator in C that takes into account the number of rooms and square footage, nothing more, nothing less.
Furniture definitely factors into cost. It costs lots of money to buy and/or rent furniture, especially nice furniture. If someone is furnishing the whole house and the others would have otherwise left it empty yet feel entitled, that demands lower rent. Allowing others to take advantage of my costly furniture on a daily basis isn’t for charity.