ROOMMATE RENT SPLITTER · RUNS IN YOUR BROWSER · NOTHING UPLOADED

Split rent fairly when the rooms are not equal

Everyone says what each room is worth to them. The tool gives the rooms to the people who want them most and sets the rent for each so the total is exactly right and nobody would rather have someone else's room. No more arguing about the master bedroom, and no more splitting by square feet when one small room has the private bath.

How it works, with a worked example: how to split rent with unequal rooms.

1. The household

2. What each room is worth to each person

Each row is one person. Spread any amount across the rooms: only the proportions matter, and each person's numbers are scaled to the total rent. Putting more on one room means putting less on the others. Fill in your row privately before comparing.

Fill in the grid, then click Split the rent.

How it is built

Rooms: the tool tries every way of giving each person one room and keeps the one with the highest total stated value.

Prices: it then finds prices that add up to the rent where no person prefers another room at its price, and among those it makes the least-happy person as happy as possible. This is the envy-free rent division of Su (1999) and Gal et al. (2017), solved with shortest paths and a bisection.

Checked: the test suite runs hundreds of random households of two to eight people and confirms that the rent always adds up exactly, every room is held by one person and nobody envies anyone, and compares the room assignment with a brute-force search.

Common questions

How do you split rent fairly when the rooms are different sizes?

Do not split by square feet alone, because a small room with a private bathroom can be worth more than a big one with none. Give each roommate the same amount of money to spread across the rooms to say what each room is worth to them. The tool gives the rooms to the people who value them most in total and sets prices so that nobody would rather have someone else's room at that room's price.

What does envy-free mean?

At the prices shown, every person is at least as happy with the room and price they got as with any other room at its price. Nobody can say they would be better off swapping, so there is nothing to argue about afterwards.

Do I have to be honest with my values?

Yes, and it works best when everyone enters them privately before comparing. Each person spreads the same total rent across the rooms, so putting more on one room means putting less on the others. Inflating a favourite room raises its price and can cost you the room, so honest values are the safest strategy.

Why does one person pay less than an equal split?

Equal splits ignore that rooms differ. A person who values the smallest room at less than an equal share pays less for it, and the people with the better rooms pay more. All three are better off than under an equal split because the extra value of each room goes to whoever values it most.

What if two people want the same room?

The tool compares every possible way of giving out the rooms and picks the one with the highest total value, then raises the price of the contested room until the person who values it less is happier elsewhere. A tie is broken by the order of the names, so the outcome is the same every time you run it.

Is my information uploaded?

No. Everything is calculated in your browser, there are no accounts, and nothing is sent to a server. Use Save to download a file if you want to reopen the split later.

Is this legal or tenancy advice?

No. It is arithmetic on the numbers you type. Your lease, local law and landlord decide what you owe the landlord; this only helps roommates divide it between themselves.