Roommate rent split calculator

What this split gives you

A shared lease has one rent and several people, and the argument is rarely about arithmetic. It is about whether the biggest bedroom with its own bathroom should cost the same as the small one next to the kitchen. The calculator turns an agreed rule into dollars: it turns room sizes, a bathroom premium or incomes into weights, divides the rent by weight, and splits utilities by people. Use it to put a proposal on the table, then change one number at a time and see who gains.

Worked example

Rent is $3,000 for three rooms of 200, 120 and 150 square feet; the 200-square-foot room has its own bathroom, and utilities are $200. Weights by size alone are 200, 120 and 150, a total of 470, so the shares are $1,276.59, $765.96 and $957.45. With a 10% bathroom premium the weights become 220, 120 and 150, a total of 490, and the shares are $1,346.94, $734.69 and $918.37. Add $66.67 of utilities each (three people, one per room) and the totals are $1,413.61, $801.36 and $985.03.

How do I split rent fairly between roommates?

There is no single fair answer, only rules people agree on. Start from the total rent and choose what the split should follow: equal shares, the size of each room, or each person's income. Take the example in the form: $3,000 rent for three rooms of 200, 120 and 150 square feet, and $200 of utilities. Equal shares give everyone $1,000.00 of rent. Splitting by room size gives $1,276.59, $765.96 and $957.45. Giving the 200-square-foot room 10% extra weight for its private bathroom moves the first share to $1,346.94 and lowers the others to $734.69 and $918.37. Splitting by income ($5,200, $3,400 and $4,100 a month) gives $1,228.35, $803.15 and $968.50. These are example numbers, not market prices.

How is each share calculated?

Every room gets a weight, and each person pays rent × own weight ÷ total of all weights. For equal shares the weight is 1. For room size the weight is the square footage, multiplied by 1 + p ÷ 100 if the room has a private bathroom and you set a bathroom premium of p percent. For income the weight is the monthly income. The result is rounded to the cent with the largest-remainder method, so the shares add up to the rent exactly, with no stray penny. Utilities follow a different weight: the number of people living in each room, because a couple in one room uses roughly twice the water and power of one person.

Should a couple in one room pay more?

Usually they pay more for utilities and sometimes for rent, but that is a house agreement, not arithmetic. In this calculator you enter 2 in the people field for the couple's room. Utilities of $200 are then split four ways, so the couple pays $100.00 of them and each single roommate $50.00. Rent is still set by room size, bathroom and income; if you want the couple to carry two shares of rent, list them as two rooms or raise the room's size or income value.

Is splitting by income fair?

It spreads the burden by ability to pay: each person pays the same share of the rent as their share of the household income. In the example the largest income pays $1,228.35 (40.9% of the rent) and the smallest $803.15 (26.8%). The catch is that the person with the smallest room can end up paying the most, or the best room can go to the lowest earner, and everyone has to be willing to share pay information. It works best when the rooms are similar. If you would rather not disclose incomes, agree on percentages first and enter them in the income fields instead.

What is an envy-free rent split, and does this calculator do it?

An envy-free division is one where no roommate would prefer to swap rooms and prices with anyone else. Computing one needs every person to state how much each room is worth to them. The free tool Spliddit asks exactly that, then matches people to rooms to maximize the total value and sets prices that maximize the smallest benefit while staying envy-free (Gal, Mash, Procaccia and Zick published the method as "Which Is the Fairest (Rent Division) of Them All?"). This calculator does not do that: it applies simple rules to sizes, bathrooms and incomes. If the rooms are very different, or two people want the same room, try the bidding approach.

How should we split utilities and internet?

Common choices are equal shares, or per person for water and power, and equal shares for internet and streaming. The calculator splits the utilities total by the number of people in each room. Enter 0 for utilities if each person pays their own bills. Agree on the rule before the first bill arrives, and decide who is named on the accounts.

Common mistakes

Measuring only the bedroom and forgetting the closet, or the shared living room that one person uses as a bedroom, skews the weights; agree on how you measure first. Setting the premium by feel produces arguments; trying 5%, 10% and 15% in the form shows how little the number moves each share. Mixing rules without saying so is the other trap: income-based rent with size-based utilities is fine, but write it down. Finally, a split among roommates is a private agreement. The landlord usually sees one lease, so check what your lease says about each tenant's responsibility for the whole rent before you rely on shares.

Limits of this method

Simple rules treat every person the same way and know nothing about taste. One roommate may gladly pay more for a quiet room, another may not care about the bathroom at all. A split can look fair on paper and still leave someone wanting to swap, which is what envy-free division is designed to rule out, at the price of asking everyone to put a dollar value on every room. For two people in two similar rooms, equal shares are almost always enough. For three or more different rooms, compare the size split here with a bidding tool such as Spliddit.

A planning aid for a private agreement among roommates — not legal or financial advice; your lease and local law decide what each tenant owes. Sources, checked October 27, 2026: Spliddit, Divide Rent (method description); Y. Gal, M. Mash, A. D. Procaccia and Y. Zick, Which Is the Fairest (Rent Division) of Them All? (ACM EC 2016; Journal of the ACM, 2017). Related: the rent affordability calculator, budget calculator, prorated rent calculator and emergency fund calculator. How we check our calculators.