Rent split calculator

The four ways to split

• Equally: everyone pays the same. Simple, and fair when rooms are similar and incomes are close.
• By income: each person pays the same percentage of their income. Someone earning 6,000 pays 1.5 times as much as someone earning 4,000.
• By room size: a bigger room costs more. Part of the rent (the "shared space %") covers the kitchen, living room and hallway that everyone uses, and is split equally per person. The rest is split by bedroom size. Extras such as a private bathroom, balcony or walk-in closet add a percentage to that room's size (10% means the room counts as 10% bigger).
• Custom: type the percentage each room pays, for example after you have agreed it together. They must add up to 100%.

A couple sharing a room pays that room's share between them, equally or by their two incomes. Shared bills are usually split equally per person, because everyone uses the heating and the internet; you can split them the same way as the rent instead. Amounts are rounded to the cent, and any leftover cents go to the shares that were rounded down most, so the total always matches the rent exactly.

room share = shared % × people ÷ everyone  +  (100% − shared %) × size × (1 + extras %) ÷ total adjusted size

Worked example

Rent 2,400 a month plus 300 of bills, three bedrooms, four people (the example filled in above), split by room size with 20% for shared space:

• Shared space: 20% of 2,400 = 480, or 120 per person. Room A and Room C pay 120 each; Room B, with a couple, pays 240.
• The other 1,920 is split by adjusted size. Room A is 180 sq ft with a private bathroom (+10%), so it counts as 198. Room B is 140, Room C 110, a total of 448.
• Room A: 1,920 × 198 ÷ 448 = 848.57. Room B: 1,920 × 140 ÷ 448 = 600. Room C: 1,920 × 110 ÷ 448 = 471.43.
• Rent per room: A 968.57, B 840.00 (420.00 each for the couple), C 591.43. Total 2,400.00.
• Bills split equally 4 ways: 75 each. So the person in Room A pays 1,043.57, each person in Room B 495.00 and the person in Room C 666.43, which adds up to 2,700.00.

Which method is fairest?

There is no single right answer; it depends on what your household agrees. Room size works well when bedrooms differ a lot. Income works well for couples or friends with very different pay who want everyone to keep a similar share of their income. Many households mix them: room size for the rent and equal bills, which is the default here. Whatever you choose, agree it before signing the lease and write it down. Splitting a single meal or bar tab instead? Use the tip calculator and bill splitter.