How to split rent fairly

Three fair ways to split rent

By bedroom size. Part of the rent pays for space everyone shares, like the kitchen and living room, and that part is split evenly. The rest is split by bedroom square footage, so the biggest room pays the most. Between 30 and 50 percent shared is a common starting point; pick the number together.

By income. Everyone pays the same percentage of what they earn. It suits couples and close friends better than roommates who just met.

Evenly. Simple, and fair when the rooms are close in size.

Agree on these before you sign

• A private bathroom, a balcony or a parking spot usually adds to that person's share.

• Utilities and internet are easier to split on their own, evenly or by use.

• Write down the split, the due date and who pays the landlord.

Keep track after move-in

Rent is the easy part. The small things are where roommates lose track: a utility bill one person paid, a grocery run, the deposit. Duesy keeps a private record of who owes whom on your phone, with no accounts.

A worked example by room size

Rent is $2,400 for three bedrooms of 150, 120 and 90 square feet, and the roommates agree that 40 percent pays for shared space.

• Shared part: 40 percent of $2,400 is $960, or $320 each.

• Private part: the other $1,440 is split by area. 150 of 360 square feet is $600, 120 is $480, 90 is $360.

• Totals: $920 for the big room, $800 for the middle room, $680 for the small one. Together that is $2,400.

A worked example by income

The same $2,400 split among incomes of $60,000, $45,000 and $30,000 a year, $135,000 in all. Each person pays their share of the total income: about $1,067, $800 and $533 a month.

A check on affordability

A common rule of thumb is that housing, including utilities, should take no more than 30 percent of monthly income. If one roommate's share pushes them past that line, an income split or a smaller room can keep the arrangement from falling apart in month four.

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