🏠 Roommate Utility Bill Split Calculator

Add each roommate and their share weight (equal by default, or adjust for room size / occupancy) to split a utility bill proportionally.

Total bill ($)

Weights are ratios, not amounts

Each person's share is their weight over the sum of all the weights:

share  = weight / sum of all weights
amount = share × total bill

The rows on load are Alice 1, Bob 1 and Cara 2, so the weights total 4 and a $400 bill splits $100, $100, $200. Only the proportions matter: 2, 2, 4 and 0.5, 0.5, 1 produce exactly the same three amounts, so you never have to make the weights add up to anything in particular.

That is what makes the box flexible. Type square footage straight in and the bill splits by room size: 120, 100 and 180 square feet on a $400 bill gives $120, $100 and $180. Leave everyone on 1 for an even split.

Choosing a weighting the house will accept

By head for internet and streaming, where usage has nothing to do with which room you sleep in.
By room size for heating and cooling, which is the bill people argue about most.
By occupancy when a couple shares one room: weight 2 charges them per person, and 1.5 is the usual compromise against a single occupant.
By time in the house - someone away half the month at 0.5.

Settle the weighting when everyone moves in, not when the first $600 winter bill lands. A rule agreed in advance survives the month the heating runs constantly; one invented afterwards rarely does.

Frequently asked questions

How do you split utilities when the rooms are different sizes?

Put each room's square footage in as its weight and the tool does the rest. A 180 square foot master against two 110 foot rooms carries 45% of the bill, which is usually easier to agree than an argument about thermostats.

Should a couple sharing one room pay two shares?

They use water and power like two people but occupy one room, so a weight of 2 charges them per head and 1.5 splits the difference. Households commonly land on 1.5 for space-driven bills and 2 for per-person ones.

Why do the shares not add up to the bill exactly?

Each amount is rounded to the cent independently. Three equal shares of $400 come out at $133.33 apiece, a penny short of the total, so one person rounds up or the odd cent rolls to next month.