How the split works
Each bill is split on its own, using only the people who lived in the home during that bill’s period. The calculator gives each person points for the bill, then divides the bill by those points.
- Days present = the days a person lived there during the bill period, counting both the first and last day. A blank move-in or move-out date means they were there the whole time.
- Points = days present × weight. A weight of 1 is normal use, 1.5 or 2 is heavier use, and 0 leaves someone off that bill.
- Share = bill amount × that person’s points ÷ everyone’s points.
- Settle-up = what each person paid minus what they owe. The person who owes the most pays the person who is owed the most, and so on, until everyone is at zero. This takes at most one fewer payment than there are people.
Worked example
Alex, Sam and Jordan share an apartment. Jordan moved in on September 16, so Jordan was there 15 of September’s 30 days. Alex works from home and runs the AC, so the group agreed Alex carries a 1.5 weight on electricity. Alex paid the electric ($186.40) and internet ($65.00) bills; Sam paid gas ($42.10).
| Bill | Alex | Sam | Jordan |
|---|---|---|---|
| Electric $186.40 (points 45 / 30 / 15) | $93.20 | $62.13 | $31.07 |
| Gas $42.10 (points 30 / 30 / 15) | $16.84 | $16.84 | $8.42 |
| Internet $65.00 (points 30 / 30 / 15) | $26.00 | $26.00 | $13.00 |
| Total owed | $136.04 | $104.97 | $52.49 |
| Already paid | $251.40 | $42.10 | $0.00 |
| Balance | +$115.36 | −$62.87 | −$52.49 |
To settle up, Sam sends Alex $62.87 and Jordan sends Alex $52.49. Two payments clear $293.50 of bills, and nobody has to send money for each bill separately.
Choosing a fair method
No law tells roommates how to divide utilities, so the fair method is the one everyone agrees to before the bills arrive. Most households have one electric and one gas meter, which means nobody can measure each person’s use exactly. Common choices:
- Even split by days. Simple and hard to argue with. Good for internet, trash and other flat charges.
- Weighted split. Useful for electricity when one person has a space heater, a window AC or a home office. Keep weights modest; 1.5 already means 50% more than everyone else.
- Room-based split. Some groups split utilities in the same proportion as rent. Use the roommate rent split calculator for that.
If you want a rough sense of what an appliance adds to the electric bill, the appliance energy cost calculator estimates it from wattage and hours. The U.S. Energy Information Administration publishes average electricity prices by state each month if you need a benchmark.
Edge cases
- Bills that cross months. Enter the exact service period printed on the bill, not the month it arrived. Move dates are compared with that period.
- Someone moved out. Enter their move-out date. They pay only for the days they were there, including the last day.
- Deposits and late fees. A utility deposit or late fee belongs to whoever caused it or whoever holds the account; agree on that separately rather than mixing it into usage.
Next steps
Moving into a new place? See setting up utilities in a new apartment. If a roommate is moving in or out mid-month, the prorated rent calculator handles the rent side the same way.