RoomProrateHow to prorate a utility bill for a roommate who moved out
Updated 2026-11-01
Written for the searches "how to prorate utilities" and "prorated utilities meaning" (Google autocomplete, 1 November 2026). The amounts are a fictional bill run through the RoomProrate calculator on 1 November 2026.
Prorating a bill means sharing it in proportion to time. The tricky part is that utility bills rarely run from the 1st to the last day of a month, while leases and move-out dates usually do.
Step by step
- Use the billing period on the bill, not the calendar month. Here it is 18 March to 16 April: 30 days. See reading the billing period.
- Count each person's days inside that period, both ends included. Jo's last day is 31 March, so Jo was there from 18 to 31 March: 14 days, not 13.
- Use this period's charges, not the account balance.
- Choose how shared days are split: the daily split or person-days.
Worked example: a bill that crosses the move-out date
Kai and Jo share a flat. The electricity bill covers 18 March to 16 April (30 days) with 96.00 of usage and no separate fixed charge. Jo moves out at the end of March; Kai stays.
| Person | Days | Daily split | Person-days |
|---|---|---|---|
| Kai | 30 | 73.60 | 65.45 |
| Jo | 14 | 22.40 | 30.55 |
Daily split: 96.00 over 30 days is 3.20 a day. For the 14 days both lived there, each pays 1.60 a day, so Jo pays 14 × 1.60 = 22.40. Kai pays the same 22.40 plus all 16 days after Jo left (51.20): 73.60.
Person-days: 30 + 14 = 44 person-days. Jo pays 14/44 of 96.00, which is 30.55, and Kai 65.45.
Two mistakes that change the answer
- Counting one end only. If Jo's last day is entered as 30 March, Jo has 13 days and the daily split gives Jo 20.80 and Kai 75.20. Decide whether the move-out day counts, and enter that date as the last day.
- Splitting by the calendar month. Half of "March" is not half of this bill. Only the days inside the billing period count.
If the bill also has a standing or service charge, see sharing the standing charge when someone moves out.
Questions
What does prorated mean on a utility bill?
Prorated means divided in proportion to time. For roommates it usually means each person pays for the days they lived there during the billing period, rather than an equal share of the whole bill.
How do I prorate utilities for a roommate who moved out?
Take the billing period printed on the bill, count the days the roommate lived there in that period with both ends included, and choose how shared days are split. In the example on this page, a roommate who left on 31 March pays 22.40 of a 96.00 bill with the daily split, or 30.55 with person-days.
See all guides.