# How to split an electric bill with roommates

Canonical URL: https://www.evenoutapp.com/guides/how-to-split-electric-bill-with-roommates
Updated: 2026-10-06

Estimate each heavy device's kWh as watts times hours a day divided by 1,000, then multiply by the days it runs and by your bill's rate per kWh, and charge that to the device's owner. Split what is left equally. On a made-up $165 bill, a window AC adds $36 for its owner, who pays $68.25 while each other roommate pays $32.25.

Key points:
- Daily kWh = watts × hours a day ÷ 1,000. A 1,000 W window AC running 8 hours is 8 kWh a day, or 240 kWh over 30 days.
- At a made-up $0.15 per kWh, that AC costs $36.00. Take it off a $165.00 bill and split the remaining $129.00 four ways, which is $32.25 each.
- Carve out only devices above a cutoff the house agrees on, such as $10 a month. A $9.00 gaming PC stays in the shared pool.
- Average 12 months of bills for a flat monthly payment, then true up when the year ends or when someone leaves early.
- The Department of Energy puts plug-in energy monitors at around $25 to $50. A monitor settles arguments over hours, but it only reads devices on a 120-volt outlet.

## How do you split an electric bill when one room uses much more?

Charge the heavy device to its owner, then split what is left equally. This works for something that clearly uses more than anything else in the home: a window air conditioner, a space heater, a gaming PC that runs all day or a car charger. The steps below use a hypothetical June bill for four roommates, Noor, Owen, Priya and Tomas, where Noor runs a window AC in her room.

1. **Find your rate.** Divide the bill by the kilowatt-hours (kWh) it lists. A $165.00 bill for 1,100 kWh is $0.15 per kWh. That rate is made up for this example, so use the one on your own bill. If your bill has a fixed monthly charge, [how to split electric and gas bills fairly](https://www.evenoutapp.com/guides/split-electric-and-gas-bills) shows how to take it out first.
2. **Estimate the device's daily kWh.** The U.S. Department of Energy gives this formula: (watts × hours used per day) ÷ 1,000 = kWh per day. Noor's AC is 1,000 watts and runs 8 hours a day, so 1,000 × 8 ÷ 1,000 is 8 kWh a day.
3. **Multiply by the days it runs and by the rate.** 8 kWh × 30 days is 240 kWh, and 240 kWh × $0.15 is $36.00.
4. **Take that off the top.** $165.00 minus $36.00 leaves $129.00.
5. **Split the rest equally.** $129.00 ÷ 4 is $32.25 each.

Noor pays her $36.00 plus her equal share, $68.25. Owen, Priya and Tomas pay $32.25 each. The four amounts add back to $165.00. An equal split would have been $41.25 each, so Noor pays $27.00 more and each of the others pays $9.00 less.

## What can heavy devices cost a month?

A window air conditioner and a space heater cost $36.00 and $40.50 a month at this rate, while a gaming PC or a work desk stays under $10. The table runs the same formula on five example devices, with wattages and hours picked for illustration, all at the made-up rate of $0.15 per kWh.

| Device | Estimate | Month total | Cost |
|---|---|---|---|
| Window air conditioner | 1,000 W × 8 h ÷ 1,000 = 8 kWh a day | 240 kWh (30 days) | $36.00 |
| Space heater | 1,500 W × 6 h ÷ 1,000 = 9 kWh a day | 270 kWh (30 days) | $40.50 |
| Gaming PC | 400 W × 5 h ÷ 1,000 = 2 kWh a day | 60 kWh (30 days) | $9.00 |
| Work desk (laptop, monitor, lamp) | 250 W × 8 h ÷ 1,000 = 2 kWh a day | 40 kWh (20 workdays) | $6.00 |
| Car charger | 7,200 W × 1.5 h ÷ 1,000 = 10.8 kWh a day | 216 kWh (20 days) | $32.40 |

The charger's 7,200 watts comes from a hypothetical label of 30 amperes at 240 volts. Yours will differ, so read your own labels.

Agree on a cutoff before the first bill. Say the house decides that anything under $10 a month stays in the shared pool. The gaming PC at $9.00 and the work desk at $6.00 stay shared, and the AC, the heater and the charger are carved out. Without a cutoff, every device becomes an argument. A heater owner pays in winter and an AC owner in summer, so the carve-out changes with the season. Work it out fresh from each statement.

## What if the bill swings with the seasons?

Average the last 12 bills for a flat monthly payment, then true up. Say the year's bills run January $142, February $138, March $104, April $86, May $92, June $165, July $188, August $181, September $122, October $90, November $96 and December $132. The year totals $1,536, so the average is $1,536 ÷ 12 = $128.00 a month, and each of four roommates pays $32.00. If a device is carved out, bill it to its owner each month as in the first example, and average only what is left.

The account holder pays the real bills and the roommates pay the flat $32.00. In months above $128.00, such as July at $188, the account holder fronts the difference, and the months below it pay that back. At the end of the year, add up the real bills and compare. Say the next year's bills total $1,560 while the roommates paid $1,536. The $24.00 gap is $6.00 each.

The flat payment only fits people who stay all year. Say the bills run as listed above, the flat $32.00 is already set, and Tomas leaves after the August bill. The first eight bills total $1,096, so his quarter is $274.00. He paid 8 × $32.00 = $256.00, which leaves him $18.00 short. Settle that before he goes, and the three who stay start a new average.

## When is a plug-in energy meter worth buying?

When a device is above your cutoff and the owner disagrees about the hours. The Department of Energy's guide puts electricity usage monitors at around $25 to $50 at most hardware stores and says they measure any device that runs on 120 volts. Plug the monitor into the outlet and the device into the monitor, then read the kWh later. They suit devices that do not run constantly, and some let you enter your rate.

The numbers decide it. Over a four-month summer a $36.00 AC adds up to $144. Say a $40 monitor settles the hours in one billing period. That is a small cost, and four people can split its price at $10.00 each. A $6.00 desk is not worth the trouble. The monitor does not suit the large appliances the Department of Energy lists as unsuitable, such as a clothes dryer or a central air conditioner. For a 240-volt device such as the charger, use the label estimate.

## How do you record it in EvenOut?

Make a Household group, which is the type labelled "Rent and bills", and add the bill as an expense in the Utilities category. Choose "Exact amounts" in the split picker and type $68.25 for Noor and $32.25 each for the other three. The pill reads "All assigned" once the amounts match the $165.00 total. EvenOut does not work out the kWh for you. It splits the amounts you give it.

For the flat plan, add the $128.00 as an expense paid by the account holder, split equally, and set Repeat to Monthly under "Photo, repeat, pending or note". EvenOut adds each later month as a normal expense with the same payer and split. A repeat has no end date, so open "Repeating expenses" from the group menu and choose "Stop repeating" at the year's end. Then add one more expense for the true-up. Setting up a repeat needs a connection.

## What should you do next?

Write down the cutoff, the rate you use and the month you true up. [How to split utilities between roommates](https://www.evenoutapp.com/guides/how-to-split-utilities-between-roommates) covers the other bills, and [what expenses roommates should split](https://www.evenoutapp.com/guides/what-expenses-should-roommates-split) covers everything else in the house. The [split utilities calculator](https://www.evenoutapp.com/tools/utilities-split-by-usage-calculator) does the sums when a bill has a fixed charge and you know each person's usage. If a roommate falls behind on their share, [what to do about a roommate not paying bills](https://www.evenoutapp.com/guides/roommate-not-paying-bills) has the steps.

## Frequently asked questions

### Where do I find a device's wattage?

The Department of Energy says the wattage is usually stamped on the bottom, the back or the nameplate. If only amperes are listed, multiply amperes by volts. Its example is 120 volts times 3 amperes, which is 360 watts. Most US appliances use 120 volts.

### Is the estimate accurate enough to bill someone?

Treat it as a ceiling, not a measurement. The wattage on the label is the most the device draws, and many have settings that draw less, such as a fan on low. Count the hours it actually runs. If the figure is over your cutoff and the owner doubts it, measure it with a plug-in monitor for one billing period, which works for devices on a 120-volt outlet.

### What if two roommates both run window ACs?

Carve out both. On the $165.00 bill, two $36.00 ACs take out $72.00 and leave $93.00, which is $23.25 each across four people. Each AC owner then pays $36.00 + $23.25 = $59.25, and the other two pay $23.25.

## Sources

- [U.S. Department of Energy: Estimating Appliance and Home Electronic Energy Use (archived January 2026)](https://web.archive.org/web/20260101020334/https://www.energy.gov/energysaver/estimating-appliance-and-home-electronic-energy-use)