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How to split the electricity bill with roommates

Split the electricity bill equally when everyone uses about the same power, and split it as "base plus extra" when one roommate runs something heavy like an AC: the shared base is divided equally and the heavy user pays for their extra units. The fairest version charges those extra units at the rate they actually added to the bill, which is often higher than the average rate.

Updated November 2026

The short answer: pick one of four methods

A sub-meter on one room or circuit makes the last two exact instead of estimated. Whatever you choose, agree it before the first bill arrives, not after.

Worked example: three flatmates, one AC

Aisha, Rohan and Kabir share a flat with one electricity meter. Kabir has an AC in his room and runs it most nights. This month's bill:

• Units used: 400
• Energy charge: the first 200 units at ₹4 each, units above 200 at ₹7 each, so ₹800 + ₹1,400 = ₹2,200
• Fixed and other charges: ₹180
• Total: ₹2,380

These tariff rates are an example to show the method. Your own bill lists the real rates for your area; use those.

Step 1: estimate the AC's units

One unit on an electricity bill is one kilowatt-hour (kWh): 1,000 watts running for one hour. So an appliance's units are its power in kilowatts × hours used. Kabir's AC draws about 1.6 kW (example figure; check the label or manual for yours, and note that inverter ACs draw less once the room is cool). He runs it about 5 hours a night on 20 nights:

1.6 kW × 5 hours × 20 nights = 160 units

That is 40% of the flat's 400 units. If the AC is on a plug-in energy meter or a sub-meter, use that reading instead of an estimate.

Option 1: split it equally

₹2,380 ÷ 3 = ₹793.33 each (one person pays ₹793.34 so the total comes to ₹2,380). Simple, but Aisha and Rohan are each paying about ₹373 a month towards Kabir's AC.

Option 2: base plus AC at the average rate

The average energy rate on this bill is ₹2,200 ÷ 400 units = ₹5.50 per unit. Kabir's AC costs 160 × ₹5.50 = ₹880. The rest, ₹2,380 − ₹880 = ₹1,500, is split equally: ₹500 each.

Option 3: base plus AC at the top rate (fairest with slabs)

Here is what the other guides miss. Without the AC, the flat would have used 240 units. The AC's 160 units are the ones that pushed usage from 240 to 400, and every one of them was billed at the ₹7 rate, not the ₹4 rate. Charging them at the average ₹5.50 quietly gives Kabir part of the cheap first slab, which Aisha and Rohan would have filled on their own.

So charge the AC units at the top rate: 160 × ₹7 = ₹1,120. The rest, ₹2,380 − ₹1,120 = ₹1,260, is split equally: ₹420 each.

There is a neat check that this is right. Work out the bill as if the AC had never been on: 240 units = 200 × ₹4 + 40 × ₹7 = ₹1,080, plus ₹180 fixed = ₹1,260. That is exactly the base the three of them now share. Everyone pays what they would have paid without the AC, and Kabir pays exactly what his AC added.

If your bill has one flat rate per unit, Options 2 and 3 give the same answer, so use Option 2.

Comparing the three

Step by step: base plus extra

1. Read the bill. Note the total units, the rate (or rates, if it has slabs), and the fixed charges.
2. Estimate the heavy user's units. Power in kW × hours a day × days used. Use a plug-in meter or sub-meter reading if you have one.
3. Price those units. One rate on the bill: use it. Slabs: use the rate of the highest slab the bill reached (if the extra units straddle two slabs, price each part at its own rate).
4. Split the rest equally. Total bill minus the extra cost, divided by the number of people. Fixed charges sit in this shared part.
5. Add the extra to the heavy user's share and check the total. The shares must add up to the bill exactly.

When someone moves in or out mid-month

Split the shared base by days lived in the flat, not by head. Say Rohan moved in on day 11 of a 30-day billing cycle, so he was there 20 days. Aisha and Kabir were there all 30. That is 30 + 30 + 20 = 80 person-days. The shared base of ₹1,260 works out to ₹1,260 ÷ 80 = ₹15.75 per person-day.

The same person-day method works for a flatmate who goes home for two weeks, if your group agrees that absences count. Many groups only count absences of a week or more, to keep it simple.

Someone works from home but has no AC

When the extra use is spread across lights, fans, a laptop and the kettle, estimating units is not worth it. A flat top-up is easier. Flatmates.com.au suggests the at-home person adds 25% to their equal share: on a 600 bill split three ways, they pay 250 and the other two pay 175 each. Pick a percentage your group agrees with and review it if routines change.

Who paid, and who owes what

Aisha paid the ₹2,380 bill from her account. Using Option 3:

A plus balance means the group owes you. A minus balance means you owe the group. The balances add up to zero.

1. Kabir pays Aisha ₹1,540
2. Rohan pays Aisha ₹420

In practice the electricity bill is one of several shared costs. Rent, Wi-Fi, gas and groceries all create balances too, and it is easier to settle everything once a month than bill by bill. Our guide to tracking shared expenses with roommates shows how.

Tips that prevent arguments

• Agree the method before the first bill. Summer is a bad time to start negotiating about the AC.
• Write down the AC estimate once. Wattage, typical hours, nights per month. Reuse it until habits change, rather than re-arguing it monthly.
• Re-check in the hot months and cold months. AC and heater use swing with the season, so an estimate from March will be wrong in May.
• Keep the bill photo with the expense. Anyone can then check the units and rates for themselves.
• Settle on a fixed date. The 5th of each month, for example, so nobody carries a growing balance.

How SplitSimple handles the electricity bill

In SplitSimple, create a group for the flat and add the electricity bill with an exact split, entering each person's amount from the method you chose. Bills that stay the same each month, like Wi-Fi, can be set up as a recurring monthly expense. Balances update as you go, Settle up suggests the fewest payments, and in rupee groups a UPI link opens the payer's UPI app with the amount filled in. SplitSimple never holds or moves the money itself.

FAQ

Related

• How to split rent fairly
• How to track shared expenses with roommates
• Rent split calculator
• Flatmate expense tracker
• UPI split tool