How Many Units Does an AC, Fan or Fridge Use? From Watts to Your Bill
Turn an appliance’s watts and hours into units (kWh), then see what those units really add to your bill once BERC’s 2026 slabs and the lifeline rule apply.
Published 29 October 2026
The short answer
1 unit is 1 kWh: 1,000 watts running for one hour, so units = watts × hours ÷ 1,000. An AC rated 1,500 W running 8 hours a day uses up to 360 units a month. In a home that already uses 150 units, that raises the bill from ৳1,213.80 to ৳5,359.31, because the extra units fall in the dearer slabs.
What one unit of electricity means
One unit on your bill is one kilowatt-hour (kWh): the electricity a 1,000-watt appliance uses running for one hour. So one formula covers every appliance:
Units = watts × hours of use ÷ 1,000
For a month, multiply the daily units by the number of days; this guide uses 30. A 75 W fan running 10 hours a day uses 75 × 10 ÷ 1,000 = 0.75 units a day, or 0.75 × 30 = 22.5 units a month.
Where to find an appliance’s watts
Use the “Rated power” or “Power input” in watts on the appliance’s label or in its manual. For an air conditioner, use the power input in watts, not the cooling capacity in BTU or tons.
The label shows what the appliance draws at full power. AC and fridge compressors cycle on and off once the room or cabinet is cool, and an inverter AC draws less then, so this formula gives an upper limit; real use is usually lower. If a fridge label gives kWh per year, divide it by 12 for the monthly units.
Units a month: examples
The watts below are examples only; check your own appliance’s label before you work it out.
| Appliance | Watts | Hours a day | Units a month |
|---|---|---|---|
| LED bulb | 10 | 6 | 1.8 |
| Ceiling fan | 75 | 10 | 22.5 |
| TV | 100 | 5 | 15 |
| Rice cooker | 700 | 1 | 21 |
| Air conditioner | 1,500 | 8 | 360 |
One air conditioner can use several times as many units as everything else together. An hour less of AC saves far more than switching off bulbs or fans.
What it adds to the bill: extra units land in higher slabs
Home electricity is priced in slabs. A new appliance’s units are added on top of what you already use, so they are charged at the higher slabs’ rates, not at your average rate. From the June 2026 billing month, BERC’s price for each extra unit, with 5% VAT:
| Units in the month | Per unit (৳) | With VAT (৳) |
|---|---|---|
| 1–75 | 5.26 | 5.52 |
| 76–200 | 8.50 | 8.93 |
| 201–300 | 9.10 | 9.56 |
| 301–400 | 9.62 | 10.10 |
| 401–600 | 15.01 | 15.76 |
| Above 600 | 17.35 | 18.22 |
Example: an AC in a 150-unit home
A home uses 150 units a month without an AC (2 kW sanctioned load, single-phase, postpaid meter, ৳40 meter rent, 5% VAT). Its bill is ৳1,213.80. Add a 1,500 W AC running 8 hours a day, which is 360 more units, 510 in all, and the bill becomes ৳5,359.31.
So the AC adds ৳4,145.51, about ৳11.52 for each of its units. Its units are numbers 151 to 510 in the month, and many of them fall in the 401–600 slab at ৳15.01 a unit. The same AC in a home that uses less would cost less per unit.
Example: a fan in a lifeline home
A home that uses 40 units a month pays the lifeline rate (৳4.63) on all of them: a bill of ৳324.66. Add a fan using 22.5 units and the month comes to 62.5 units. That is over 50, so the whole month moves to the normal slabs and the bill becomes ৳475.39: ৳150.73 more for the fan’s 22.5 units. Near the lifeline limit a single unit matters: 50 units cost ৳373.28 and 51 units cost ৳411.87.
Where cutting back saves the most
- Above 400 units a month, each unit costs about ৳15.76 with VAT, and ৳18.22 above 600. Every unit cut there saves almost three times as much as a unit in the first slab (৳5.52).
- Cut the hours of big appliances. Running a 1,500 W AC one hour less a day saves 1.5 units a day, 45 units a month.
- Near the lifeline limit, try to stay at 50 units or less: at 51 units every unit is billed at the higher rate.
Work out your own bill in a minute
- Take the watts from the appliance’s label and decide how many hours a day it runs.
- Monthly units = watts × hours ÷ 1,000 × 30.
- In the Electricity Bill Calculator, enter your usual month’s units, then add the appliance’s units and calculate again. The difference between the two bills is what the appliance really costs.
The calculator comes pre-filled with BERC’s rates, the demand charge, meter rent and VAT, each with its date and source, and you can change any figure that differs on your company’s bill. The numbers you enter never leave your device.
Sources and dates
Electricity rates are from BERC’s order of 3 June 2026 and its 4 June 2026 revision, checked on 29 October 2026. The 5% VAT and ৳40 meter rent are as reported; the full list of sources is on the calculator page. The appliance watts are examples, not any brand’s or model’s rating.