What is 1 unit of electricity? (1 unit = 1 kWh)
One unit on your bill is one kilowatt-hour (kWh), the energy that a 1,000-watt load uses in one hour. Also called kilowatt-hour, kWh, unit of electricity.
- Plain English
- Official sources
- Bill terms A–Z
Unit on your bill
Your meter counts energy in units. One unit is one kilowatt-hour (kWh).
The bill shows the previous reading, the present reading and the difference. The difference is the units you used.
Units = watts x hours / 1,000. A 1,000 W heater for 2 hours uses 2 units. A 100 W bulb for 10 hours uses 1 unit.
Most charges on the bill are worked out from these units: the energy charge, many fuel surcharges and some duties.
Read your meter on the same day each month. Then you can check the units on the bill.
Units for everyday loads
| This | Uses |
|---|---|
| 1 unit | 1 kWh |
| 1,000 watts for 1 hour | 1 unit |
| 100 watts for 10 hours | 1 unit |
| 1,500 W geyser for 30 minutes | 0.75 unit |
| 75 W fan for 12 hours | 0.9 unit |
Related terms
Official sources
- Tamil Nadu Tax on Consumption or Sale of Electricity Act, 2003 (Bill text with Statement of Objects and Reasons, Government of Tamil Nadu), s.2(15)
“means one kilowatt hours of energy”
Read on 17 October 2026. Your State regulator’s rules and your discom’s bill have the final word.