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What is kWh (Kilowatt hour)? – Definition, Formula and Calculation

What is Kilowatt hour (kWh)? – Definition, Formula, Example and Calculation

Kilowatt-hour (kWh) is a unit of energy commonly used to measure electricity consumption. It is defined as the energy consumed by a device with a power rating of 1 kilowatt (kW) over a period of one hour.

1 kWh = 1000 Watts per Hour

Good to know:

  • kWh is the exact thing for which electric supply providers charge you.
  • One kilo Watt hour (kWh) is also known as one unit of electricity.
  • 1 kWh is also represented by 1 B.O.T unit where B.O.T = Board of Trade Unit.
  • 1 kilo Watt hour = 36 x105 … Joule or Watt-seconds = 3.6 MJ
  • Overall, 1kWh = 1000Wh = 36 × 105 … Joule or Watt-seconds = 3.6 MJ = 1 Board of Trade Unit = 1 B.O.T Unit = 1 Unit of Electricity.

Other Conversion and related terms to kWh

  • Symbol of kWh = kW⋅h or kW h
  • 1 kWh = SI units: 3.6 MJ
  • 1 kWh = English Engineering units: ≈ 2,655,224 ft⋅lbf
  • 1 kWh = CGS units: 3.6×1013 erg
  • 1 kWh = British Gravitational units: ≈ 85,429,300 ft⋅pdl

What is kWh - Kilowatt hour?

To understand kWh, it is important to first understand what power is. Power is the rate at which energy is used or transferred, measured in watts (W) or kilowatts (kW). A device with a power rating of 1 kW consumes 1,000 watts of electric power.

Electricity consumption is typically measured in kilowatt-hours (kWh), which is a measure of the amount of energy used over a period of time. For example, if a device with a power rating of 1 kW is used for 1 hour, it will consume 1 kWh of energy.

Kilowatt-hours are commonly used by utilities to bill customers for their electricity usage. The cost of electricity is typically expressed in cents per kWh, with the total cost being calculated by multiplying the number of kWh used by the cost per kWh.

To calculate the kWh usage of a device, you need to know its power rating and the amount of time it has been used. For example, a device with a power rating of 1 kW that has been used for 5 hours would consume 5 kWh of energy.

It’s important to note that while kWh is a commonly used unit of measurement for electricity consumption, it is not the only unit used. Other units include megawatt-hours (MWh) and gigawatt-hours (GWh), which are used to measure the energy consumption of large-scale power plants and other industrial facilities.

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kWh Formula & Calculation.

E = P × t

kWh = kW × time in hours

kWh = Watts × time in hrs ÷ 1000

kWh = Wh ÷ 1000


What is the amount of power consumed in kWh if a 5kW load is connected for 3 hours.


Putting the values in the kWh formula

kWh = 5kW × 3 hours = 15kWh

Measurement of kWh

kWh meter (also known as an energy meter) is used to measure the power consumption by consumers. The power supply provider installs an analog or digital energy meter at the user end which record the power consumption at a specific time period. Finally, they charge the consumer based on the units consumed in a month.

Cost of Electricity Bill based on kWh

kWh is the exact thing for which the power supply provider charge the consumer. Let’s see how to calculate the electricity bill based on kWh consumption.

For example, if a consumer consumes 2kW daily (24 hours) a day and the rate of 1kWh is 5¢. Thus, the total cost of electricity for 1 month (30 days) would be:

= 2kW × 24 Hours x 30 Days = 1440 kWh.

= 1440 × 5¢ = 72$

In short, kWh is a unit of measurement used to quantify electricity consumption over a period of time. It is commonly used by utilities to bill customers for their electricity usage, and is calculated based on the power rating of a device and the amount of time it has been used. Understanding kWh is an important aspect of managing energy usage and reducing electricity costs.

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