Definition –The unit kilowatt-hour (kWh) is a measure of energy that represents the amount of power (1 kW) consumed over one hour (1 h). Although it is not a standard unit in any formal system, it is widely used in electrical applications.


In simpler terms, the kWh is the product of power consumed by the load in kW and the number of hours it draws power from the supply system. 

Electrical Unit(Kwh)  =  Load (in Kw) X No. of running hours

kWh to units conversion

The following mathematical expression is used to convert the kWh into units.

1-kwh-is-equal to-1-unit

For example, if an electrical load consumes 100kWh, it consumes 100 units.

Conversion of Kw into Kwh

Step 1 Note down running kW of the electrical equipment
Step 2 Note down the running hours(h)
Step 3 Multiply kW and hour, you will get kWh.

Example – 1

A heater with a rating of 20 kW runs for 5 hours; what will be the unit consumed?

kWh= kW X hours
= 20 X 5
kWh = 100 kWh

Example -2

A 55 kW induction motor draws 40 kW from the supply source and runs for 3 hours; calculate the unit(kWh) drawn by the motor.

kWh= kW X hours
= 40 X 3
kWh = 120 kWh

Conversion of Kwh into Kw

KW can be found by simply dividing the kWh by working hours.

Step 1 Note down the kWh of the electrical equipment
Step 2 Note down the running hours(h)
Step 3 – Divide kWh by running hour. You will get kW.

Load (in Kw) = No. Of Units (Kwh) / No. of working hours (h)

Example – 1

An induction motor draws 1000 kWh(units) in 5 hours; calculate the kW of the motor.

kWh = kW X hour


Example – 2

Three bulbs of rating 100 watt, 200 watt and 500 watts run for 2, 3 and 4 hours respectively, calculate the energy consumed by these bulbs.

Bulbs Rating
100 watt =0.1kW
200 watt =0.2kW
500 watt =0.5kW

kWh = kW X hour

kWh= 0.1 x 2+0.2 X3+0.5 x4
kWh= 0.2+0.6+2
KWh=2.8 kWh= 2.8 Units

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