Kilowatt hours and joules calculator
This page contains a calculator for converting kilowatt hours (kWh) to joules (J). The formula is shown together with
other useful information and a worked example. Note that 1 kilowatt is 1000 watts.
The SI units of time is seconds, but there are occasions when it makes sense to use other units for reasons of easily
understood communication. For example, in everyday speech it’s often much easier, and very likely better understood,
to say “one and a quarter hours” rather than 4500 seconds.
Enter all figures without commas. For example, enter 2,400 as 2400.
Calculate energy used (J)
The equation for kilowatts hours to joules is given above right.
Example: A heater rated at 2 kilowatts runs for 1 hour and 30
minutes. What is this in kWh and how much energy was used?
In kWh this is simply 2 kW x 1.5 hours = 3 kWh. Entering 3 kWh into
the calculator and clicking Calculate we can see that the energy used
was 10800000 J.
Kilowatt hours to joules calculator
Energy used = kWh x 3600000 J
Where:
kWh = kilowatt hours
1 kilowatt = 1000 watts
J = joules (the SI unit of energy)
Kilowatt hours to
joules calculator
Kilowatt hours and joules calculator
This page contains a calculator for converting kilowatt hours
(kWh) to joules (J). The formula is shown together with other
useful information and a worked example. Note that 1 kilowatt is
1000 watts.
The SI units of time is seconds, but there are occasions when it
makes sense to use other units for reasons of easily understood
communication. For example, in everyday speech it’s often much
easier, and very likely better understood, to say “one and a
quarter hours” rather than 4500 seconds.
Enter all figures without commas. For example, enter 2,400 as
2400.
Calculate energy used (J)
The equation for kilowatts hours to joules is given below.
Example: A heater rated at 2 kilowatts runs for 1 hour and 30
minutes. What is this in kWh and how much energy was used?
In kWh this is simply 2 kW x 1.5 hours = 3 kWh. Entering 3 kWh
into the calculator and clicking Calculate we can see that the
energy used was 10800000 J.
Energy used = kWh x 3600000 J
Where:
kWh = kilowatt hours
1 kilowatt = 1000 watts
J = joules (the SI unit of energy)
