Watts to Joules Converter

Use this converter to easily convert between Watts and Joules. Also supports MilliWatts (mW), KiloWatts (KW), MegaWatts (MW), KiloJoules (KJ), and MegaJoules (MJ).

Share converter:

Embed this tool:
get code     

    Quick navigation:
  1. How many Watts equal one Joule?
  2. Difference between Watts and Joules
  3. How to convert Watts to Joules
  4. Watts to Joules conversion table

    How many Watts equal one Joule?

Exactly 1 Watt equal one Joule per second. This comes from the definition of the Watt, which is a unit of power used to quantify the rate of energy transfer. In the International System of Units (SI) it is defined as a derived unit of 1 Joule per second [1] with a symbol W. The formula for calculating Energy in Joules (J) is:

E(J) = P(W) x t(s)

where E is the energy in Joules, P is the power in Watts, and t is the time in seconds. Our Watts to Joules converter also supports conversion from MilliWatts (mW), Watts (W), KiloWatts (KW), and MegaWatts (MW) to KiloJoules (kJ) and MegaJoules (mJ) per second, per minute or per hour.

    Difference between Watts and Joules

Watts are units of power while Joules are units of energy and there is often confusion about the difference between the terms power and energy. Energy is the work performed over a period of time while Power is the rate of delivery of energy, meaning work performed per unit of time. The equivalent energy unit for Joules is Watt hours.

More energy will be used in a given time-frame with a higher level of power, therefore, for a set energy level, a longer period results in higher energy consumption under the same power, while a higher level of power would spend the available energy in less time.

    How to convert Watts to Joules

In order to convert Watts - a unit of power, to Joules - a unit of energy, we need to know a third variable - the time period of interest. Therefore, in our Joules to Watts converter you have two inputs: one for power (mW, W, KW, MW) and one for time (sec, min, hours).

Then you need to follow the definition the Watt as 1 Joule per second and perform the mathematical transformation required to convert the time units to seconds and the power unit to Watts. For example, if your input is in KiloWatt, you need to divide by 1,000 in order to get the result in Joules.

Watts to Joules conversion example

Sample task: convert 2 Watts of power maintained over an hour to Joules. Solution:

Watts * 3600 = Joules
2 Watts * 3,600 = 7,200 Joules
End result:
2 Watts is equal to 7,200 Joules

    Watts to Joules conversion table

W to J conversion table
1 W 1 J
2 W 2 J
3 W 3 J
4 W 4 J
5 W 5 J
6 W 6 J
7 W 7 J
8 W 8 J
9 W 9 J
10 W 10 J
20 W 20 J
30 W 30 J
40 W 40 J
50 W 50 J
60 W 60 J
70 W 70 J
80 W 80 J
90 W 90 J
100 W 100 J
200 W 200 J
300 W 300 J
400 W 400 J
500 W 500 J
600 W 600 J
700 W 700 J
800 W 800 J
900 W 900 J
1,000 W 1,000 J


1 NIST Special Publication 330 (2008) - "The International System of Units (SI)", edited by Barry N.Taylor and Ambler Thompson

2 International Organization for Standardization (1993). ISO Standards Handbook: Quantities and units (3rd edition). Geneva: ISO. ISBN 92-67-10185-4.

Cite this converter & page

If you'd like to cite this online converter resource and information as provided on the page, you can use the following citation:
Georgiev G.Z., "Watts to Joules Converter", [online] Available at: https://www.gigacalculator.com/converters/convert-watts-to-joules.php URL [Accessed Date: 29 May, 2023].