Watt-seconds to Kilojoules Conversion

Enter the energy in watt-seconds below to get the value converted to kilojoules.

Results in Kilojoules:
Loading content.
1 Ws = 0.001 kJ

How to Convert Watt-seconds to Kilojoules

To convert a watt-second measurement to a kilojoule measurement, divide the energy by the conversion ratio.

Since one kilojoule is equal to 1,000 watt-seconds, you can use this simple formula to convert:

kilojoules = watt-seconds ÷ 1,000

The energy in kilojoules is equal to the watt-seconds divided by 1,000.

For example, here's how to convert 500 watt-seconds to kilojoules using the formula above.
500 Ws = (500 ÷ 1,000) = 0.5 kJ

Watt-seconds and kilojoules are both units used to measure energy. Keep reading to learn more about each unit of measure.


The watt-second is a measure of electrical energy equal to one watt of power over a one second period. One watt-second is equal to 1/3,600 of a watt-hour or one joule.

Watt-seconds are usually abbreviated as Ws, although the formally adopted expression is W·s. The abbreviation W s is also sometimes used. For example, 1 watt-second can be written as 1 Ws, 1 W·s, or 1 W s.

In formal expressions, the centered dot (·) or space is used to separate units used to indicate multiplication in an expression and to avoid conflicting prefixes being misinterpreted as a unit symbol.[1]


One kilojoule is equal to 1,000 joules, which are the energy equal to the force on an object of one newton at a distance of one meter.

The kilojoule is a multiple of the joule, which is the SI derived unit for energy. In the metric system, "kilo" is the prefix for 103. Kilojoules can be abbreviated as kJ; for example, 1 kilojoule can be written as 1 kJ.

Watt-second to Kilojoule Conversion Table

Watt-second measurements converted to kilojoules
Watt-seconds Kilojoules
1 Ws 0.001 kJ
2 Ws 0.002 kJ
3 Ws 0.003 kJ
4 Ws 0.004 kJ
5 Ws 0.005 kJ
6 Ws 0.006 kJ
7 Ws 0.007 kJ
8 Ws 0.008 kJ
9 Ws 0.009 kJ
10 Ws 0.01 kJ
20 Ws 0.02 kJ
30 Ws 0.03 kJ
40 Ws 0.04 kJ
50 Ws 0.05 kJ
60 Ws 0.06 kJ
70 Ws 0.07 kJ
80 Ws 0.08 kJ
90 Ws 0.09 kJ
100 Ws 0.1 kJ
200 Ws 0.2 kJ
300 Ws 0.3 kJ
400 Ws 0.4 kJ
500 Ws 0.5 kJ
600 Ws 0.6 kJ
700 Ws 0.7 kJ
800 Ws 0.8 kJ
900 Ws 0.9 kJ
1,000 Ws 1 kJ


  1. Bureau International des Poids et Mesures, The International System of Units (SI), 9th edition, 2019, https://www.bipm.org/documents/20126/41483022/SI-Brochure-9-EN.pdf

More Watt-second & Kilojoule Conversions