Convert Kilojoule to Kilowatt-Hour (kJ → kWh)

Converting kilojoules to kilowatt-hours is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in kilojoules

   Start with the number of kilojoules (kJ) you want to convert.
2. 2
   Multiply by 0.000278

   The conversion factor from kJ to kWh is 0.000278. Multiply your value by this number.
3. 3
   Read the result in kilowatt-hours

   The result is your value in kilowatt-hours (kWh).

Multiply the value in kilojoules by 0.000278. For the reverse direction, multiply by 3,600.

• ✓1 kJ = 1000 J = 0.239 kcal.
• ✓EU nutrition labels must show both kJ and kcal.
• ✓For quick conversion: kcal × 4.2 = kJ.

• ✗Assuming European labels use kcal only — they use both kJ and kcal.
• ✗Confusing kJ with kW (power).
• ✗Using kcal when kJ is requested in scientific context.

What is the Kilojoule?

The kilojoule equals 1,000 joules and is the standard unit on European nutrition labels and in mid-scale chemical and physical calculations. EU regulations require food packaging to display energy in kilojoules (typically with kilocalories also shown for consumer familiarity): a chocolate bar might show '2,100 kJ / 500 kcal' per 100 g. The kilojoule is also common in chemistry (bond energies), electrical engineering (capacitor storage), and small-mechanical-energy contexts. A car battery typically stores about 1,800 kJ; lifting a person 1 meter requires roughly 0.7 kJ. The kilojoule relates to the joule (1,000 J = 1 kJ), the kilocalorie (1 kcal = 4.184 kJ), the watt-hour (1 kWh = 3,600 kJ), and the megajoule (1,000 kJ = 1 MJ). The conversion factor 4.184 (kJ per kcal) is one of the most-used numbers in nutrition labeling.

• EU and UK nutrition labels
• Mechanical work in engineering
• Battery capacity in vehicles

What is the Kilowatt-Hour?

The kilowatt-hour equals 1,000 watt-hours (3.6 megajoules) and is the universal billing unit for residential electricity consumption around the world. A typical US household uses about 800–1,000 kWh per month; a refrigerator consumes 1–2 kWh per day, an LED bulb at 10 W for 10 hours uses 0.1 kWh, and a Tesla Model 3 has a 75 kWh battery (about 250–350 miles of range). Electric utility rates are quoted in cents per kWh — typical US residential rates are 11–25 ¢/kWh, while industrial rates are lower. The kilowatt-hour is essential in renewable-energy planning: solar panel output, wind farm production, and grid-scale storage are all rated in kWh or MWh (megawatt-hours). It relates to the watt-hour (1,000 Wh = 1 kWh), the joule (1 kWh = 3.6 MJ), the BTU (1 kWh ≈ 3,412 BTU), and the megawatt-hour (1,000 kWh = 1 MWh).

• Electricity billing globally
• EV battery capacity specifications
• Home solar and battery storage