Convert Kilojoule to British Thermal Unit (kJ → BTU)

Converting kilojoules to BTU 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 0.947817

   The conversion factor from kJ to BTU is 0.947817. Multiply your value by this number.
3. 3
   Read the result in BTU

   The result is your value in BTU (BTU).

Multiply the value in kilojoules by 0.947817. For the reverse direction, multiply by 1.055056.

• ✓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 British Thermal Unit?

The British thermal unit (BTU) equals approximately 1,055.06 joules and is the standard unit in American HVAC, gas appliances, and air-conditioner ratings. Originally defined as the heat needed to raise 1 pound of water by 1°F, the BTU is the imperial counterpart to the calorie. American gas utilities measure delivered heat in BTUs or therms (1 therm = 100,000 BTU), and air conditioners are rated by their cooling capacity in BTU per hour (a typical window AC is 5,000–12,000 BTU/h, central AC for a medium home is 24,000–60,000 BTU/h). Furnaces are similarly rated. The BTU relates to the joule (1 BTU ≈ 1,055 J), the calorie (1 BTU ≈ 252 cal), the watt-hour (1 BTU ≈ 0.293 Wh), and the therm (100,000 BTU = 1 therm). Outside the United States, the BTU is rare; metric countries use kilojoules or kilowatt-hours for the same applications.

• US air-conditioner sizing
• US heating-system capacity
• Natural gas billing in some US regions