Convert British Thermal Unit to Kilojoule (BTU → kJ)
The British thermal unit is the standard for American HVAC systems, gas appliances, and air-conditioner ratings.
British Thermal Unit to Kilojoule Conversion Table
10 common values| British Thermal Unit | Kilojoule |
|---|---|
| 1 BTU | 1.055056 kJ |
| 10 BTU | 10.550558 kJ |
| 100 BTU | 105.50558 kJ |
| 500 BTU | 527.52792 kJ |
| 1,000 BTU | 1,055.0558 kJ |
| 5,000 BTU | 5,275.2792 kJ |
| 10,000 BTU | 10,550.558 kJ |
| 50,000 BTU | 52,752.793 kJ |
| 100,000 BTU | 105,505.59 kJ |
| 500,000 BTU | 527,527.93 kJ |
How to Convert British Thermal Unit to Kilojoule Manually
Step by StepConverting BTU to kilojoules is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.
- 1Take your value in BTUStart with the number of BTU (BTU) you want to convert.
- 2Multiply by 1.055056The conversion factor from BTU to kJ is 1.055056. Multiply your value by this number.
- 3Read the result in kilojoulesThe result is your value in kilojoules (kJ).
Formula
Multiply the value in BTU by 1.055056. For the reverse direction, multiply by 0.947817.
kJ = BTU × 1.055056BTU = kJ × 0.947817Tips
Use these in everyday conversions- 1 BTU = 1055.06 J = 0.293 Wh.
- BTU/h (power) and BTU (energy) are different — don't confuse.
- Tons of refrigeration: 12,000 BTU/h = 1 ton AC.
Common Mistakes
Avoid these- Confusing BTU and BTU/h — energy vs power.
- Using kcal when BTU is requested in HVAC specs.
- Treating all BTUs as exact — definitions vary (IT, thermochemical, etc.).
About British Thermal Unit and Kilojoule
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
Window AC: 5000–12,000 BTU/h. Central AC: 24,000–60,000 BTU/h. Home furnace: 60,000–100,000 BTU/h.
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
100 g chocolate: ~2100 kJ. EU daily intake (adult): ~8400 kJ. Tesla Model 3 battery: ~270 MJ = 270,000 kJ.