Convert energy units — joules, calories, kilowatt-hours, BTU, kilojoules.
| Unit | Name | Value |
|---|---|---|
| J | Joule | 1055.06 |
| kJ | Kilojoule | 1.05506 |
| cal | Calorie | 252.16539 |
| kcal | Kilocalorie (Cal) | 0.25216539 |
| kWh | Kilowatt-hour | 0.00029307222 |
Formula: Kilojoule = BTU × 1.055
Multiply any btu value by 1.055 to get kilojoule.
Reverse: BTU = Kilojoule × 0.9478
Common btu values — factor: 1 BTU = 1.055 kJ
| BTU (BTU) | Kilojoule (kJ) | Context |
|---|---|---|
| 1 BTU | 1.055 kJ | Match |
| 10 BTU | 10.55 kJ | 10 BTU |
| 100 BTU | 105.5 kJ | Space heater second |
| 1,000 BTU | 1,055 kJ | 1 kBTU |
| 3,412 BTU | 3,600 kJ | 1 kWh |
| 1e+04 BTU | 1.055e+04 kJ | 10 kBTU |
| 1e+05 BTU | 1.055e+05 kJ | 1 therm |
| 1e+06 BTU | 1.055e+06 kJ | 1 MMBTU |
| 1e+07 BTU | 1.055e+07 kJ | 10 MMBTU |
| 1e+08 BTU | 1.055e+08 kJ | 100 MMBTU |
| 1.000e+09 BTU | 1.055e+09 kJ | 1 billion BTU |
| 1.000e+10 BTU | 1.055e+10 kJ | 10 billion BTU |
| 1.000e+12 BTU | 1.055e+12 kJ | 1 quad fraction |
| 1.000e+15 BTU | 1.055e+15 kJ | 1 quad |
| 1.000e+18 BTU | 1.055e+18 kJ | 1000 quads |
BTU × 1.055 = kJ. Almost 1:1 — very close.
One BTU is just slightly more than one kilojoule.
kJ ÷ 1.055 = BTU.
Sizes heating and cooling systems rated in BTU/hour for US buildings.
Certifies boiler output and efficiency ratings in BTU/hour.
Prices natural gas supply and usage in BTU and therms.
Calculates heating loads and heat loss in BTU for US properties.
Rates commercial refrigeration and ice-making capacity in BTU.
Specifies heat exchanger capacity and furnace output in BTU/hour.
The British Thermal Unit (BTU) is the traditional Imperial energy unit, defined as the heat required to raise 1 pound of water by 1°F. It equals 1,055.06 joules and has been used since the 19th century in heating, air conditioning, and gas billing.
BTU remains dominant in US HVAC: air conditioners and heaters are rated in BTU/hour. Natural gas is priced in therms (100,000 BTU) in the US. Furnaces are rated in BTU/hour output.
Interesting fact: A typical US home furnace is rated at 80,000–120,000 BTU/hour. One BTU is roughly the energy released by burning one kitchen match. The US natural gas pipeline system delivers about 25 quadrillion BTU (quads) per year.
The kilojoule (kJ) equals 1,000 joules and is the practical energy unit for food, chemistry, and heating applications in metric countries. Food energy labels in Australia, Europe, and most of the world use kilojoules.
A dietary calorie (kcal) equals 4.184 kJ. A can of soda contains about 600 kJ. The specific heat of water (4.184 kJ/kg·°C) means heating 1 liter of water by 1°C requires 4.184 kJ.
Interesting fact: An average adult needs about 8,000-10,000 kJ (2,000-2,400 kcal) per day. Running a marathon burns approximately 12,500 kJ.
Converting btu to kilojoule is common across energy, nutrition, engineering, and science. Different sectors use different energy units — joules in physics, kcal in nutrition, kWh in electricity, and BTU in HVAC — making accurate conversion essential for cross-disciplinary work and international comparisons.
Quick reference: 5 BTU = 5.275 kJ and 10 BTU = 10.55 kJ. Reverse: 1 kJ = 0.9478 BTU. Exact factor: 1 BTU = 1.055 kJ.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.