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: Joule = BTU × 1055
Multiply any btu value by 1055 to get joule.
Reverse: BTU = Joule × 0.0009478
Common btu values — factor: 1 BTU = 1055 J
| BTU (BTU) | Joule (J) | Context |
|---|---|---|
| 1 BTU | 1,055 J | Match |
| 10 BTU | 1.055e+04 J | 10 BTU |
| 100 BTU | 1.055e+05 J | Space heater second |
| 1,000 BTU | 1.055e+06 J | 1 kBTU |
| 3,412 BTU | 3.6e+06 J | 1 kWh |
| 1e+04 BTU | 1.055e+07 J | 10 kBTU |
| 1e+05 BTU | 1.055e+08 J | 1 therm |
| 1e+06 BTU | 1.055e+09 J | 1 MMBTU |
| 1e+07 BTU | 1.055e+10 J | 10 MMBTU |
| 1e+08 BTU | 1.055e+11 J | 100 MMBTU |
| 1.000e+09 BTU | 1.055e+12 J | 1 billion BTU |
| 1.000e+10 BTU | 1.055e+13 J | 10 billion BTU |
| 1.000e+12 BTU | 1.055e+15 J | 1 quad fraction |
| 1.000e+15 BTU | 1.055e+18 J | 1 quad |
| 1.000e+18 BTU | 1.055e+21 J | 1000 quads |
1 BTU = 1055 J. Memorize for instant estimates.
Use 1055 as a quick mental multiplier.
Multiply result by 0.0009478 to recover the original BTU value.
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 joule is the SI derived unit of energy, work, and heat, defined as the energy transferred when a force of one newton moves an object one meter. It was named after James Prescott Joule, the English physicist who established the mechanical equivalent of heat in the 1840s.
The joule is universal in physics and engineering: kinetic energy (½mv²), potential energy (mgh), electrical energy (VIt), and heat are all measured in joules. One joule is the energy needed to lift a 100g apple one meter against gravity.
Interesting fact: The human heart expends about 1 joule of energy with each beat. A 60-watt light bulb uses 60 joules every second. The entire energy released by a 1-megaton nuclear weapon equals about 4.18 × 10¹⁵ joules.
Converting btu to joule 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 = 5275 J and 10 BTU = 10,550 J. Reverse: 1 J = 0.0009478 BTU. Exact factor: 1 BTU = 1055 J.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.