Convert energy units — joules, calories, kilowatt-hours, BTU, kilojoules.
| Unit | Name | Value |
|---|---|---|
| kJ | Kilojoule | 0.001 |
| cal | Calorie | 0.23900574 |
| kcal | Kilocalorie (Cal) | 0.00023900574 |
| kWh | Kilowatt-hour | 2.7777778e-7 |
| BTU | BTU | 0.00094781339 |
Formula: BTU = Joule × 0.0009478
Multiply any joule value by 0.0009478 to get btu.
Reverse: Joule = BTU × 1055
Common joule values — factor: 1 J = 0.0009478 BTU
| Joule (J) | BTU (BTU) | Context |
|---|---|---|
| 0.001 J | 9.478e-07 BTU | 1 mJ |
| 0.1 J | 9.478e-05 BTU | Heartbeat |
| 1 J | 0.0009478 BTU | Lift apple 10cm |
| 4.184 J | 0.003966 BTU | 1 calorie |
| 100 J | 0.09478 BTU | Sprinting 1 sec |
| 1,000 J | 0.9478 BTU | 1 kJ |
| 4,184 J | 3.966 BTU | 1 kcal food |
| 1e+04 J | 9.478 BTU | 10 kJ |
| 1e+05 J | 94.78 BTU | 100 kJ |
| 1.055e+06 J | 1,000 BTU | 1 BTU |
| 3.6e+06 J | 3,412 BTU | 1 kWh |
| 1e+08 J | 9.478e+04 BTU | ~100 MJ |
| 1.000e+09 J | 9.478e+05 BTU | 1 GJ |
| 1.000e+12 J | 9.478e+08 BTU | 1 TJ |
| 1.000e+15 J | 9.478e+11 BTU | 1 PJ |
1 J = 0.0009478 BTU. Memorize for instant estimates.
Use 0.0009478 as a quick mental multiplier.
Multiply result by 1055 to recover the original J value.
Uses joules as the SI unit for all energy, work, and heat calculations.
Calculates kinetic energy, potential energy, and work in joules.
Measures reaction enthalpies, bond energies, and heat of solution in joules.
Converts between power (watts) and energy (joules = watt-seconds).
Measures fracture energy and impact resistance in joules.
Applies the first law of thermodynamics with energy in joules.
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.
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.
Converting joule to btu 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 J = 0.004739 BTU and 10 J = 0.009478 BTU. Reverse: 1 BTU = 1055 J. Exact factor: 1 J = 0.0009478 BTU.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.