Online Heat Unit Converter
| # | Unit name | Symbol | Conversion result |
|---|
| Scenario | J | kJ | Kilocalorie | kWh |
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About the Online Heat Unit Converter
Tool Introduction
This tool supports real-time conversion between 18 common heat and energy units. Heat (energy) is a core concept in physics and nutrition, referring to the total kinetic energy of molecular thermal motion within an object, with the joule (J) as the base unit in the International System of Units. Whether interpreting nutrition labels (kilocalorie ↔ kilojoule), converting electricity billing units (kilowatt-hour ↔ joule), designing HVAC systems (BTU ↔ joule), or conducting physical chemistry experiments (calorie ↔ joule), enter a value to get an accurate result immediately.
Metric/International System of Units
Joule (J): the base unit of energy in the International System of Units, 1 J = 1 N·m (work done by a force of 1 newton over a distance of 1 meter). Kilojoule (kJ) = 1000 J, megajoule (MJ) = 10⁶ J, gigajoule (GJ) = 10⁹ J. Erg is a CGS unit, 1 erg = 10⁻⁷ J. These units are widely used in physics, chemistry, engineering thermodynamics, and other fields.
Calorie-related units
Calorie (cal): defined as the heat required to raise the temperature of 1 gram of pure water by 1°C at standard atmospheric pressure; modern international standard: 1 cal = 4.184 J. Kilocalorie (kcal), also called "large calorie", = 1000 cal = 4184 J, is a common unit on food nutrition labels. The term "Calorie" (with a capital C) on food labels usually actually means kilocalorie, so be sure to distinguish them.
Electricity units
Watt-hour (Wh) = 3600 J, kilowatt-hour (kWh) = 3.6×10⁶ J, which is commonly called "1 unit of electricity". Electronvolt (eV) is a common unit in microphysics, referring to the energy gained by one electron passing through a potential difference of 1 volt; 1 eV ≈ 1.602×10⁻¹⁹ J. Household appliance electricity consumption is generally measured in kWh; for example, a 1000W air conditioner running for 1 hour consumes 1 kWh of energy.
British units
British Thermal Unit (BTU): defined as the heat required to raise the temperature of 1 pound of water by 1°F; 1 BTU ≈ 1055.06 J. Widely used in HVAC in the UK and US; for example, household air conditioner cooling capacity is often expressed in BTU/h. Foot-pound (ft·lb): work done by a force of 1 pound-force over a distance of 1 foot; 1 ft·lb ≈ 1.3558 J. Horsepower-hour (hp·h) ≈ 2.685×10⁶ J. Therm is a natural gas billing unit; 1 therm = 100000 BTU.
Other special units
Ton of TNT equivalent: commonly used to measure explosion energy; 1 ton of TNT ≈ 4.184×10⁹ J. Nuclear weapon yields are usually expressed in kilotons (kt) or megatons (Mt) of TNT. These units are also widely used in nuclear physics, seismology (seismic moment), and military industries.
Privacy and Security
All conversion logic is performed locally in your browser; no values are uploaded to a server. You can use it with confidence, without worrying about data leaks.
Tips
1. After entering any value, all units are automatically converted in real time; 2. The heat gauge at the top shows the current energy's visual position within the 1 J - 1 MJ range in real time (logarithmic scale); 3. Click the circular button in the middle to swap the source and target units with one click; 4. The common conversions section provides typical scenarios for one-click switching; 5. The "Common energy reference points" table at the bottom lists typical scenarios from a single photon to a nuclear explosion for quick comparison.