Convert between different energy units including joules, calories, BTU, kilowatt-hours, electron volts, and more with instant calculations and accurate conversion factors.
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A kilocalorie (kcal) is equal to 1,000 calories. The 'calories' listed on food labels are actually kilocalories. One food calorie equals 4,186.8 joules.
To convert joules to calories, divide by 4.184. For example, 1,000 joules equals approximately 239.0 calories. This uses the thermochemical calorie definition.
One British Thermal Unit (BTU IT) equals 1,055.06 joules. BTU is commonly used in heating and cooling applications, while joules are the SI unit for energy.
One kilowatt-hour (kWh) equals 3,600,000 joules or 3.6 megajoules. This is the amount of energy consumed by a 1,000-watt device running for one hour.
An electron volt (eV) is a very small unit of energy used in atomic and nuclear physics. One eV equals approximately 1.602 × 10⁻¹⁹ joules.
Different BTU types (IT, th, mean, 39°F, 59°F) exist due to varying temperature conditions and standards. The International Table (IT) BTU is most commonly used today.
A therm is a unit of energy equal to 100,000 BTU or approximately 105.5 megajoules. It's commonly used by natural gas utilities for billing purposes.
These conversions use internationally accepted conversion factors and are accurate to many decimal places. The precision shown depends on the units being converted and their inherent measurement standards.