Convert between Joules, Calories, kWh, BTU, and more energy units. Perfect for physics, nutrition, and engineering calculations.
Last updated: March 2026 | By Patchworkr Team
Energy is the capacity to do work or produce heat. It exists in many forms including kinetic, potential, thermal, chemical, and electrical energy. Energy can be converted between forms but cannot be created or destroyed (law of conservation of energy).
Different units measure energy in different contexts: Joules in physics, Calories in nutrition, kWh for electricity, and BTU in heating/cooling. Understanding these conversions is essential for science, engineering, and everyday applications.
Lowercase "calorie" (cal) is the scientific unit. Uppercase "Calorie" (Cal) in food labels actually means kilocalorie (kcal), which is 1000 calories. So 1 food Calorie = 1 kcal = 1000 cal.
Different fields developed their own units historically. Physics uses Joules, nutrition uses Calories, electricity uses kWh, and HVAC uses BTU. Each unit is convenient for its specific scale and application.
One kWh is the energy used by a 1000-watt device running for 1 hour. It's equivalent to 3.6 million Joules or about 860 kilocalories. Typical homes use 20-30 kWh per day.
An electronvolt (eV) is the energy gained by an electron moving through a 1-volt potential. It's extremely small (1.602×10⁻¹⁹ J) and used in atomic and particle physics.
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