Exact tool to convert Joules, Calories, kWh, and BTU. Indispensable for physics, chemistry, and electricity.
Energy is one of the most versatile quantities in physics — the same fundamental unit, the joule, describes both the caloric value of food and the mechanical work of an engine or the electrical energy consumed by a house. This universality comes from the Law of Conservation of Energy, experimentally proven in the mid-19th century by British brewer-scientist James Prescott Joule, who demonstrated that heat and mechanical work are equivalent, convertible forms of energy. One of the most confusing energy conversion cases is precisely the food calorie: the "calorie" printed on food labels is technically a kilocalorie (1,000 physical calories) — a historical naming confusion that persists to this day. Meanwhile, the most common everyday electrical unit, the kilowatt-hour used on power bills, is mathematically equivalent to 3.6 million joules, a connection most people never realize. This converter handles conversions between joules, calories, kilowatt-hours, BTU (British Thermal Unit, common in air conditioning specifications), and other energy units, essential for nutritionists calculating diets, mechanical and electrical engineers sizing systems, and consumers trying to understand and compare the energy consumption of different appliances or heating sources.
1 thermochemical calorie is equivalent to 4.184 Joules.
The kilowatt-hour is the standard unit used in electricity bills.
1 kWh is equal to 3,600,000 Joules.
British Thermal Unit, commonly used in air conditioning units.
It needs the internet to open, but performs calculations directly in your browser.