Energy Converter
Convert joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU and more. Type in any unit; all others update instantly.
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About This Converter
This energy converter supports 10 units spanning scientific, nutritional, electrical, and engineering systems. Every calculation passes through a Joule base, so results are precise whether you are comparing food calories to kilojoules, converting electricity bills from kilowatt-hours, working with BTU ratings for HVAC, or dealing with particle physics in electronvolts. It is a handy tool for physics, nutrition, engineering, and everyday energy comparisons.
FAQ
Calorie vs kilocalorie — what's the difference?
A calorie (cal) — sometimes called a "small calorie" — is the energy needed to raise 1 gram of water by 1 degree Celsius. A kilocalorie (kcal), also known as a "food Calorie" (capital C), equals 1,000 calories. When food labels say "200 Calories," they mean 200 kcal.
How do I convert kWh to joules?
1 kilowatt-hour (kWh) = 3,600,000 joules (J). Since 1 kW = 1,000 J/s and 1 hour = 3,600 seconds: 1,000 × 3,600 = 3,600,000 J.
What is a BTU?
A BTU (British Thermal Unit) is the amount of energy needed to raise 1 pound of water by 1 degree Fahrenheit. It equals approximately 1,055 joules. BTUs are commonly used to rate heating and cooling systems (furnaces, air conditioners) and fuel energy content.
How much energy is 1 electronvolt?
1 electronvolt (eV) = 1.602176634 × 10⁻¹⁹ joules (exact, per the 2019 SI redefinition). It is the energy gained by one electron moving through a 1-volt potential difference. While tiny in everyday terms, eV is the standard unit in particle physics and semiconductor science.