Energy Converter
Convert between joules, calories, BTU, kilowatt-hours, and more
Energy Converter
Common Conversions
Understanding Energy Units
🔬 Joules (J) - SI Unit
The standard unit of energy in physics. One joule is the energy needed to lift a small apple about 1 meter against Earth's gravity.
🍎 Calories (cal) - Food Energy
Small calorie: energy to heat 1g of water by 1°C. Food labels show "Calories" (capital C) = kilocalories (kcal) = 1,000 small calories.
🔥 BTU - Heating & Cooling
British Thermal Unit: energy to heat 1 pound of water by 1°F. Used for HVAC systems, furnaces, and air conditioners.
⚡ kWh - Electricity
Kilowatt-hour: energy consumed by a 1,000-watt appliance in 1 hour. Used for electricity billing worldwide.
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⚠️ Important Disclaimer
This tool provides estimates for informational purposes only. Results should not be relied upon for important decisions. Always consult with a qualified professional for advice specific to your situation.
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Frequently Asked Questions
What's the difference between calories and Calories?
Small "c" calories (cal) are the scientific unit. Capital "C" Calories on food labels are actually kilocalories (kcal), which equal 1,000 small calories.
How do I convert kWh to calories?
1 kWh = 860,421 calories (or 860.421 kcal). So if you consume 1 kWh of electricity, that's equivalent to about 860 food Calories of energy.
What is BTU used for?
BTU (British Thermal Unit) is commonly used to rate heating and cooling systems. For example, a 10,000 BTU air conditioner can remove 10,000 BTU of heat per hour.
How much energy is in food?
Food energy is measured in Calories (kcal): 1g of carbs = 4 kcal, 1g of protein = 4 kcal, 1g of fat = 9 kcal. A 2,000 Calorie diet equals 8,368 kilojoules.