Energy Converter
Quick Reference
• 1 kWh = 3,600,000 joules
• 1 calorie = 4.184 joules
• 1 kcal = 1,000 calories
• 1 BTU = 1,055.06 joules
• 1 Wh = 3,600 joules
• 1 kJ = 1,000 joules
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One Kilowatt-Hour Runs a Lot of Life
The central anchor: 1 kWh equals 3.6 million joules — 3.6 megajoules — the energy a 1,000-watt appliance burns in one hour. From there, real comparisons: an efficient EV travels roughly 6 km on one kWh; a 12,000 BTU window air conditioner draws about 3.5 kW while running; a 2,000-kcal daily diet is 8.37 megajoules, because the 'calorie' on food packaging is actually a kilocalorie, 4,184 joules each.
Kilowatt-Hours Are Not Kilowatts, and BTUs Come per Hour
Two spec-sheet traps account for most confusion. Energy and power are different quantities: a 12 kWh battery stores energy, a 12 kW charger delivers power — the first says how much, the second how fast, and dividing one by the other gives charging time. Similarly, air conditioners are marketed with BTU figures that are really BTU per hour; comparing that number to a heater rated in raw BTU misreads capacity by a factor of 3600. Joules never appear on consumer bills — but they sit underneath every figure that does.
About Energy Converter
Energy arrives in a different unit for every audience: electricity is billed in kilowatt-hours, heating and cooling equipment in the US is rated in BTUs, food labels count kilocalories, and physics lives in joules. Anyone comparing across these — an EV owner reading consumption, a shopper sizing an air conditioner against a room, a dieter converting a food label — needs the same bridge between units that measure the same physical quantity.
How to Use
Step 1
Enter the energy value
Step 2
Select the unit you're converting from
Step 3
Select the unit you're converting to
Step 4
Click 'Convert' to see the result
Step 5
Perfect for physics, nutrition, and electricity
Features & Benefits
- ✅Convert between 10 energy units
- ✅SI: joule, kilojoule, megajoule
- ✅Calories: calorie, kilocalorie (food calories)
- ✅Electrical: watt-hour, kilowatt-hour
- ✅Imperial: BTU, foot-pound
- ✅High precision results
- ✅Quick reference table
- ✅100% browser-based
- ✅100% free
FAQs
What is a kilocalorie (kcal)?
1 kilocalorie = 1,000 calories = 4,184 joules. Food labels often show 'Calories' (capital C) which are actually kilocalories.
How many joules in a kWh?
1 kWh = 3,600,000 joules (3.6 megajoules). This is the unit used for electricity billing.
What is a BTU?
BTU (British Thermal Unit) = 1,055.06 joules. It's commonly used for heating and cooling systems in the US.