Converter Tool
Energy Converter
Convert between Joules, calories, watt-hours, and kilowatt-hours. 100% client-side — no data is sent to any server.
Scientific, food energy
Food energy, nutrition
⚡ Quick Reference
•1 kJ = 1000 J
•1 kcal = 4184 J
•1 Wh = 3600 J
•1 kWh = 3,600,000 J
•1 cal = 4.184 J
•1 kcal = 4.184 kJ
🔒 All processing happens in your browser. No data is sent to any server.
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How to use this Energy Converter
Converting energy units is simple with our free online tool. Enter the value you want to convert, select the From unit (J, kJ, cal, kcal, Wh, or kWh), and choose the To unit.
The conversion happens automatically. You can also load common energy values like smartphone usage or household consumption with a single click, or copy the result to your clipboard.
What this energy converter does
- ✓Six energy units — Convert between J, kJ, cal, kcal, Wh, and kWh.
- ✓Accurate conversions — Uses precise mathematical formulas with standard conversion factors.
- ✓Common energy values — Quickly load typical energy values for everyday appliances.
- ✓Swap units — Easily swap between From and To units.
- ✓Copy result — Copy the converted value with one click.
- ✓100% client-side — All processing happens in your browser. No data is sent to servers.
Common use cases
- •Convert food calories (kcal) to kilojoules for nutritional tracking
- •Calculate electricity consumption in kWh for billing and budgeting
- •Convert battery capacity between Wh and Joules for technical specifications
- •Calculate energy efficiency and consumption for appliances
- •Convert energy units in physics and engineering calculations
- •Track and compare energy usage across different devices and systems
⚡ Energy Reference
Everyday Energy
- Smartphone daily: ~10 Wh (36 kJ)
- LED bulb 10hr: ~100 Wh (360 kJ)
- Laptop daily: ~500 Wh (1.8 MJ)
- Refrigerator daily: ~1.5 kWh (5.4 MJ)
Unit Relationships
- 1 kcal = 4.184 kJ = 4184 J
- 1 kWh = 3.6 MJ = 860 kcal
- 1 Wh = 3600 J = 0.86 kcal