Energy Converter
Convert between different units of energy Convert between 21 different units instantly with our free online tool.
Formula: 1 J × 0.001 = 0.001 kJ
Available Energy Units
21 units supported for instant conversion
About Energy Conversion
Our free online energy converter helps you quickly and accurately convert between 21 different units of energy. Whether you're a student, professional, or simply need everyday conversions, you get instant, precise results with the formula displayed.
Convert between different units of energy This converter supports both metric and imperial units, making it ideal for international use. All conversions use internationally recognized standards and formulas.
Did You Know?
The energy released by a single lightning bolt is about 1–5 GJ (gigajoules), enough to power a 100-watt light bulb for about 3 months.
A typical adult needs about 2,000 kcal (8.37 MJ) per day. Running a marathon burns roughly 2,500–3,000 kcal — about 1.5 days of resting energy.
1 gram of matter, converted to energy via E=mc², releases 9×10¹³ joules — equivalent to about 21 kilotons of TNT, the size of the Hiroshima bomb.
1 liter of petrol contains about 34 MJ of chemical energy. A single AA battery stores only about 15,000 joules — petrol is about 2,200× more energy-dense.
The global human energy consumption is about 580 EJ (exajoules) per year. The Sun delivers about 1.74 × 10¹⁷ joules to Earth every second — covering a year of human energy use in about 0.1 seconds.
Why Use Our Energy Converter?
Instant Results
Conversions update as you type — no button clicks needed.
High Precision
Uses internationally standardized conversion factors (SI & NIST).
21+ Units
Convert between 21 energy units used around the world.
API & AI Ready
REST API and MCP server let apps and AI assistants convert programmatically.
Common Energy Conversion Table
Quick reference: Joule (J) to other common units.
| Joule (J) | Kilojoule (kJ) | Megajoule (MJ) | Gigajoule (GJ) | Calorie (cal) |
|---|---|---|---|---|
| 1 | 0.001 | 1.000000e-6 | 1.000000e-9 | 0.2390057 |
| 2 | 0.002 | 2.000000e-6 | 2.000000e-9 | 0.4780115 |
| 5 | 0.005 | 5.000000e-6 | 5.000000e-9 | 1.195029 |
| 10 | 0.01 | 1.000000e-5 | 1.000000e-8 | 2.390057 |
| 25 | 0.025 | 2.500000e-5 | 2.500000e-8 | 5.975143 |
| 50 | 0.05 | 5.000000e-5 | 5.000000e-8 | 11.95029 |
| 100 | 0.1 | 1.000000e-4 | 1.000000e-7 | 23.90057 |
How to Use This Energy Converter
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