How to Convert Electronvolts to Kilojoules (eV to kJ)
Energy conversions link food labels in kJ and kcal, SP Group bills in kWh and air-conditioner capacity in BTU. This guide shows how to convert electronvolts into kilojoules by hand, with examples and a quick-reference table.
The conversion
To convert electronvolts to kilojoules, multiply the value by 1.602177e-22. To go the other way, divide by the same number (or multiply by 6.241509e+21). Because the factor is tiny, scientific notation keeps the numbers manageable.
Kilojoules = electronvolts × 1.602177e-22
Worked examples
- 3 eV = 4.806530e-22 kJ
- 12.5 eV = 2.002721e-21 kJ
- 75 eV = 1.201632e-20 kJ
Electronvolts to Kilojoules table
| Electronvolts | Kilojoules |
|---|---|
| 1 eV | 1.602177e-22 kJ |
| 2 eV | 3.204353e-22 kJ |
| 5 eV | 8.010883e-22 kJ |
| 10 eV | 1.602177e-21 kJ |
| 20 eV | 3.204353e-21 kJ |
| 25 eV | 4.005442e-21 kJ |
| 50 eV | 8.010883e-21 kJ |
| 100 eV | 1.602177e-20 kJ |
| 250 eV | 4.005442e-20 kJ |
| 500 eV | 8.010883e-20 kJ |
| 1,000 eV | 1.602177e-19 kJ |
Common questions
Is eV to kJ exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Kilojoules to Electronvolts converter.
Mistakes to avoid
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Background
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
For any value, use the Electronvolts to Kilojoules Converter or browse all energy converters.
Run your own numbers: Electronvolts to Kilojoules Converter