How to Convert Electronvolts to Kilocalories (eV to kcal)
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 kilocalories by hand, with examples and a quick-reference table.
The conversion
To convert electronvolts to kilocalories, multiply the value by 3.829294e-23. To go the other way, divide by the same number (or multiply by 2.611447e+22). Because the factor is tiny, scientific notation keeps the numbers manageable.
Kilocalories = electronvolts × 3.829294e-23
Worked examples
- 3 eV = 1.148788e-22 kcal
- 12.5 eV = 4.786618e-22 kcal
- 75 eV = 2.871971e-21 kcal
Electronvolts to Kilocalories table
| Electronvolts | Kilocalories |
|---|---|
| 1 eV | 3.829294e-23 kcal |
| 2 eV | 7.658588e-23 kcal |
| 5 eV | 1.914647e-22 kcal |
| 10 eV | 3.829294e-22 kcal |
| 20 eV | 7.658588e-22 kcal |
| 25 eV | 9.573235e-22 kcal |
| 50 eV | 1.914647e-21 kcal |
| 100 eV | 3.829294e-21 kcal |
| 250 eV | 9.573235e-21 kcal |
| 500 eV | 1.914647e-20 kcal |
| 1,000 eV | 3.829294e-20 kcal |
Common questions
Is eV to kcal 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 Kilocalories 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.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
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.
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.
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
For any value, use the Electronvolts to Kilocalories Converter or browse all energy converters.
Run your own numbers: Electronvolts to Kilocalories Converter