An electronvolt is the energy gained by an electron across one volt.
Electronvolts to Calories Converter — eV to cal
Convert Electronvolt (eV) to Calorie (cal) using the exact conversion factor (1 electronvolt = 3.829294e-20 calorie). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Electronvolts to Calories converter
Converter
Energy Converter
Convert joules, calories, kilowatt-hours, BTU, electronvolts, therms, and mechanical work units.
Context values
Some unit families need one extra value for a physically accurate result.
A thermochemical calorie is 4.184 joules.
Result = input x 1.60217663e-19 / 4.184.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Electronvolts to Calories
Electronvolt and Calorie both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Electronvolt is typically associated with standard unit throughout particle physics, atomic physics, and chemistry worldwide, while Calorie is typically associated with nutrition labeling in the US and several other countries still commonly uses the kilocalorie (as 'Calorie').
Formula
calories = electronvolts × 3.829294e-20
This factor comes from each unit's defined relationship to the category's base unit: 1 electronvolt equals 1.602177e-19 base units, and 1 calorie equals 4.184 base units, so dividing one by the other gives the direct electronvolt-to-calorie factor of 3.829294e-20.
Simple example
1 eV × 3.829294e-20 = 3.829294e-20 cal
1 electronvolt = 3.829294e-20 calories.
Real-world example
100 eV × 3.829294e-20 = 3.829294e-18 cal
100 electronvolts = 3.829294e-18 calories.
Conversion table
| Electronvolt (eV) | Calorie (cal) |
|---|---|
| 1 eV | 3.829294e-20 cal |
| 10 eV | 3.829294e-19 cal |
| 100 eV | 3.829294e-18 cal |
| 500 eV | 1.914647e-17 cal |
| 1,000 eV | 3.829294e-17 cal |
| 2,000 eV | 7.658588e-17 cal |
Reverse conversion: Calorie to Electronvolt
3.829294e-20 cal × 2.611447e+19 = 0.9999999848 eV
3.829294e-20 calories = 0.9999999848 electronvolts.
electronvolts = calories × 2.611447e+19
For a page dedicated to this direction, see Calorie to Electronvolt.
Electronvolt vs. Calorie
| Aspect | Electronvolt | Calorie |
|---|---|---|
| Family | non-SI unit accepted for use with the SI, common in physics | Non-SI unit (limited use with SI) |
| Typical use | Particle physics (particle accelerator energies are often quoted in GeV or TeV) | Food energy labeling (as kilocalories, often written 'Calories') |
| Where it's used | Standard unit throughout particle physics, atomic physics, and chemistry worldwide | Nutrition labeling in the US and several other countries still commonly uses the kilocalorie (as 'Calorie') |
Understanding the Electronvolt
Electronvolt (eV) measures energy. The energy gained by a single electron accelerated through an electric potential difference of one volt — a very small amount of energy, exactly 1.602176634 × 10⁻¹⁹ joules. It is classified as a non-SI unit accepted for use with the SI, common in physics.
Where it's used: Standard unit throughout particle physics, atomic physics, and chemistry worldwide
Uses of the Electronvolt today
- Particle physics (particle accelerator energies are often quoted in GeV or TeV)
- Atomic and molecular energy levels
- Semiconductor band-gap energies
Understanding the Calorie
Calorie (cal) measures energy. The thermochemical calorie used in this converter is defined as exactly 4.184 joules. It is classified as a Non-SI unit (limited use with SI).
Where it's used: Nutrition labeling in the US and several other countries still commonly uses the kilocalorie (as 'Calorie')
Calorie vs. Calorie (kilocalorie). Food labels' capitalized 'Calorie' is actually one kilocalorie (1,000 small calories) — a long-standing labeling convention that causes frequent confusion.
Uses of the Calorie today
- Food energy labeling (as kilocalories, often written 'Calories')
- Historical chemistry and thermodynamics contexts
History of the Calorie
The calorie was originally defined in the early 19th century as the heat needed to raise one gram of water by one degree Celsius, but different scientific traditions defined it at slightly different reference temperatures, producing several close but non-identical 'calorie' values historically (15 °C calorie, mean calorie, thermochemical calorie).
To resolve this ambiguity, the thermochemical calorie was fixed by convention at exactly 4.184 joules; the very similar International Table calorie is fixed at exactly 4.1868 joules. The nutritional 'Calorie' seen on food labels is actually a kilocalorie (1,000 calories).
Historical origin. Calorie was not the invention of a single named person; it developed through the process described above.
Electronvolt — sources
- BIPM SI Brochure, 9th edition — Electronvolt listed as a non-SI unit accepted for use with the SI, with its exact value fixed via the elementary charge.
Calorie — sources
- NIST Special Publication 811 — Documents the thermochemical calorie's exact joule equivalence.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many calories are in 1 electronvolt?
1 electronvolt equals 3.829294e-20 calories, using the exact defined conversion factor rather than an estimate.
How do I convert electronvolt to calorie?
Multiply the electronvolt value by 3.829294e-20. The converter above does this instantly to whatever precision you set.
How do I convert calorie back to electronvolt?
Use the reverse factor: 1 calorie equals 2.611447e+19 electronvolts. You can also use the swap control in the converter above to flip the direction instantly.
What is a electronvolt?
Electronvolt (eV) measures energy. The energy gained by a single electron accelerated through an electric potential difference of one volt — a very small amount of energy, exactly 1.602176634 × 10⁻¹⁹ joules. It is classified as a non-SI unit accepted for use with the SI, common in physics.
What is a calorie?
Calorie (cal) measures energy. The thermochemical calorie used in this converter is defined as exactly 4.184 joules. It is classified as a Non-SI unit (limited use with SI).
Is the electronvolt to calorie conversion exact?
Yes. The thermochemical calorie used in this converter is defined as exactly 4.184 joules. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between calorie vs. calorie (kilocalorie)?
Food labels' capitalized 'Calorie' is actually one kilocalorie (1,000 small calories) — a long-standing labeling convention that causes frequent confusion.
Where is the electronvolt still used today?
Standard unit throughout particle physics, atomic physics, and chemistry worldwide