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.

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.

Electronvolts to Calories Converter

Q: 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.

Q: 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).

About Converting Electronvolts to Calories

Electronvolt and Calorie both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. 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
50 eV	1.914647e-18 cal
100 eV	3.829294e-18 cal
500 eV	1.914647e-17 cal
1,000 eV	3.829294e-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.

Electronvolts to Calories Converter — eV to cal

Engineering Converter