How many electronvolts are in 1 calorie?

1 calorie equals 2.611447e+19 electronvolts, using the exact defined conversion factor rather than an estimate.

How do I convert calorie to electronvolt?

Multiply the calorie value by 2.611447e+19. The converter above does this instantly to whatever precision you set.

How do I convert electronvolt back to calorie?

Use the reverse factor: 1 electronvolt equals 3.829294e-20 calories. You can also use the swap control in the converter above to flip the direction instantly.

Is the calorie to electronvolt conversion exact?

Yes. 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. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.

Calories to Electronvolts Converter

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).

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.

About Converting Calories to Electronvolts

Calorie and Electronvolt 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. Calorie is typically associated with nutrition labeling in the US and several other countries still commonly uses the kilocalorie (as 'Calorie'), while Electronvolt is typically associated with standard unit throughout particle physics, atomic physics, and chemistry worldwide.

Formula

electronvolts = calories × 2.611447e+19

This factor comes from each unit's defined relationship to the category's base unit: 1 calorie equals 4.184 base units, and 1 electronvolt equals 1.602177e-19 base units, so dividing one by the other gives the direct calorie-to-electronvolt factor of 2.611447e+19.

Simple example

1 cal × 2.611447e+19 = 2.611447e+19 eV

1 calorie = 2.611447e+19 electronvolts.

Real-world example

100 cal × 2.611447e+19 = 2.611447e+21 eV

100 calories = 2.611447e+21 electronvolts.

Conversion table

Calorie (cal)	Electronvolt (eV)
1 cal	2.611447e+19 eV
10 cal	2.611447e+20 eV
50 cal	1.305724e+21 eV
100 cal	2.611447e+21 eV
500 cal	1.305724e+22 eV
1,000 cal	2.611447e+22 eV

Reverse conversion: Electronvolt to Calorie

2.611447e+19 eV × 3.829294e-20 = 0.9999998481 cal

2.611447e+19 electronvolts = 0.9999998481 calories.

calories = electronvolts × 3.829294e-20

For a page dedicated to this direction, see Electronvolt to Calorie.

Calorie vs. Electronvolt

Aspect	Calorie	Electronvolt
Family	Non-SI unit (limited use with SI)	non-SI unit accepted for use with the SI, common in physics
Typical use	Food energy labeling (as kilocalories, often written 'Calories')	Particle physics (particle accelerator energies are often quoted in GeV or TeV)
Where it's used	Nutrition labeling in the US and several other countries still commonly uses the kilocalorie (as 'Calorie')	Standard unit throughout particle physics, atomic physics, and chemistry worldwide

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.

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

Calorie — sources

NIST Special Publication 811 — Documents the thermochemical calorie's exact joule equivalence.

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.

Calories to Electronvolts Converter — cal to eV

Engineering Converter