How many electronvolts are in one calorie?

One thermochemical calorie equals approximately 2.61144×10¹⁹ eV. This comes from 1 cal = 4.184 J and 1 J = 6.24150907×10¹⁸ eV (the reciprocal of the elementary charge, fixed exactly in 2019).

Which calorie definition does this tool use?

This tool uses the thermochemical calorie, defined as exactly 4.184 J. This is the most common calorie in chemistry and physics. The international table calorie (4.1868 J) differs slightly — it is used in steam engineering but is rarely needed in particle physics contexts.

Why are the eV values so large for small calorie amounts?

The electronvolt is an extremely tiny unit (1 eV ≈ 1.6×10⁻¹⁹ J), so even a small calorie — already a very small amount of energy — corresponds to roughly 2.6×10¹⁹ eV. Scientific notation is essential to express these results accurately.

What is the difference between eV, keV, MeV, and GeV?

1 keV = 1,000 eV; 1 MeV = 10⁶ eV; 1 GeV = 10⁹ eV. Atomic electron binding energies are a few eV, X-rays carry keV energies, nuclear reactions involve MeV, and particle accelerators reach GeV and beyond.

How do I enter scientific notation?

Use standard e-notation: for 1.5×10⁻³ type "1.5e-3". The tool accepts this format directly in either input field.

Calories to Electronvolts Converter

Enter energy in thermochemical calories to get electronvolts (eV), keV, MeV, and GeV — or enter eV to convert back. Uses 1 cal = 4.184 J = 2.6114×10¹⁹ eV.

Energy Converter

Energy in Calories (cal)

Electronvolts (eV)

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Kiloelectronvolts (keV)

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Megaelectronvolts (MeV)

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Gigaelectronvolts (GeV)

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1 cal = 4.184 J = 2.61144×10¹&sup9; eV

cal ↔ eV Reference Table

Common calorie values and their electronvolt equivalents

Calories (cal)	Electronvolts (eV)	Scale

1 cal = 4.184 J (thermochemical, exact) | 1 eV = 1.602176634×10⁻¹&sup9; J (exact, 2019 SI)

Summary

This converter turns thermochemical calories (cal) into electronvolts (eV), kiloelectronvolts (keV), megaelectronvolts (MeV), and gigaelectronvolts (GeV). The conversion uses 1 cal = 4.184 J exactly, combined with the 2019 SI definition 1 eV = 1.602176634×10⁻¹⁹ J — giving 1 cal = 2.61144×10¹⁹ eV. The tool is bidirectional: enter calories to see eV results, or enter eV to get the calorie equivalent. A reference table at the bottom shows common cal↔eV values.

How it works

Select the conversion direction: cal → eV or eV → cal.
Type any numeric value — whole numbers, decimals, or scientific notation (e.g. 1.5e-3).
Results in eV, keV, MeV, and GeV appear instantly (or joules and calories in reverse).
Click any result field to copy its value to the clipboard.
The reference table below shows common calorie-to-eV conversions for quick lookup.

Use cases

Convert bond dissociation energies in cal/mol to per-molecule eV for quantum chemistry.
Cross-reference calorimeter measurements in calories against particle-physics eV scales.
Check thermodynamic reaction enthalpies expressed in calories against eV equivalents.
Convert activation energies in thermochemical calories to electronvolts for materials science.
Bridge chemistry (calorie) and physics (electronvolt) notation in interdisciplinary research.
Verify textbook energy values given in calories against their eV equivalents.

Frequently Asked Questions

Last updated: 2026-06-19 · Reviewed by Nham Vu