How many calories are in one electronvolt?

One electronvolt equals approximately 3.82930×10⁻²⁰ thermochemical calories. This comes from 1 eV = 1.602176634×10⁻¹⁹ J (exact, 2019 SI) and 1 cal = 4.184 J (exact), so 1 eV = 1.602176634×10⁻¹⁹ / 4.184 cal.

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) is used in steam engineering but is rarely needed alongside electronvolts.

Why are the calorie values so small for eV inputs?

The electronvolt (1 eV ≈ 1.6×10⁻¹⁹ J) is an extremely tiny unit of energy, far smaller than a calorie (4.184 J). So even a large number of eV corresponds to a very small fraction of a calorie. Scientific notation is essential here.

How do I enter keV, MeV, or GeV values?

Use the unit selector to pick keV, MeV, or GeV before typing your value. The tool converts the selected unit to eV first, then to calories. Alternatively, enter the raw eV value in scientific notation (e.g. 1e6 for 1 MeV).

How do I enter scientific notation?

Use standard e-notation: for 1.5×10⁶ type "1.5e6". The tool accepts this format directly in the input field.

Electronvolts to Calories Converter

Enter energy in electronvolts (eV), keV, MeV, or GeV to get thermochemical calories instantly — or enter calories to convert back. Uses 1 eV = 1.602176634×10⁻¹⁹ J = 3.8293×10⁻²⁰ cal.

Energy Converter

Input Unit

Energy in Electronvolts (eV)

Thermochemical Calories (cal)

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Joules (J)

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1 eV = 1.602176634×10⁻¹&sup9; J = 3.8293×10⁻²⁰ cal

eV ↔ cal Reference Table

Common electronvolt values and their calorie equivalents

Electronvolts (eV)	Calories (cal)	Context

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

Summary

This converter turns electronvolts (eV) into thermochemical calories (cal). It also accepts keV, MeV, and GeV inputs for particle and nuclear physics work. The conversion uses the exact 2019 SI definition: 1 eV = 1.602176634×10⁻¹⁹ J, combined with 1 cal = 4.184 J — giving 1 eV = 3.82930×10⁻²⁰ cal. The tool is bidirectional: enter eV to get calories, or enter calories to get eV. A reference table shows common eV↔cal values.

How it works

Select the input unit: eV, keV, MeV, or GeV — or switch to cal → eV direction.
Type any numeric value, including scientific notation (e.g. 1.5e6).
The calorie equivalent appears instantly in the result field.
Click any result field to copy its value to the clipboard.
The reference table below shows common eV-to-calorie conversions for quick lookup.

Use cases

Convert particle physics energies in eV or MeV to thermochemical calories for cross-disciplinary comparisons.
Translate X-ray photon energies in keV to calories for radiation dosimetry estimates.
Cross-reference nuclear reaction Q-values in MeV against calorie-based calorimetry data.
Check textbook energy values given in eV against their calorie equivalents.
Bridge chemistry (calorie) and physics (electronvolt) notation in interdisciplinary research.
Convert activation energies from eV (quantum chemistry output) to calories for thermodynamic tables.

Frequently Asked Questions

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