How many kilocalories are in one electronvolt?

One electronvolt equals approximately 3.82930×10⁻²³ thermochemical kilocalories. This comes from 1 eV = 1.602176634×10⁻¹⁹ J (exact, 2019 SI) and 1 kcal = 4184 J (exact thermochemical), so 1 eV = 1.602176634×10⁻¹⁹ / 4184 kcal.

Which kilocalorie definition does this tool use?

This tool uses the thermochemical kilocalorie, defined as exactly 4184 J (1000 × thermochemical calorie of 4.184 J). This is the standard unit in chemistry and physics. The international table kilocalorie (4186.8 J) is used in steam engineering but is rarely encountered alongside electronvolts.

Why are the kcal 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 kilocalorie (4184 J). So even a large number of eV corresponds to a very small fraction of a kilocalorie. 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 kcal. 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.

What is the difference between eV to cal and eV to kcal?

One kilocalorie equals 1000 small calories, so the eV-to-kcal value is exactly 1000 times smaller than the eV-to-cal value. 1 eV ≈ 3.8293×10⁻²⁰ cal, and 1 eV ≈ 3.8293×10⁻²³ kcal.

Electronvolts to Kilocalories Converter

Enter energy in electronvolts (eV), keV, MeV, or GeV to get thermochemical kilocalories instantly — or enter kcal to convert back. Uses 1 eV = 1.602176634×10⁻¹⁹ J = 3.8293×10⁻²³ kcal.

Energy Converter

Input Unit

Energy in Electronvolts (eV)

Kilocalories (kcal)

—

Calories (cal)

—

Joules (J)

—

Copied!

1 eV = 1.602176634×10⁻¹&sup9; J = 3.8293×10⁻²³ kcal

eV ↔ kcal Reference Table

Common electronvolt values and their kilocalorie equivalents

Electronvolts (eV)	Kilocalories (kcal)	Context

1 eV = 1.602176634×10⁻¹&sup9; J (exact, 2019 SI) | 1 kcal = 4184 J (thermochemical, exact)

Summary

This converter turns electronvolts (eV) into thermochemical kilocalories (kcal). It 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 kcal = 4184 J — giving 1 eV ≈ 3.82930×10⁻²³ kcal. The tool is bidirectional: enter eV to get kcal, or enter kcal to get eV. A reference table shows common eV↔kcal values.

How it works

Select the input unit: eV, keV, MeV, or GeV — or switch to kcal → eV direction.
Type any numeric value, including scientific notation (e.g. 1.5e6).
The kilocalorie 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-kcal conversions for quick lookup.

Use cases

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

Frequently Asked Questions

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