Convert Kilojoules to Electronvolts - Energy Converter
This tool converts energy values from kilojoules (kJ) to electronvolts (eV) using SI-traceable physical constants. The conversion relies on the fixed value of the elementary charge and the SI definition of the joule.
The conversion is exact in terms of the defined constants used: 1 kilojoule = 1000 joules, and 1 electronvolt is the energy gained by an electron passing through a potential difference of one volt. For practical work, we show the numeric factor and guidance on choosing significant figures based on measurement and computational limits.
Interactive converter unavailable for this calculator.
We could not resolve compatible units for this experience. Please verify the slug follows the pattern `from-unit-to-unit-converter`.
Methodology
We use the internationally adopted constants and SI definitions. The elementary charge (e) is taken from the International System of Units (SI) definitions and CODATA/NIST references to convert joules to electronvolts.
Conversion process: convert kilojoules to joules by multiplying by 1000, then divide by the joule-equivalent of one electronvolt (1 eV = 1.602176634e-19 J) to get eV. For high-precision work, carry at least 9–12 significant digits through intermediate calculations and round only at the final step.
Worked examples
Example 1: 1 kJ = 1 × 1000 J = 1000 / 1.602176634e-19 eV ≈ 6.241509074e21 eV.
Example 2: 2.5 kJ → 2.5 × 6.241509074e21 eV ≈ 1.5603772685e22 eV (report with appropriate significant figures for your context).
Key takeaways
Use this converter for fast, SI-traceable transformations between kJ and eV. For metrology, calibration, or regulatory reporting ensure you document constants and rounding rules used.
When interoperability with instruments or standards bodies is required, reference the NIST/CODATA/BIPM values cited below and preserve sufficient significant digits to avoid round-off error in downstream calculations.
Expert Q&A
What numeric factor does this converter use?
This converter uses 1 eV = 1.602176634e-19 J (exact by the SI definition of the elementary charge) and 1 kJ = 1000 J. Therefore 1 kJ = 6.241509074e21 eV (approximate numeric factor derived from exact constants).
How many significant figures should I keep?
Keep at least as many significant figures as your least-precise input or instrument. For laboratory and computational work, preserving 9–12 significant digits through intermediate steps prevents meaningful round-off error; round only for reporting.
Are these values traceable to standards bodies?
Yes. The conversion is based on SI definitions and internationally recommended constants maintained by NIST, CODATA, and BIPM. For formal traceability in calibration and compliance contexts, cite the same sources and record the version of the constants used.
Can I convert very large or small energies without overflow/underflow?
Numeric limits depend on your computing environment. Values near 1e308 may overflow double-precision floating point. For extremely large/small values, use arbitrary-precision libraries or scientific notation and document the numeric format used.
Does instrument calibration affect the conversion?
The mathematical conversion is independent of instrument calibration, but measurement uncertainty from instruments (calorimeters, spectrometers) must be propagated through the conversion. Record instrument calibration certificates and include uncertainty when reporting converted values.
When should I reference official standards?
Reference official standards for metrology, certification, or regulatory reporting. Use NIST, BIPM, or national metrology institute publications when traceability or auditability is required.
Sources & citations
- NIST Reference on Fundamental Physical Constants — https://physics.nist.gov/cuu/Constants/index.html
- BIPM SI Brochure (International System of Units) — https://www.bipm.org/en/publications/si-brochure
- CODATA Recommended Values of the Fundamental Physical Constants — https://physics.nist.gov/cuu/Constants/index.html