Photon Wavelength and Energy Converter
Convert vacuum wavelength, frequency and energy per photon using the exact SI defining constants. Select independent input and output units.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Relate vacuum wavelength to frequency with the speed of light. Multiply frequency by Planck’s constant for the energy of one photon; divide by the exact joule-per-electronvolt factor for eV.
c=λf; E=hf=hc/λ
Worked example
A vacuum wavelength of 500 nm corresponds to 599.584916 THz and approximately 2.479684 eV per photon.
Assumptions and input details
All entered quantities are strictly positive. Base-unit input is supported from 1e−100 to 1e100, with finite result limits. Uses exact c=299792458 m/s, h=6.62607015e−34 J s and 1 eV=1.602176634e−19 J. Decimal output is rounded. Wavelength is in vacuum: a wavelength inside a material needs its refractive index to recover vacuum wavelength. Energy is per photon, not source power or radiation dose.
References: NIST SI defining constants · NIST fundamental constants
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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