Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Unit Converters
Wavelength to Photon Energy Converter
E (J) = 6.62607015×10⁻³⁴ × 2.99792458×10⁸ / λ(m). Divide by 1.602e-19 for eV.
E = hc / λ. A 550 nm green photon is about 2.25 eV. X-rays are picometers and keV. The page uses the SI values of h and c, vacuum, one photon — not a laser pulse energy.
Wavelength (nm)
nm → eV
2.2543 eV
Green light near 550 nm is about 2.25 eV. The page uses vacuum hc.
- Joules
- 3.6117e-19
- Wavelength
- 550 nm
Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
Wavelength (nm)
The “Wavelength (nm)” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
E = hc / λ. A 550 nm green photon is about 2.25 eV. X-rays are picometers and keV. The page uses the SI values of h and c, vacuum, one photon — not a laser pulse energy. E (J) = 6.62607015×10⁻³⁴ × 2.99792458×10⁸ / λ(m). Divide by 1.602e-19 for eV. Example: 550 nm → ~2.25 eV. 1 nm X-ray-ish → 1.24 keV.
E (J) = 6.62607015×10⁻³⁴ × 2.99792458×10⁸ / λ(m). Divide by 1.602e-19 for eV.
Example: 550 nm → ~2.25 eV. 1 nm X-ray-ish → 1.24 keV.
When to use this Wavelength to Photon Energy
Common use cases
- E = hc / λ. A 550 nm green photon is about 2.25 eV. X-rays are picometers and keV. The page uses the SI values of h and c, vacuum, one photon — not a laser pulse energy.
- Sanity-check with this case: 550 nm → ~2.25 eV. 1 nm X-ray-ish → 1.24 keV.
- The relationship is: E (J) = 6.62607015×10⁻³⁴ × 2.99792458×10⁸ / λ(m). Divide by 1.602e-19 for eV.
Localized examples
- Unit Converters: the example on this page uses the same formula as the widget.
What you get
- Fields: Wavelength (nm)
- E (J) = 6.62607015×10⁻³⁴ × 2.99792458×10⁸ / λ(m). Divide by 1.602e-19 for eV.
- Example on the page: 550 nm → ~2.25 eV. 1 nm X-ray-ish → 1.24 keV.
How to Convert Wavelength to Photon Energy Step-by-Step
- 1Enter Wavelength (nm). Use the values you have, not a catalog average, unless that is all you know.
- 2E (J) = 6.62607015×10⁻³⁴ × 2.99792458×10⁸ / λ(m). Divide by 1.602e-19 for eV.
- 3Worked case: 550 nm → ~2.25 eV. 1 nm X-ray-ish → 1.24 keV.
- 4Check which dictionary the other person is using — US or UK, decimal or 1,024 — then trust the number.
Governing formula
E (J) = 6.62607015×10⁻³⁴ × 2.99792458×10⁸ / λ(m). Divide by 1.602e-19 for eV.
550 nm → ~2.25 eV. 1 nm X-ray-ish → 1.24 keV.
Example: set Wavelength (nm) = 550, then read the result.
Variable definitions
- value
Wavelength (nm)
The “Wavelength (nm)” field. Default 550; typical range 0.01–1000000.
- The conversion (E (J) = 6.62607015×10⁻³⁴ × 2.99792458×10⁸ / λ(m). Divide by 1.602e-19 for eV.) does not pick US vs UK gallons, SI vs binary megabytes, or Mach at altitude for you. Read the footnote on the page.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
Multiply eV by 96.485 for kJ/mol of photons.
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- Celsius Heat Units to JoulesA Celsius heat unit is the heat to raise 1 pound of water by 1 °C — about 1,899 J. Old HVAC and process papers use CHU. If you expected BTU, you are on the Fahrenheit twin (1 lb × 1 °F). Do not mix them in a load calc.
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- Micrometers to NanometersBacteria, coatings, and chip features sit in micrometers. Light wavelengths and process nodes sit in nanometers. Multiply µm by 1,000. A “5 µm” particle is 5,000 nm — not 5 nm.
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4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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