Wavelength Spectral Irradiance Converter
Convert wavelength-based spectral irradiance between per-nanometer, per-micrometer and area 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
Convert power, area and the wavelength interval denominator independently, keeping the same wavelength basis.
Eλ in W/(m²·m) = value × power factor / (area factor × wavelength-interval factor)
Worked example
1 W/(m²·nm) is 1000 W/(m²·µm). One µW/(cm²·nm) is 0.01 W/(m²·nm).
Assumptions and input details
This is a spectral density per wavelength interval at the same wavelength. Per-frequency density in W/(m²·Hz) needs a wavelength-dependent Jacobian and is intentionally not a unit choice here. The tool does not integrate a spectrum, change spectral resolution, estimate sunlight or convert to photon flux.
References: BIPM: SI quantities and prefixes · NIST: spectral irradiance unit conventions
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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