Planck Law Spectrum Calculator

Model blackbody emission with Planck’s radiation law precisely. Choose wavelength limits, step size, and units. See peak shifts as temperature rises across spectra clearly.

Inputs

Mode

Switch between wavelength-based and frequency-based forms.

Temperature (K)

Typical examples: 300 K, 1000 K, 5800 K.

X-axis unit

Choose a practical unit for your range values.

Range start

Range end

Step size

Keep total points under 3000 for fast export.

Output unit

Select a unit commonly used in optics and thermal analysis.

Note: This tool computes spectral radiance for an ideal blackbody. For real materials, emissivity and geometry can modify results.

Example Data Table

Temperature (K)	Wavelength (nm)	Spectral radiance (W·sr⁻¹·m⁻²·nm⁻¹)	Notes
300	10000	≈ 9.9e-3	Thermal infrared dominates at room temperature.
1000	3000	≈ 1.1e+2	Peak moves toward near-infrared with heating.
5800	500	≈ 2.6e+7	Visible band becomes strong for solar-like temperatures.

Values are indicative and depend on exact constants and units.

Formula Used

Planck’s law describes the spectral radiance of an ideal blackbody at temperature T. This calculator supports both wavelength and frequency forms.

Wavelength form: Bλ(λ,T) = (2hc²/λ⁵) · 1/(exp(hc/(λkT)) − 1)
Frequency form: Bν(ν,T) = (2hν³/c²) · 1/(exp(hν/(kT)) − 1)
Peak wavelength estimate (Wien): λmax = b/T, with b = 2.897771955×10⁻³ m·K

Constants used: Planck constant h, speed of light c, and Boltzmann constant k in SI units.

How to Use This Calculator

Select Mode: wavelength spectrum (Bλ) or frequency spectrum (Bν).
Enter the temperature in Kelvin.
Choose an X-axis unit and provide start, end, and step size.
Select an output unit that matches your reporting needs.
Click Calculate to generate the spectrum preview.
Use Download CSV or Download PDF to export full data.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.