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Planck Spectral Radiance Calculator

B_λ(T) at a wavelength λ for a blackbody at T.

Compute the spectral radiance B_λ(T) of a blackbody at wavelength λ and temperature T using Planck's law: B_λ = 2hc² / λ⁵ · 1 / (exp(hc / λkT) − 1).

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

nm
K

Results

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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

B_λ(T) = 2hc² / λ⁵ · 1 / (exp(hc / λkT) − 1)

In depth

Compute the spectral radiance B_λ(T) of a blackbody at wavelength λ and temperature T using Planck's law: B_λ = 2hc² / λ⁵ · 1 / (exp(hc / λkT) − 1).