# Spectral radiance unit conversion [closed]

I have spectral radiance data in SRUs (spectral radiance units), as a function of wavelength: $$a = \mu W cm^{-2} sr^{-1} nm^{-1}$$

However, I am working with software which requires my data in the form: $$b=mWcm^{-2}sr^{-1}\mu m^{-1}$$

Are these two units are equivalent?

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## closed as too localized by Emilio Pisanty, Waffle's Crazy Peanut, Sklivvz♦, Manishearth♦Jan 15 '13 at 6:30

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Well, $1\textrm{ mW}=1000\, \mu \textrm{W}$ and $1\,\mu\textrm{m}=1000\textrm{ nm}$, so that $$1\textrm{ mW}\,\textrm{cm}^{-2}\textrm{sr}^{-1}\mu\textrm{m}^{-1}= 1000\textrm{ mW}\,\textrm{cm}^{-2}\textrm{sr}^{-1}\left(1000\textrm{ nm}\right)^{-1}= 1 \,\mu\textrm{W}\,\textrm{cm}^{-2}\textrm{sr}^{-1}\textrm{nm}^{-1}$$ and both units are exactly equivalent.