A set of thirty Junge-type size distribution curves are used to represent the average features of the multimodal size spectra of Sahara dust particles, as obtained from samples deposited by rain. For these size distributions, characterized by values of Junge exponent ranging from 1.5 to 4.4 within the 0.1–3 μm radius interval, accurate calculations of the Mie extinction coefficients per unit air volume and unit particle mass are obtained at twelve wavelengths between 0.40 and 1.03 μm. The examination of Sahara dust optical thickness measurements in terms of these extinction coefficients shows that Junge-type extinction models can give reliable estimates of the vertical mass loading of Sahara dust particles, which are in close accordance with those given by extinction models based on trimodal size distributions.