PyMieScatt (Python Mie Scattering) calculates relevant parameters including absorption, scattering, extinction, asymmetry, and backscatter. The package also contains single-line functions to calculate optical coefficients (in Mm-1) of ensembles of particles in lognormal (with single or multiple modes) or custom size distributions. The inverse calculations retrieve the complex refractive index from laboratory measurements of scattering and absorption (or backscatter), useful for studying atmospheric organic aerosol of unknown composition.