This dataset contains the raw ash particle size measurements and derived shape parameters used in Figures 8a and 8b in Liu et al., (2015). All size measurements were made on backscattered electron SEM images using ImageJ image analysis software. The ImageJ macro used to make these measurements is also supplied within this repository folder. Size measurements for each particle are in units of pixels. This dataset forms part of the supplementary material for the publication Liu, E.J., Cashman, K.V., Rust, A.C, (2015), ‘Optimising shape analysis to quantify volcanic ash morphology’, GeoResJ, 8.