The ability to accurately gauge the mass loss from production and resharpening of stone tools has wide-ranging implications for our understanding of early human history across the world. Recent advances in 3D laser scanning technology have facilitated unprecedented accuracy in surface area measurements of stone artefacts. This new methodology has been used to estimate flake mass, based on regression of platform surface area. This manuscript presents an analysis of ‘initial to terminal mass comparison’ using an experimental sample (n = 107) and tests empirical inferences on an archaeological assemblage (n = 400) from northern Australia. The experimental and archaeological assemblages were selected to reflect global occurrences of scrapers, convergent scrapers, and some points; making the critique of this reduction index one of global significance. The method cannot reasonably estimate the IM of all retouched flakes with intact platforms surfaces, without regression of flake subsets, reducing sample size, and greatly diminishing archaeological potential. Other reduction indices are suggested to be better suited to this task.