This paper presents a method for estimating edge length from flake dimensions. Comparison of estimated values with data from measured flake edges demonstrates the robusticity of the method. Building on the work of Braun (Braun, D.R., 2005. Examining flake production strategies: examples from the Middle Paleolithic of Southwest Asia. Lithic Technology 30, 107–125; Braun, D.R., Harris, J.W.K., 2003. Technological developments in the Oldowan of Koobi Fora: innovative techniques of artifact analysis and new interpretations of Oldowan behavior, in Mora, R., de la Torre, I. (Eds.), Oldowan: Rather More than Smashing Stones. Treballs d’ Arqueologia 9, pp. 132–144) this estimate is used to generate an edge length to mass value for complete flakes—taken to be a proxy for flaking efficiency. It is shown that this value is useful in tracking the onset, variability and decline of a well known technological phase—the Howiesons Poort of South Africa. The results suggest that the Howiesons Poort was a time in which flaking efficiency was emphasised. Furthermore, comparison of upper limits of edge to mass values for different raw materials may provide an insight into changes in raw material selection.