— Safety is a critical success factor for consumer acceptance of domestic robotic products. Some researchers have adopted the Head Injury Criterion (HIC) as absolute safety norm. However, this norm covers only part of the safety risk. In many cases skin damage (e.g. cuts, wounds, etc) can be a more serious risk. This article shows how to work towards a novel absolute safety measure for evaluating the shape and material choices of a robotic design w.r.t. skin damage. The proposed safety norm evaluates the situation of an unintended uncontrolled collision of a robotic part against a human. Maximum curvatures of the exterior robotic shape are approximated as a sphere in contact with the human skin (locally approximated as a flat surface). This local spheric approximation of the impact contact is used to predict maximum tensile stress during impact of the robotic part on the human. Robotic designs that include points for which the tensile strength of the skin is exceeded will cause at l...