  The varied landscape of robotic hand designs makes it difficult to set a
standard for how to measure hand size and to communicate the size of objects it
can grasp. Defining consistent workspace measurements would greatly assist
scientific communication in robotic grasping research because it would allow
researchers to 1) quantitatively communicate an object's relative size to a
hand's and 2) approximate a functional subspace of a hand's kinematic workspace
in a human-readable way. The goal of this paper is to specify a measurement
procedure that quantitatively captures a hand's workspace size for both a
precision and power grasp. This measurement procedure uses a {\em functional}
approach -- based on a generic grasping scenario of a hypothetical object -- in
order to make the procedure as generalizable and repeatable as possible,
regardless of the actual hand design. This functional approach lets the
measurer choose the exact finger configurations and contact points that satisfy
the generic grasping scenario, while ensuring that the measurements are {\em
functionally} comparable. We demonstrate these functional measurements on seven
hand configurations. Additional hand measurements and instructions are provided
in a GitHub Repository.
