Function metrics make early design evaluation possible. A simple definition of function as a pair of behavior expressions that map the utilized part of a component behavior to an intended part of a device behavior enables formal definition of several useful metrics for engineered devices such as sharing, overload, modularity, and criticality. These function metrics can be used to evaluate properties of a given configuration of components in a device as well as to compare alternative configurations of devices for the same design intents. A program called Teleometrics has been implemented that models function representations of devices as graphs and generates function metrics. Four patented accelerometers used for automotive crash sensing are modeled, evaluated, and compared using Teleometrics.