A widely used metric for the analysis of swarm coordination algorithms is based upon the distance between agents. This paper examines this metric and introduces an entirely new metric based upon the magnitude of the cohesion and repulsion vectors between agents. In comparing and contrasting the two metrics, we find that the cohesion/repulsion metric offers a number of advantages over the distance metric. In particular, the cohesion/repulsion metric allows the identification of the essential characteristic of a swarm as ‘expanding’, ‘stable’, or ‘contracting’. This is not possible with the distance metric. Practical swarming applications where the new metric is useful include area filling and reconnaissance.