 "Herefordopterus" is classified in Hughmilleriidae, a pterygotioid family that is differentiated by their streamlined bodies, the enlargement of its medium-sized chelicerae and the presence of paired spines on the walking appendages.It was distinguished for combining characteristics of "Hughmilleria" with those of the derived pterygotioids, showing a more advanced morphology than that of "Hughmilleria".With the biggest specimen measuring 12 centimetres (5 inches) in length, "Herefordopterus" is considered a eurypterid of small size.