According to Polybius1, during the period of the Republic, Roman legionaries in formation had about 180 cm of space (both depth and width), which was 3.24 square meters. A more reliable source of information – Vegetius2 – is to indicate a width of 90 cm and a depth of 200 cm, i.e. 1.8 square meters.
Polybius gives his data in the section on the comparison of the combat value of the legion to the phalanx. He compares here the exceptionally large space of the legionaries against the tight array of phalanxes (each was 90 cm wide and deep).
According to Polybius, the Roman legionary was supposed to have enough space to be free to use the sword to strike and throw a javelin, as well as to maintain a sense of security that his companions were nearby.
As Adrian Goldsworthy points out, Roman soldiers, if we believe ancient records, had much more space in the formation for, for example, British troops during the Napoleonic Wars – soldiers at the beginning of the 19th century could only count at about 50-80 cm deep.
The Republican standard maniple, consisting of 120 soldiers, was usually 6 to 8 ranks wide. With 6 rows of depth, the maniple consisted of 20 people in the line, which for the given width of 90 cm for a legionary gave a total of 18 meters of the maniple’s combat line. The depth at 200 cm per soldier is 12 meters deep for the 6th private unit. According to Adrian Goldsworthy, a typical legion would then have the front line, including the intervals between manipulations, 365 meters. In turn, a consular army consisting of two Roman legions and two alae allies would have a front of almost 1.5 km.