Contubernium (8 men) > Centuria (80 men) > Cohort (480 men) > Legio (5,000 men)

Legio (Legion) - (10 Cohorts = 5,000 men)

Until the middle of the first century, 10 cohorts (about 5,000 men) made up a Roman Legion. This was later changed to nine cohorts of standard size (with 6 centuries at 80 men each) and one cohort, the first cohort, of double strength (5 double-strength centuries with 160 men each).

Each legion had 59 centurions, one to command each centuria of the 10 cohorts.

The commanding officer of a Roman legion was called a legate, or Legatus Legionis.

Contubernium (8 men) > Centuria (80 men) > Cohort (480 men) > Legio (5,000 men)

The Cavalry Each Legion also had a 120 man Alae (cavalry unit) called the Eques Legionis permanently attached to it possibly to be used as scouts and messengers.

Contubernium (8 men) > Centuria (80 men) > Cohort (480 men) > Legio (5,000 men)

So how many men in a Roman legion?

The Roman legion was divided into 10 cohorts:

The First Cohort had more soldiers than the other cohorts. The first cohort was made up of 800 men (5 centuries with 160 men each). The other 9 Cohorts had a total of 4,320 soldiers (6 centuries of 80 men each).

A grand total of 5,240 men not including all the officers.

Standards (signa)

Each century, cohort and legion had its own standard (flags and symbols on a long pole).
Find out more here