In the United States Army, there are between 16 and 40 soldiers in a platoon, notes the U.S. Army's website. Other countries' armies have different numbers, such as Australia's army's 24-soldier platoons, and the units may be called by different names outside the U.S.
Furthermore, a U.S. Army platoon is made up of three or four squads, which are the lowest unit group, and each squad has between four and 10 soldiers. Above the platoon in the U.S. Army's organizational unit chart are the company (made up of three or four platoons), the battalion (made up of three to five companies), the brigade (made up of at least 3 battalions), the division (made up of at least three brigades), the corps (made of between two to five divisions) and the field army on top. Although these are the most common units, there are additional ones, notes the U.S. Army website.