Military Unit Sizes: Squad to Corps, Battalion vs Brigade

Short answer: Military unit sizes in the U.S. Army run from a team of about four soldiers to a corps of tens of thousands. In order, the units are team, squad, platoon, company, battalion, brigade, division and corps. As a rule of thumb, three to five of each unit make up the next one. A battalion has a few hundred to 1,000 soldiers, a brigade a few thousand and a division 10,000 to 16,000. The exact numbers depend on the unit type and on which official source you use.

Last updated: October 27, 2026

Military unit sizes at a glance

Two official sources give slightly different ranges. The U.S. Army’s ranks page lists typical sizes for each echelon. The Congressional Research Service (CRS) quotes the Congressional Budget Office (CBO). Where they differ, both are shown.

Unit	Made up of	Size (army.mil)	Size (CBO via CRS)	Usually led by
Team	Individual soldiers	4	Part of a squad	Sergeant
Squad	2–3 teams	8–16	4–12	Staff sergeant (sergeant in CBO’s description)
Platoon	2–4 squads	16–44	16–50	Lieutenant, with a sergeant first class
Company	3–5 platoons	60–200	60–200	Captain, with a first sergeant
Battalion	3–5 companies	300–1,000	400–1,000	Lieutenant colonel
Brigade	3 or more battalions	1,500–3,200	4,000–4,700 (brigade combat team)	Colonel
Division	Brigades plus support	10,000–16,000	12,000–16,000	Major general
Corps	2–5 divisions	20,000–40,000	40,000–100,000	Lieutenant general
Field army	Corps plus theater support	Not listed	100,000–300,000	General

Why the ranges differ: the Army’s figures describe a basic unit, while CBO’s include the support troops attached in practice. A modern brigade combat team, for example, has its own artillery, engineers and logistics battalions, which is why CBO puts it at about 4,000 to 4,700 soldiers.

Squad, team and platoon

The team is the Army’s smallest element, usually four soldiers led by a sergeant. Two or three teams form a squad, led by a staff sergeant, and its size “is dependent on its function,” according to army.mil.

A platoon of two to four squads is “a basic combat unit capable of maneuvering” in combat. It is led by a lieutenant, usually a second lieutenant, assisted by a platoon sergeant who is a sergeant first class. CBO notes that heavy platoons operate armored vehicles such as tanks or infantry fighting vehicles.

Company, battery and troop

A company of three to five platoons is commanded by a captain, with a first sergeant as the top enlisted leader. The Army calls it a unit “that can perform a battlefield function on its own.”

The name changes by branch. Cavalry companies are called troops, while artillery and air defense companies are called batteries.

Battalion vs brigade vs division

These three are the levels most often confused.

Battalion: three to five companies, commanded by a lieutenant colonel. It is the first level that is “both tactically and administratively self-sufficient” and can fight on its own for a limited time. A cavalry battalion is called a squadron.
Brigade: three or more battalions, commanded by a colonel. It can carry out independent or semi-independent operations. Cavalry units of this size are called regiments, and Special Forces units are called groups.
Division: commanded by a major general and built for “major tactical operations” and sustained battles. CRS says an Army division usually has four brigade combat teams (two to five in all), plus aviation, artillery, engineer and logistics brigades.

So a brigade is several battalions, and a division is several brigades.

Corps and field army

A corps of two to five divisions is commanded by a lieutenant general. The Army calls it “the deployable level of command required to synchronize and sustain combat operations.” It lists three active corps headquartered in the continental United States: I, III and XVIII Corps.

Above the corps, CBO describes a field army as “the highest command level in a given theater of operations,” typically 100,000 to 300,000 personnel under a general.

Brigade combat teams: the Army’s building block

CRS calls the brigade combat team (BCT) “the Army’s basic combined-arms tactical force of about 4,000 soldiers.” The Army has 59 BCTs, 32 in the active force and 27 in the Army National Guard. They come in three types:

Type	Active	National Guard	Main vehicle
Infantry BCT	14	20	Foot, airborne or air assault
Armored BCT	11	5	M1 Abrams tanks and Bradley fighting vehicles
Stryker BCT	7	2	Eight-wheel Stryker armored vehicle

In May 2025 the Army decided to convert all infantry BCTs into Mobile Brigade Combat Teams to improve mobility and survivability, according to CRS. The armored brigades use vehicles covered in our pieces on the M1E3 Abrams and the XM30 Bradley replacement.

Other brigade-sized units

Not every brigade is a combat brigade. CRS describes several other kinds:

Functional support brigades plug into corps, divisions or theater commands and cover air defense, artillery, engineers, military police, cyber, signal, explosive ordnance disposal, medical support and aviation.
Multifunctional support brigades support BCTs directly. The five types are combat aviation, combat support, sustainment, fires and battlefield surveillance, and tactical-level task and support.
Security Force Assistance Brigades train and advise partner forces. The Army has six, five active and one in the National Guard, and CRS reports that two are to be eliminated under the Army Transformation Initiative.
Multi-Domain Task Forces are brigade-sized units built to synchronize “precision effects and precision fires in all domains” against an enemy’s anti-access defenses. The Army plans five in the active force.

How Marine Corps units compare

The Marine Corps uses similar names up to the regiment, then organizes larger forces as task forces. CRS gives these sizes:

Marine Expeditionary Unit (MEU): about 2,200 Marines under a colonel, deployed on Navy ships.
Marine Littoral Regiment: about 1,800 to 2,000 Marines and sailors.
Marine Expeditionary Brigade (MEB): 4,000 to 16,000 Marines under a brigadier general.
Marine division: three infantry regiments and an artillery regiment, about 20,000 personnel.
Marine Expeditionary Force (MEF): 46,000 to 90,000 Marines. The three active MEFs are based in California, North Carolina and Japan.

Peter’s World’s view

Analysis: Peter’s World’s assessment, based on the sources above.

The neat “three to five” rule hides how much unit sizes now depend on attached support. The gap between the Army’s 1,500-to-3,200 brigade and CBO’s 4,000-plus brigade combat team is a gap between a fighting core and a self-contained formation. When news reports say a “brigade” has been deployed, the number of troops can differ by thousands depending on which kind is meant. The Army’s current restructuring makes the label even less precise.

Frequently asked questions

What are the military unit sizes from smallest to largest?

Smallest to largest, follow the order in the table above; above corps, some armies also field a field army. Each echelon is usually built from three to five of the unit below it.

How many soldiers are in a battalion?

The Army says 300 to 1,000. CBO, quoted by CRS, says 400 to 1,000.

How many soldiers are in a brigade?

The Army lists 1,500 to 3,200 for a basic brigade. A full brigade combat team has about 4,000 to 4,700, according to CBO.

How many soldiers are in a division?

About 10,000 to 16,000 by the Army’s figure, or 12,000 to 16,000 according to CBO. A Marine division has about 20,000.

What is bigger, a regiment or a brigade?

In the U.S. Army they are the same level. Armored cavalry and Ranger units of brigade size are called regiments. In the Marine Corps, the regiment is the main unit at that level.

How many soldiers are in a platoon?

16 to 44 according to the Army, or 16 to 50 according to CBO. A lieutenant leads it with a platoon sergeant.

This article was written by Peter with AI assistance and checked against the sources linked. See our AI use disclosure.

Military Unit Sizes: Squad, Platoon, Battalion, Brigade, Division