30 mm caliber ammunition refers to one of several autocannon rounds: the 30 x 173 mm, 30 x 113 mm or 30 x 164 mm; the first two of which are used by the armed forces of NATO, the latter by former Warsaw Pact nations; these rounds are used by the armies of export customer nations as well.

Unlike the smaller 25 mm round, the 30 mm is not typically an anti-personnel weapon round. Instead, the 30 mm round is generally either an anti-material or armor-piercing round. Rounds of this size can be effective against armored vehicles and include some capability against Main Battle Tank armor as well as fortified bunkers.

The U. S. Military uses 30 mm weapons in their A-10 Thunderbolt II, AH-64 Apache, AC-130 gunships, Expeditionary Fighting Vehicle, and as a standard ship-based munition in the upcoming Mark 46 autocannon. The Armed Forces of the Russian Federation use their 30 mm weapons in a variety of vehicles, including the Su-25 attack aircraft, Mi-24 helicopter and the BTR-90 infantry fighting vehicle.

• Hughes M230 Chain Gun (US,)
• Bushmaster II (US)
• GAU-8 Avenger (US, aircraft)
• Royal Small Arms Factory ADEN cannon (UK, aircraft))
• RARDEN high velocity gun (UK, vehicle)
• GIAT 30 revolver cannon (France)
• GIAT DEFA 550 revolver cannon (France)
• GIAT M781 autocannon (France)
• Rheinmetall RMK30 recoilless cannon (Germany)
• Gryazev-Shipunov GSh-30-1(Russia, Aircraft)
• Gryazev-Shipunov GSh-30-2 (Russia, aircraft)
• Gryazev-Shipunov GSh-6-30 rotary cannon
• Oerlikon Contraves KCB (Switzerland)

30 mm ammunition generally comes in three varieties: Armor Piercing, High explosive, and Training rounds. Armor Piercing and High Explosive cartridges usually also possess incendiary characteristics.

• 5.56 mm caliber
• 7.62 mm caliber
• .50 BMG
• 12.7 x 107 mm
• 14.5 x 114 mm
• 20 mm caliber
• 25 mm caliber
• 40 mm grenade
• Caliber

• List of cartridges (weaponry), pistol and rifle

• FAS: 30 mm Ammunition
• ATK Products: M230
• ATK Products: M230LF
• French Autocannons