Australia was designed with eight 8-inch guns in four twin turrets ('A' and 'B' forward, 'X' and 'Y' aft) as primary armament, with 150 shells per gun.
Secondary armament consisted of four 4-inch guns in four single mounts, with 200 shells per gun, and four 2-pounder pom-poms for anti-aircraft defence, with 1,000 rounds each.
A mixture of .303-inch machine guns were carried for close defence work: initially this consisted of four Vickers machine guns and twelve Lewis machine guns, although four Lewis guns were later removed.
Two sets of quadruple 21-inch torpedo tubes were fitted.
Four 3-pounder quick-firing Hotchkiss guns were used as saluting guns.
During her 1939 modernisation, the four single 4-inch guns were replaced by four twin Mark XVI guns.
The torpedo tubes were removed in 1942, and the 8-inch 'X' turret was taken off in 1945.

The close-range anti-aircraft armament of the ship fluctuated during her career.
During the mid-1930s, two quadruple .5-inch machine gun mounts were installed to supplement the .303-inch weapons.
These were replaced in late 1943 by seven single 20mm Oerlikons.
By early 1944, all seven Oerlikons had been upgraded to double mountings.
These were in turn replaced by eight single 40 mm Bofors guns in 1945.

Australia was designed to carry a single amphibious aircraft: a Supermarine Seagull III aircraft, which was replaced in 1936 by a Supermarine Walrus.
Both aircraft were operated by the Royal Australian Air Force's Fleet Co-operation Unit; initially by No.
101 Flight RAAF, which was expanded in 1936 to form No.
5 Squadron RAAF, then renumbered in 1939 to No.
9 Squadron RAAF.
As the aircraft catapult was not installed until September 1935, the Seagull was initially lowered into the water by the ship's recovery crane to launch under its own power.
The catapult and Walrus were removed in October 1944.

Armour aboard Australia was initially limited to an armour deck over the machinery spaces and magazines, ranging from 1.5 to 3 inches (38 to 76 mm) in thickness.
Armour plate was also fitted to the turrets (up to 2 inches (51 mm) thick) and the conning tower (3 inches (76 mm) thick).
Anti-torpedo bulges were also fitted.
During 1938 and 1939, belt armour up to 4.5 inches (110 mm) thick was fitted along the waterline to provide additional protection to the propulsion machinery.
Australia was designed with eight 8-inch guns in four twin turrets ('A' and 'B' forward, 'X' and 'Y' aft) as primary armament, with 150 shells per gun. Secondary armament consisted of four 4-inch guns in four single mounts, with 200 shells per gun, and four 2-pounder pom-poms for anti-aircraft defence, with 1,000 rounds each. A mixture of .303-inch machine guns were carried for close defence work: initially this consisted of four Vickers machine guns and twelve Lewis machine guns, although four Lewis guns were later removed. Two sets of quadruple 21-inch torpedo tubes were fitted. Four 3-pounder quick-firing Hotchkiss guns were used as saluting guns. During her 1939 modernisation, the four single 4-inch guns were replaced by four twin Mark XVI guns. The torpedo tubes were removed in 1942, and the 8-inch 'X' turret was taken off in 1945.
The close-range anti-aircraft armament of the ship fluctuated during her career. During the mid-1930s, two quadruple .5-inch machine gun mounts were installed to supplement the .303-inch weapons. These were replaced in late 1943 by seven single 20mm Oerlikons. By early 1944, all seven Oerlikons had been upgraded to double mountings. These were in turn replaced by eight single 40 mm Bofors guns in 1945.
Australia was designed to carry a single amphibious aircraft: a Supermarine Seagull III aircraft, which was replaced in 1936 by a Supermarine Walrus. Both aircraft were operated by the Royal Australian Air Force's Fleet Co-operation Unit; initially by No. 101 Flight RAAF, which was expanded in 1936 to form No. 5 Squadron RAAF, then renumbered in 1939 to No. 9 Squadron RAAF. As the aircraft catapult was not installed until September 1935, the Seagull was initially lowered into the water by the ship's recovery crane to launch under its own power. The catapult and Walrus were removed in October 1944.
Armour aboard Australia was initially limited to an armour deck over the machinery spaces and magazines, ranging from 1.5 to 3 inches (38 to 76 mm) in thickness. Armour plate was also fitted to the turrets (up to 2 inches (51 mm) thick) and the conning tower (3 inches (76 mm) thick). Anti-torpedo bulges were also fitted. During 1938 and 1939, belt armour up to 4.5 inches (110 mm) thick was fitted along the waterline to provide additional protection to the propulsion machinery.
HMAS Australia (D84)