What colors are on the Australian flag?

The Australian flag uses three colours: blue for the background and the main canton, red and white inside the Union Jack in the upper-left corner, and white for the Commonwealth Star and the five stars of the Southern Cross. There is no green or gold on the national flag, even though green and gold are Australia's official national sporting colours.

The blue field is the historical Blue Ensign of the British merchant navy, used for non-military British government vessels and adopted across the British Empire for colonial flags. White and red appear inside the Union Jack as the crosses of Saint George (red on white, for England), Saint Andrew (white diagonal on blue, for Scotland), and Saint Patrick (red diagonal on white, for Ireland). The combination dates from the Acts of Union of 1801, when Ireland was joined to Great Britain.

From 1901 until 1953, both a Blue Ensign version and a Red Ensign version of the flag were in common use. The Red Ensign flew over civilian shipping and was widely flown by ordinary Australians on land as well, while the Blue Ensign was reserved for government buildings and naval vessels. The Flags Act 1953 settled the question by making the Blue Ensign the exclusive national flag, with the Red Ensign retained only for use at sea by Australian merchant ships.

The exact shade of blue specified for the flag is Pantone 280 C, the same deep navy blue used on the British and New Zealand ensigns. Red and white are also specified as Pantone 185 C and pure white. These colour standards ensure flags produced by different manufacturers all match when flown side by side at official events.