Australia

What the source says

Checked against the constituting document

The Australian National Flag is a blue flag [...] having: (a) the Union Jack occupying the upper quarter next the staff; (b) a large white star (representing the 6 States of Australia and the Territories) in the centre of the lower quarter next the staff [...]; and (c) 5 white stars (representing the Southern Cross) in the half of the flag further from the staff. Table A — Commonwealth Star: Outer Diameter three-tenths of width of flag; Inner Diameter four-ninths of outer diameter; Number of Points: Seven.

[1] Flags Act 1953 (Cth), Schedule 1, clauses 1 and 1A and Table A (Federal Register of Legislation, Australian Government), read on 2026-07-17. Backs which colors the flag has, the proportions and the description of the design on this page.

Checked means compared against the quoted text, not read by a person. What the marks mean.

Colors and meaning

Navy blue[1] #00008B
The historic ties to Britain via the Union Jack canton
White[1] #FFFFFF
The Commonwealth Star and the Southern Cross stars

What the law specifies[1]

The Flags Act declares the flag to be a blue flag with the Union Jack in the upper quarter next the staff, a large white star of seven points in the centre of the lower quarter — which the Act itself says represents the six states of Australia and the territories — and five white stars in the fly representing the Southern Cross. The star's outer diameter is three-tenths of the flag's width.

Symbolism and history

The design originated in a public competition held at federation in 1901, though the flag was only established in law by the Flags Act half a century later.

Most similar flags

The 6 closest of the 194 other national flags, ranked by a similarity index computed from the flag images themselves. The number is that index, 0–100 — not a claim that the two flags are “X% identical”.

Computed at build time: each flag is rasterised to 64x48, and the score is 0.55 × colour overlap + 0.45 × structure. A different weighting would rank these differently. How the index works.

Sources

[1] Verified against Flags Act 1953 (Cth), Schedule 1, clauses 1 and 1A and Table A (Federal Register of Legislation, Australian Government) on 2026-07-17. Backs which colors the flag has, the proportions and the description of the design on this page. The passage it was checked against is quoted at the top of this entry.

Further reading: Flag of Australia on Wikipedia