Construction Details of the Australian Flag

Last modified: 2023-07-03 by
Keywords: australia | southern cross | stars: 7 points | construction sheet |
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• Construction Details
• Comparison with New Zealand's flag

• Australia

The Australian flag is defined by the Flags Act 1953, which can be found here. The construction details are defined in the schedule to the act.
Jonathan Dixon, 5 February 2003

All the stars have an inner diameter (circle on which the inner corners rest) of 4/9 the outer diameter (circle of outer corners), even the 5-point star. The positions of the stars are as follows:

• commonwealth star - centred in lower hoist,
• alpha - straight below centre fly 1/6 up from bottom edge,
• beta - 1/4 of the way left and 1/16 up from the centre fly,
• gamma - straight above centre fly 1/6 down from top edge,
• delta - 2/9 of the way right and 31/240 up from the centre fly,
• epsilon - 1/10 of the way right and 1/24 down from the centre fly.

The outer radius of the 7-pointed stars in the Southern Cross should be 1/14 the width of the fly (the "height" of the flag). For the 5-pointed star it should be 1/24. The Commonwealth star should be 3/20. In each case, the inner radius should be 4/9 of the outer radius.
Jonathan Dixon, 3 February 2003

A good template of the Australian flag can be found at http://www.itsanhonour.gov.au/images/flag_template.jpg. Below is a different representation:
by Mello Luchtenberg and Jonathan Dixon, 3 February 2003

The Australian and New Zealand flags are both blue with the Union Jack in the canton and the southern cross in the fly. The federation star in the lower hoist is unique to the Australian flag. When comparing the representations of the southern cross on the flags of Australia and New Zealand, we find that

• The cross is slightly "taller" on the Australian flag (the distance between Alpha and Gamma Crucis is 2/3 of the hoist, rather than 3/5).
• In the NZ case, the positioning of Beta and Delta Crucis is described in terms of a line which forms an angle of 82º with the vertical, which is the same as the angle formed by the line between Beta and Delta in the Australian flag, to an accuracy of 1 degree.
• The abovementioned line is slightly higher on the NZ cross than on the Australian - splitting the vertical line between Alpha and Gamma 2:1 compared to roughly 11:6 (actually 1759:961).
• On the NZ flag, the line between Beta and Gamma is cut by the vertical line in the ratio 7:6, compared with 9:8 for the Australian flag.
• The overall horizontal distance between Beta and Gamma is greater on the Australian flag, 17/36 (roughly 0.47) of the hoist length, compared with roughly 0.43 of the hiost length for NZ. This is entirely due to the NZ cross being smaller overall, as the width of the cross is 17/24 (roughly 70.8%) of the height in the Australian case, compared with roughly 71.5% for NZ.

As a summary, the Southern Cross on the Australian flag is larger than the NZ one, and has a slightly thinner shape. The intersection of the "arms" forms the same angle in both flags, but is both slightly lower and slightly more horizontally central than the intersection in the NZ cross, which is more skewed towards the hoist, although these differences are fairly negligible.

Of course, the main difference between the two crosses is that the New Zealand flag has one less star, and has all the stars with 5 points and in red rather than white.
Jonathan Dixon, 12 February 2003