The flag of Cocos (Keeling) Islands has an aspect ratio of 1:2. It consists of three horizontal stripes and a canton in the upper hoist-side corner. The top stripe is green (#007A3D), the middle stripe is white (#FFFFFF), and the bottom stripe is blue (#00247D). The canton is also green (#007A3D) and features a yellow crescent moon (#FCD116) and a yellow circle containing a twelve-pointed star (#FCD116).

The width of each stripe is equal, with each taking up one-third of the flag's height. The canton spans half the flag's length and two-thirds of its height.

Exact measurements and geometric properties depend on the specific size of the flag being produced.