The flag of Saint Martin doesn't have an official design, as the island is divided into two territories: the French Collectivity of Saint Martin and the Dutch Sint Maarten. Each territory has its own flag.

The French Collectivity of Saint Martin flag features a light blue field (color code #74ACDF) with the coat of arms in the center. The aspect ratio is 2:3.

The flag of Sint Maarten consists of two horizontal bands: the upper one is red (color code #B40C0C), and the lower one is blue (color code #002A8F). A white equilateral triangle (color code #FFFFFF) is located at the hoist side, charged with the Sint Maarten coat of arms. The aspect ratio is 2:3.

Since there isn't a unified flag for Saint Martin, it's not possible to provide specific geometric properties and measurements for a single flag.