The flag of Eritrea has an aspect ratio of 1:2. It is divided into three main parts: a red isosceles triangle with its base along the hoist side and its apex at the center of the flag, and two equilateral triangles on either side of the red triangle.

The red triangle has RGB color code (186, 12, 47) or hexadecimal #BA0C2F. The top equilateral triangle is green with RGB color code (0, 166, 81) or hexadecimal #00A651. The bottom equilateral triangle is blue with RGB color code (0, 38, 100) or hexadecimal #002664. Inside the red triangle, there is a yellow 12-pointed star with an RGB color code (252, 209, 22) or hexadecimal #FCD116.

To construct the flag:

1. Draw a rectangle with dimensions 1x2.
2. Divide it into two equal halves by drawing a vertical line at the halfway point.
3. Draw an isosceles triangle that starts from the top-left corner and ends at the bottom of the halfway vertical line, with its apex at the midpoint of the fly edge of the flag (1:1). Fill it with red (#BA0C2F).
4. Draw two equilateral triangles adjacent to the red triangle, with one on top (green: #00A651) and one below (blue: #002664).
5. Place a 12-pointed star in the red triangle centered along the halfway vertical line. Each ray of the star should have an angle of 30 degrees between them, making a full circle of 360 degrees. Fill it with yellow (#FCD116).