The flag of Puerto Rico has an aspect ratio of 2:3. It consists of five horizontal stripes: three red (#FF0000) and two white (#FFFFFF), alternating with the first and last stripe being red. On the left side, there's a blue isosceles triangle (#00247D) with its base at the hoist and its apex touching the middle of the fly end. Within the triangle, there is a white five-pointed star.

Geometric properties:

1. The length of each stripe is equal and spans the entire width of the flag.
2. The triangle's height is equal to the flag's height, and its base is one-third of the flag's width.
3. The white star is centered within the triangle and oriented such that one point is pointing upwards.

There are no specific measurements for the flag, as it can be scaled according to use. However, the geometric proportions must remain consistent.