The flag of Puerto Rico has an aspect ratio of 2:3. It consists of five horizontal stripes, alternating between red (#FF0000) and white (#FFFFFF), with the top and bottom stripes being red. The flag also features a blue isosceles triangle (#00247D) on the left side, with its base along the hoist and its vertex at the center of the flag. Inside the triangle, there is a white five-pointed star (#FFFFFF).

The width of each stripe is equal to 1/5th of the flag's height. The triangle's height is equal to the flag's height, and its base is equal to half the flag's length. The star is equidistant from the triangle's sides and its center is located at the midpoint of the triangle's altitude. The diameter of the circumscribed circle around the star is equal to 1/8th of the flag's length.