The flag of Guam has a dark blue background with a narrow red border on all sides. In the center of the flag, there is a large circle in gold depicting a proa sailing in Agana Bay near Hagåtña, with a light blue sky and waves in white. Above the proa, there is a red banner with the word "GUAM" in bold capital letters.

The aspect ratio of the flag is 22:41, and the circle in the center has a diameter of 3/8 the height of the flag. The geometric properties are that the center of the circle is located at a point 7/20 of the distance from the hoist to the fly, and the center of the banner is located at a point 10/27 of the distance from the hoist to the fly.

The color codes for the flag are:

• Dark blue: Pantone 286 C / RGB 0, 35, 149 / CMYK 100, 90, 13, 2
• Red: Pantone 186 C / RGB 206, 17, 38 / CMYK 0, 100, 81, 1
• Gold: Pantone 116 C / RGB 255, 204, 0 / CMYK 0, 16, 100, 0
• Light blue: Pantone 298 C / RGB 102, 204, 255 / CMYK 59, 15, 0, 0
• White: RGB 255, 255, 255 / CMYK 0, 0, 0, 0