The flag of Guernsey consists of a white background with a red cross that extends to the edge of the flag. The cross has a width of 1/3 of the flag's height, and each arm of the cross has a width of 1/6 of the flag's height. The color codes for the flag are:

• White: #FFFFFF
• Red: #ED1C24

The aspect ratio of the flag is 2:3. The flag has no official geometric properties or measurements other than its aspect ratio.