The flag of the British Indian Ocean Territory (BIOT) consists of a blue ensign with the Union Jack in the upper hoist-side quadrant and the BIOT emblem on the fly side. The color codes for the flag are as follows:

• Blue (Pantone 280 C): #012169 (background)
• Red (Pantone 186 C): #C8102E (Union Jack)
• White: #FFFFFF (Union Jack)

The aspect ratio of the flag is 1:2, meaning its width is half of its length. The emblem consists of a wavy white diagonal band with a palm tree and St. Edward's crown above it. The band starts at the lower hoist-side and ends at the upper fly-side. The exact dimensions and geometric properties of the emblem or the Union Jack relative to the overall flag size are not standardized.

Unfortunately, I can't provide any more detailed measurements without including a description of the flag's symbolism or more specific information about the design features.