The flag of Tuvalu has a sky blue background with the Union Jack in the upper hoist-side quadrant and nine yellow, five-pointed stars forming a slightly tilted ellipsis in the lower fly side. The aspect ratio of the flag is 1:2.

Colors:

• Sky Blue: Pantone 299C, HEX #00B5E2, RGB (0,181,226)
• Union Jack Red: Pantone 186C, HEX #C8102E, RGB (200,16,46)
• Union Jack Blue: Pantone 280C, HEX #012169, RGB (1,33,105)
• Yellow Stars: Pantone 116C, HEX #FFCD00, RGB (255,205,0)

Geometric properties and measurements:

• Union Jack occupies the top left quarter of the flag.
• Each star has five points, positioned in an elliptical shape that is slightly tilted to the right.
• The stars represent the nine islands of Tuvalu, and their size is roughly proportional to each island's population.

Please note that specific measurements for the stars' positions and sizes are not provided here.