The flag of Montserrat has a blue field (Pantone 286C) with the Union Jack in the canton and the Montserrat coat of arms centered on the right half. The aspect ratio of the flag is 1:2.

The Union Jack consists of red (Pantone 186C) and white crosses over a blue background. The Montserrat coat of arms features a shield with a green (Pantone 355C) base, divided by a diagonal white stripe with a woman in green holding a golden harp, and a black (Pantone Black C) top portion with two red (Pantone 186C) sugarloaf-shaped structures.

Unfortunately, precise geometric properties and measurements are not readily available for the flag's design elements.