The flag of Brunei consists of a yellow field with two diagonal black stripes from the upper hoist-side corner to the lower fly-side corner. In the center of the flag is the national emblem in red, featuring a swallow-tailed flag above a parasol and two upraised hands.

The aspect ratio of the flag is 1:2, meaning that its width is twice its height. The geometric properties of the flag are rectangular, and its measurements are typically 105 cm x 210 cm (41.3 in x 82.7 in) for official use.

The color codes for the flag are:

• Yellow: Pantone 109C / CMYK 0, 11, 94, 0 / RGB 255, 204, 0
• Black: Pantone Black / CMYK 0, 0, 0, 100 / RGB 0, 0, 0
• Red: Pantone 186C / CMYK 0, 100, 81, 4 / RGB 206, 17, 38

The emblem in the center of the flag has a diameter of approximately one-third the height of the flag.