The flag of Guinea-Bissau has an aspect ratio of 1:2. It consists of three vertical stripes and a red star within a black square on the hoist side. The colors and their respective RGB color codes are as follows:

1. Red stripe (RGB: 204, 0, 0)
2. Yellow stripe (RGB: 255, 204, 0)
3. Green stripe (RGB: 0, 102, 0)
4. Black square (RGB: 0, 0, 0)
5. Red star (RGB: 204, 0, 0)

The red and green stripes have equal widths, while the yellow stripe is twice as wide as the other two. The black square's height equals the total width of the red and green stripes. The red star is inscribed in an invisible circle centered in the black square, with the diameter being roughly 50% of the square's height.