Why Are Most Flags Rectangular?

Most flags are long rectangles because it is easy to fold and hang them. Imagine a towel; it has four corners and two sides that look the same when flipped. Triangular flags have uneven sides which can get tangled in the wind. The rectangle is simple, strong, and works for everyone.

Triangular flags, called pennants, were popular long ago because they cut through the air better on ships. However, as people started using flags on land, the triangle became awkward to attach to poles. A rectangle fits neatly into a sleeve or is sewn directly onto a pole.

We like things that look balanced. Rectangles follow a rule called aspect ratio. Most flag makers use 2:3 or 1:2 ratios. This means the flag is usually twice as wide as it is tall, or half again as wide. It looks friendly and familiar to our eyes.

Long ago, kings wore long robes that looked like rectangular flags. When we started making national flags for countries, we copied those royal styles. Countries in Europe used rectangles because their nobles did too. Now, almost every country copies the rectangle because it is what everyone else uses.