Flag of Nepal

Nepal's flag is made of two stacked triangular pennants, which makes it the only national flag that is not a rectangle or square. A crimson field carries a white moon and sun.

Switzerland and the Vatican use square flags, but those still have four sides.

Context

Nepal's flag is made of two stacked triangular pennants, a shape that goes back centuries to banners flown by rival ruling families, and it was formally standardised in the country's 1962 constitution, which gave a geometric construction for drawing it. Because the shape is defined by a set of steps, the flag is sometimes described as unusual among national symbols.

The crimson colour is associated with Nepal's national flower, the rhododendron, and the blue border is a symbol of peace. The sun and moon are commonly said to express the hope that the nation will last as long as these bodies, though interpretations of the symbols vary among sources.

Britannica states that Nepal is the only country in the modern world without a rectangular national flag. The claim is about national flags; some subnational, ceremonial and historical flags are non-rectangular. Ohio's state flag, a swallowtail burgee, is an example of a non-rectangular flag outside the national level.

The construction instructions in the constitution specify the proportions of the pennants and the shapes of the sun and moon emblems, so reproductions are expected to follow a fixed geometric method.