Almost every national flag is a rectangle, somewhere between a 1:2 and a 3:5 ratio, close enough to each other that most people never think about the shape at all. A small handful of countries break from that entirely, either in outline or in proportion, and each one has a distinct reason for it.
Nepal
The only non-rectangular national flag in the world. Two stacked triangular pennants rather than a single rectangle, representing the Himalayas and Nepal’s two major religious traditions, with a moon in the upper triangle and a sun in the lower one. The shape is fixed by the constitution down to the geometry, drawn with a compass and straightedge rather than free-hand proportions.
Switzerland
A perfect square, one of only two square national flags in the world alongside Vatican City’s. The proportions were formally set in 1889, and the shape has become closely tied to Swiss identity, so much so that the Red Cross symbol is literally the Swiss flag with its colors inverted.
Qatar
The most stretched-out flag on earth, at a ratio of roughly 1:2.5, more than twice as long as it is tall. The serrated edge separating its white and maroon sections is also unusual, nine white triangular points cutting into the maroon field, more commonly associated with Bahrain’s flag than Qatar’s own neighbors.