Flag Dimensions
Flag proportions are generally described as a ratio of height to width (or length) of the flag. A 1:2 flag is 1 unit tall for every 2 units wide. Many countries have a precise specification for the proportions of their flag. These run the gauntlet, from square (Switzerland) to very long (Montenegro).
When many flags are displayed together, it is common to present them in a uniform size. When a flag is displayed alone, it is generally preferable to show it in its official proportions.
For a list of countries by proportions of national flags click here
For flags of the world categorised by their ratios click here
For a glossary of vexillology (the study of flags) click here
Flying a flag at half-mast click here