The flag of Switzerland consists of a red square with a bold, equilateral white cross in the center. It is one of only two square sovereign-state flags, the other being the flag of the Vatican City. (The civil and state ensign, used by Swiss ships and boats, has more traditional proportions of 2:3).
Only the dimensions of the cross are formally established since 1889: "The coat of arms of the federation is, within a red field, an upright white cross, whose [four] arms of equal length are a sixth longer than their width.". The size of the cross in relation to the field is not formally established except on the naval ensign. A relation of 2:3 or 7:10 to the span of the flag is usual.
The Red Cross symbol used by the International Committee of the Red Cross is based on the Swiss flag. The Red Cross on white background was the original protection symbol declared at the 1864 Geneva Convention. It is, in terms of its color, a reversal of the Swiss national flag, a meaning which was adopted to honor Swiss native and Red Cross founder Henry Dunant.
The short-lived Free State of Icaria, proclaimed in 1912 in the Greek island of that name, used a flag similar in shape to the Swiss civil and state ensign, except for being blue rather than red.