Flag Ratios, Proportions and Sizes
In Spain most flags follow the traditional 2:3 ratio of the national flag. Exceptions are to be found with the Madrid Community which has a 7:11 flag, Castile and Leon a 76:99 flag, Castile-La Mancha a 1:2 flag and the Basque Country a 14:25 flag. Madrid City has both 2:3 and 3:5 official versions of the flag.
Ensigns are 2:3. Rank flags as well as the king's and prince's standards are 1:1. Military Colours, cavalry and armoured units' guidons are 1:1.
Royal Decree 2964/1981 of December 18th 1981. Coat-of-arms and its placement on the flag.
Article 3. The coat-of-arms of Spain shall have a height of 2/5ths the width
of the flag and shall appear on both sides of it on the middle [vertically]
of the yellow stripe.
When the flag of Spain has the usual proportions, a length of three halves its width, the [vertical] axis of the coat-of-arms shall be placed at a distance from the hoist of half the flag's width.
If the length were smaller than usual or the flag were square the coat-of-arms shall be placed on the centre of the flag.
The Flag of Spain