The Flag Institute recommends the following specification for the Union Flag (or Union Jack).
For guidance on the rules to follow when flying this flag, see UK Flag Protocol.
1. The Union Flag comprises three crosses on a royal blue background:
- a red St George’s cross
- a white St Andrew’s saltire
- a red St Patrick’s saltire
2. The proportions of the flag are 30 units wide by 50 units long
3. Each diagonal is in total six units wide, comprising white (three units), red (two units), one white (unit):
- the broader white diagonal is uppermost on the side of the flag nearest the flagpole (i.e. the hoist)
- the narrower white diagonal is uppermost on the side of the flag furthest from the flagpole (i.e. the fly)
4. The two six-unit-wide diagonals run from corner to corner:
- the centre line of each six-unit-wide diagonal intersects opposite corners of the flag
- the centre line of each six-unit-wide diagonal intersects the centre line of the other six-unit-wide diagonal in the centre of the flag
5. A red cross six units wide runs from edge to edge, centred on the flag
6. This red cross has a white fimbriation (or border) two units wide.
7. The flag should fly with the broader white diagonal on the side nearest the flagpole uppermost.
8. The recommended colours are: Pantone 280 C (royal blue); Pantone 186 C (red); no specification (white).
- the normal proportions for use on land are 3:5
- the customary proportions of ensigns for use at sea are 1:2
- the specification for the 1:2 version replaces the length of 50 with 60
- the specification for the 1:2 version replaces the angle of 30.96º degrees with 26.57º.
Union Flag Bill (2008)
The Flag Institute submitted this specification to the UK Parliament during the drafting of the Union Flag Bill (2008).
The Union Flag Bill (2008) aimed to codify longstanding custom and practice regarding the Union Flag (Union Jack).
It affirmed the Union Flag (Union Jack) as the national flag of the United Kingdom of Great Britain and Northern Ireland. It confirmed the flag’s proportions as 3:5 for use on land. It endorsed the flag’s dual names and provided a written description and diagram.
The bill was introduced under the Ten-Minute Rule on Tuesday 5 February 2008 but failed to progress beyond its first reading.