United Kingdom
Authority: Royal Proclamation of 1 January 1801
The Union Jack has an official aspect ratio of 1:2 (a separate 3:5 version is used for some government land flying). It combines the red cross of St George (England), the white saltire of St Andrew (Scotland) from 1606, and the red saltire of St Patrick (Ireland) added in 1801.
| Parameter / Specification | Standard Value | Unit |
|---|---|---|
| Hoist to Fly Ratio | 1 : 2 | - |
| Alternate Land Flag Ratio | 3 : 5 | - |
| Current Design Adopted | 1 January 1801 | - |
History & Origin
The Union Jack was built in two stages, each marking a political union. When James VI of Scotland inherited the English throne in 1603, joining the two crowns, a royal decree of 12 April 1606 ordered that "the Red Crosse, commonly called St George's Crosse, and the White Crosse, commonly called St Andrew's Crosse" be joined on a blue field -- the red cross of England's patron saint laid over the white diagonal saltire of Scotland's.
The design reached its current form on 1 January 1801, following the Act of Union with Ireland. A red saltire representing St Patrick's Cross was added and counterchanged with St Andrew's white saltire, producing the diagonal red-and-white pattern still flown today; the counterchange is deliberately offset to reflect that Scotland's union with England came first. Wales has no separate emblem in the flag, since it was already treated as part of the Kingdom of England when the first Union Flag was designed in 1606.