According to a book I found, the UK flag does in fact have an official aspect ratio, and also official ratios of stripe widths, namely: _ (technically the white part is flush with the left hand side) | | (likewise, on the right | side the red stripe is | flush with the right edge) V | 6 | 17 | 2| 6 | 2| 17 | 1| 5| __ :~8a.`~888a:::::::::::::::88......88:::::::::::::::;a8~".a888~ 3 (the white ::::~8a.`~888a::::::::::::88......88::::::::::::;a8~".a888~:::~~ bit) :::::::~8a.`~888a:::::::::88......88:::::::::;a8~".a888~:::::: ::::::::::~8a.`~888a::::::88......88::::::;a8~".a888~::::::::: 6 :::::::::::::~8a.`~888a:::88......88:::;a8~".a888~:::::::::::: :::::::::::: :~8a.`~888a:88 .....88;a8~".a888~::::::::::::::: :::::::::::::::::::~8a.`~888......88~".a888~::::::::::::::::::__ 8888888888888888888888888888......8888888888888888888888888888 2 ..............................................................~~ .............................................................. 6 8888888888888888888888888888......8888888888888888888888888888~~ ::::::::::::::::::a888~".a88......888a."~8;::::::::::::::::::: 2 (the lower :::::::::::::::a888~".a8~:88......88~888a."~8;::::::::::::::::~~ white part) ::::::::::::a888~".a8~::::88......88:::~888a."~8;::::::::::::: 6 :::::::::a888~".a8~:::::::88......88::::::~888a."~8;::::::::::__ ::::::a888~".a8~::::::::::88......88:::::::::~888a."~8;::::::: 1 (whitebit) :::a888~".a8~:::::::::::::88......88::::::::::::~888a."~8;::::-- a888~".a8~::::::::::::::::88......88:::::::::::::::~888a."~8;: 2 (red bit) ^ | -Evan M Corcoran- (and on the bottom right hand,___/ the white and red stripes are on the 'fly' edge, and the thick white stripe is on the bottom)
Source: https://ascii.co.uk/art/flags