The naitional banner o the Principality o Andorrae wis adoptit in 1866. The banner is a vertical tricolour o blue, yellow, an reid wi the coat o airms o Andorrae in the centre. Awtho the three vertical bars mey at first appear tae be o equal width, the centre yellae bar is slichtly wider than the ither twa sae that the ratio o bar widths is 8:9:8. The oweraw banner ratio is 7:10.
The design is relatit tae the banners o Fraunce an Spain, the twa states that pertect the unthirldom o the sma state. A banner o three bars is seemilar tae that o the French Tricolore, while the pattern o a wider middle stripe can be notit on the Spaineyie banner. The blue an reid o the Andorran banner are an aa foond on the French banner, wi reid an yellae an aa bein the principal colours o the Spainyie banner. Frae 1806 tae 1866, Andorrae's banner wis a vertical bi-color o yellae an reid. The motto in the coat o airms in the middle stripe Virtus Unita Fortior means "Strength Unitit is Stranger".
The design is seemilar tae the banners o Romanie, Moldovae, Chad an the banner o Queen's University in Ontario, Canadae. Aw o thir are vertical tricolours o blue, yellow, an reid, but unlik that o Andorrae, thair banners aw hae stripes o equal breadth.