Beinn an Oir is a Corbett of 785 m in Argyll and Bute. Its key col is at sea level, so all 785 m of its height counts as drop.
Nothing higher stands within 56.0 km; the nearest higher summit is Caisteal Abhail (859 m), to the south-east. It is the most isolated register hill in Argyll and Bute: higher ground is 56.0 km away. Its drop is the 6th greatest among the Corbetts, behind Goatfell at the top. It overtops all four of its nearest neighbours; the tallest of them, Beinn Shiantaidh, reaches 757.2 m. In the database's Jura, Scarba and Colonsay region it is the highest of three register hills, above Beinn Shiantaidh and Beinn a' Chaolais. It shares its height of 785 m with Beinn na Caillich (Highland, NG795066), Allen Crags and Great Carrs. On the Corbetts height ladder it sits between Arkle (785.9 m) and Beinn na Caillich (Highland, NG795066) (785 m). The summit is marked by a trig point, inside a shelter. It falls on two OS 1:50,000 sheets, 60 and 61.
