The most common approach to Beinn Liath Mhòr starts at Achnashellach on the A890 road and goes by the right of way to Glen Torridon. This follows the impressive Coire Lair, a rugged corrie surrounded by three imposing mountains, the other two being Sgorr Ruadh (which is also a Munro) and Fuar Tholl which is ranked as one of the finest Corbetts by mountain writers. The Coire Lair path is followed for two kilometres until the path forks, here the right hand fork is taken across moorland for 0.5 kilometre until reaching the steep climb of Beinn Liath Mhòr's south east ridge, which leads directly to the summit plateau. The summit ridge consists of light coloured quartzite stones, whilst the highest point at the far end is crowned by a quartzite cairn. It is also possible to climb Beinn Liath Mhòr from Glen Torridon starting at the car park at grid reference and following the Ling path to its termination and then ascending the mountain by its western ridge.