Little Mell Fell is a small U-shaped area of high ground, about 1 square mile (2.6 km2) in area, north of Ullswater and east of Great Mell Fell. Its summit is a symmetrical rounded grassy dome in the south-east corner of the fell which reaches a height of 505 m, 32 m lower than Great Mell Fell. Two short grassy spurs extend from this dome: one to the north and one to the west. The western spur then turns northwards so that a deep valley is enclosed between the two spurs, drained by the upper reaches of Thackthwaite Gill.