Eucalyptus subtilis is a mallee that typically grows to a height of and forms a
lignotuber. It has smooth grey to light pale orange coloured bark. Young plants and
coppice regrowth have dull green to bluish leaves that are long and wide. Adult leaves are arranged alternately, held erect, dull to slightly glossy green, linear, long and wide with a pointed apex and the base tapering toward a petiole long. The flower buds are arranged in leaf
axils on an unbranched
peduncle long, the individual buds on
pedicels up to long. Mature buds are spindle-shaped, long and wide with a conical
operculum. Flowering occurs between February and June and the flowers are cream-coloured or white. The fruit is a woody cup-shaped to shortly barrel-shaped
capsule long and wide with the valves near rim level. ==Taxonomy and naming==