Eucalyptus koolpinensis is a straggly tree that typically grows to a height of and occasionally to and forms a
lignotuber. The bark is grey to grey-white in colour and rough to the ends of branches. It is tightly held box-type bark, becoming tessellated on the trunk. Young plants and
coppice regrowth have dull bluish green, more or less round to egg-shaped or kite-shaped leaves long and wide. The adult leaves are arranged alternately, the same dull blue-green on both sides, more or less round to kite-shaped, long and wide on a
petiole long. The flower buds are arranged on the ends of branchlets on a branching
peduncle each branch with seven buds. The peduncle is long, the individual buds on
pedicels long. Mature buds are pear-shaped, long and wide with a beaked
operculum. Flowering occurs between April and June and the flowers are creamy white. The fruit is a woody, more or less cup-shaped
capsule long and wide with the valves close to rim level. The seeds are dark brown, oval and long. ==Taxonomy and naming==