Eucalyptus alba is a tree which grows to a height of 5 to 18 m with a spreading crown 5 to 15 m wide. The trunk is often bent and has smooth pinkish red to white or cream-coloured, powdery bark. The leaves on young plants are arranged alternately, egg-shaped to more or less round, 10–20 cm long and 8–12 cm wide. The adult leaves are egg-shaped to lance-shaped, 5–12 cm long and 5–8 cm wide with both sides a similar shade of green.
The flower buds are arranged in groups of seven on a peduncle 4–14 mm long. The buds are oval to more or less spherical, with an operculum 3–5 mm long and 4–7 mm wide, similar in dimensions to the floral cup. White flowers appear from August to November and are sometimes profuse. The fruit is cone-shaped to hemispherical, 4–7 mm long and 5–8 mm wide.