Eragrostis variabilis is a perennial grass with tufted, erect culms usually measuring 40–80 cm in height or taller. The culms are glabrous or scaberulous, significantly below the panicles. Its leaves are simple and alternate, with blades that are usually flat near the base and involute in the upper part. The blades can reach up to 50 cm in length and about 1 cm in width. The upper surfaces of the blades are scaberulous and sometimes villous near the base, while the lower surfaces are glabrous. The leaf sheaths are glabrous or puberulent at the apex and on the collar and can be villous at the throat. The ligule is a ciliate membrane less than 0.5 mm long and lacks stipules. Its panicles are narrow, up to 40 cm long, and can be somewhat open or dense and spike-like. The branches are strongly ascending to spreading, with a scabrous or pubescent axis, which can be glabrous in the lower part. The axils are sometimes pilose, and the pedicels are glabrous or scabrous. The spikelets (pictured) are 8-12(-14)-flowered, measuring 5-10 mm in length, with subequal glumes that are 2-3 mm long. The keels of the glumes are usually strongly scaberulous, with an acuminate or attenuate apex; the first glume is 1-nerved, and the second is 3-nerved. The lemmas are imbricate, 2.5-3 mm long, and scabrous towards the apex, with an acuminate apex. The palea is nearly as long as the lemma, with a scabrous-ciliate keel. The caryopsis is dark reddish brown, ellipsoid to ovoid, 0.6-1.0 mm long, and delicately striate. It is found in habitats such as dunes, grasslands, open sites in dry forests, and exposed slopes, ridges, or cliffs between 0-1,130 meters.