Inga alba can grow up to 40 m in height. It has red bark and 4 to 5 leafpairs, with the distalpair 6.1–10 cm long and 2.5—7.7 cm wide. The rachis is 5—13.5 cm long and wingless. The glands are cone-shaped, the stipules obsolete. The inflorescences are short, the shaft is 4–20 mm long and the rachis 5–8 mm long. The flowers are pale green and the stamen are white. The fruits are flat up to 14 cm long and 2 cm wide. It flowers between August and November and bears fruit between January and March.