Inga alba can grow up to 40 m in height. It has redbark and 4 to 5 leaf pairs, with the distal pair 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 bearsfruit between January and March.