The specific epithet megacarpa is from the Greek meaning 'large fruit'.

[2] Castanopsis megacarpa grows as a tree up to 36 metres (120 ft) tall with a trunk diameter of up to 90 cm (35 in).

Its roundish or ellipsoid nuts measure up to 7.5 cm (3.0 in) long.

[2] Castanopsis megacarpa grows naturally in Thailand, Borneo, Peninsular Malaysia and Singapore.

[1][2] Its habitat is dipterocarp, kerangas or lower montane forests up to 1,400 m (4,600 ft) altitude.