Kalophrynus calciphilus was recently described from Gunung Mulu National Park in eastern Sarawak. It is endemic to the karst forest within the park where it occurs at elevations between 70 and at least 1200 m a.s.l. It is one of the most abundant species in this type of forest. Males can be found calling from the entrance of burrows and crevices in the ground. The call is a single, short, pulsed note.

The reproductive mode and the tadpoles of the species are unknown. It is a medium-sized member of the genus, reaching 30 mm, snout-vent-length in males, 39 mm in females. 

The back and flanks are black during the night. During the day, the colouration lightens to brown and a fine pattern of reticulated black markings becomes visible. A white line runs along each side of the body from the tip of the snout to the groin. Like other species of the genus, K. calciphilus secretes a sticky mucus when molested. (Photo courtesy © Maximilian Dehling).