Between 1956 and 1966, Calder wrote for the magazine New Scientist, serving as editor from 1962 until 1966. Since that time, he has worked as an independent author and TV screenwriter. He has conceived and scripted thirteen major documentaries and series concerning popular science subjects broadcast by the BBC and Channel 4 (London), with accompanying books. For his television work he received the Kalinga Prize for the Popularization of Science during 1972. During 2004, his book Magic Universe was shortlisted for The Aventis Prizes for Science Books.

Nigel Calder is the son of the late Lord (Peter) Ritchie-Calder, a brother of the historian Angus Calder and the father of travel writer Simon Calder. His other children are Sarah (business writer), Penny (museums writer and consultant), Jo (working in an IT company) and Kate (public relations consultant). His wife Liz is his literary agent and was formerly an adviser on language teaching for the London Chambers of Commerce.

Calder is a long-standing sceptic of global warming. As early as 1980, he predicted that within 20 years "the much-advertised heating of the earth by the man-made carbon-dioxide ‘greenhouse’ [will fail] to occur; instead, there [will be] renewed concern about cooling and an impending ice age". Calder participated in the polemic film The Great Global Warming Swindle. He also co-authored The Chilling Stars. Regarding global warming, Calder has said that "Governments are trying to achieve unanimity by stifling any scientist who disagrees. Einstein could not have got funding under the present system."