Calder is the son of science writer Nigel Calder and the grandson of the late Lord Peter Ritchie Calder. In 1962, Calder joined the Woodcraft Folk, and took his first independent trip with the group to the Lake District. That same year after the USSR sent nuclear warheads to Cuba, Calder's parents decided that with Gatwick airport only two miles away they were in the line of a potential Soviet target. The family moved to Guernsey in the Channel Islands, for a short holiday while the danger passed. The school he attended, Thomas Bennett in Crawley, compulsorily taught Russian, which Calder comments was not useful on regular school and family trips to France.
Calder's first job was a cleaner for British Airways at Gatwick, and later as a security guard. He began during this period writing budget travel guidebooks, starting with the Hitch-hiker's Manual: Britain. He later studied for a degree in Mathematics at University of Warwick, while also perfecting his love of Hitchhiking around Europe. At one point he was the holder of the record for the quickest hitchhike between Land's End and John o' Groats
After university, Calder wrote several books and series of guides including the Traveller's Survival Kit series and Backpacks, Boots and Baguettes. His first broadcast as a travel expert was on Simon Bates program Studio B15 on BBC Radio 1 in 1980. Classic FM: UK radio station of the year
Calder became travel editor for The Independent in 1994, and shortly afterwards began presenting for BBC 2's Travel Show until the programme ended in 1999. He then contributed to several BBC 1 shows, including Perfect Holiday and Departure Lounge. Calder presented the final film in the last edition of the long-running Holiday programme in 2007. He continues to contribute to various BBC programmes, and regularly comments as an expert on travel issues for other radio and TV stations.
Calder currently presents The Travel Show, a weekly travel phone-in, on the London talk radio station LBC.