Born on May 21, 1985 in Cornwall, England, Calvin attended Fowey Community College. By the age of 12 Calvin was appearing in school productions and amateur theatre. At the age of 16, Calvin joined the National Youth Theatre and subsequently trained at Mountview Academy of Theatre Arts.
Upon graduating, Calvin made his screen debut alongside Keira Knightley in The Duchess. Early television credits include Casualty and Demons.
In 2008 Calvin was cast in the lead role of Darren in the horror movie Tormented and received critical acclaim for his portrayal.
Further television credits include The Sarah Jane Adventures, Law & Order:UK, Doctor Who and the Golden Globe nominated Dancing On The Edge.