Repton was born in Bury St Edmunds, the son of a collector of excise, John Repton, and Martha ("née" Fitch). In 1762 his father set up a transport business in Norwich, where Humphry attended Norwich Grammar School. At age twelve he was sent to the Netherlands to learn Dutch and prepare for a career as a merchant. However, Repton was befriended by a wealthy Dutch family and the trip may have done more to stimulate his interest in 'polite' pursuits such as sketching and gardening.