Gary Lee James, a yard hand at Ward Brothers (Malton) Ltd's depot at South Bank, Teesside, was stripping clothing frames weighing up to 120kg (18st 13lb) when he was pinned at the back of a container as five of the heavy racks fell in January 2019.
The 30-year-old, of Middlesbrough, died three days later having suffered asphyxia, cardiac arrest and brain injury.
The firm pleaded guilty to a health and safety breach and was sentenced at Teesside Crown Court, with the judge hearing dangerous work was being carried out by "trial and error".