Described is unit for weighing containers (2) comprising a line (4) for transporting the containers (2) extending along a first path (P) which passes through a region (R1) for weighing and provided with a plurality of seats (5) for supporting the containers (2) arranged in succession along the first path (P); a plurality of elements (6) for vertical movement of the containers (2), each configured at the weighing region (R1) to make contact with and move vertically one of the containers (2) so as to place it in a raised position (PS1) disengaged from the corresponding supporting seat (5); a plurality of elements (7) for retaining the containers (2), each configured for retaining one of the containers (2) in the raised position (PS1); a plurality of weighing devices (8), each associated to, and carrying, a retaining element (7) for measuring the weight of a container (2) retained by the retaining element (7).