Restrictions on the minimum size and weight of cargo do not exist.
Cargo, whose weight consists 150 kg and more, is classified as heavy cargo. When you send a heavy cargo requires prior approval from carrier.
The total weight and volume of packages is limited only by the size of cargo compartments of aircraft. Dimensions of cargo compartments on all aircraft types are different so if you have any questions related to exceed of the standards, you should seek advice from the experts.