Twenty-foot general purpose cargo containers are used by most international shipping companies. Forty-foot, hi cube and half height sizes are also popular. The efficiency gained allows lower costs for moving larger loads and offer an appealing alternative to more expensive air transport.


The maximum capacity of a 20-foot ocean container is close to 48,000 lbs. However, factors such as interior dimension, container brand and the shipped product will affect final weight. The cubic capacity or product of height times width times depth is the most relevant calculated figure and a typical 20-foot vessel approaches 1,400 cubic feet.


The dimensions of 20-foot containers that follow International Shipping Organization standards are typically 20 by 8 by 8.5 feet. Containers are made of a combination of steel and brass for handling ocean conditions, and corrugated side panels provide greater protection from damage, according to W&K Container.


Several terms are important for understanding container measurements. The rating is the capacity of the container plus its contents. The tare mass is the empty weight of the container, and the payload is the rating minus the tare mass. There are also variations within the internal structure of containers that affect final payload capacity.