Structural steel beams, typically referred to as "I beams," range from 4 inches tall to 44 inches tall. A structural engineer may also design a custom beam if none of the standard beam sizes meet the needs of the application.
The Steel Construction Manual by the American Institute of Steel Construction provides a complete list of the sizes and shapes of steel beams that are used in the construction industry. Steel beams are named not only by their depth but also by their weight per linear foot. For example, a W8x28 is an 8-inch-tall beam that weighs 28 pounds per linear foot.
Many people typically refer to steel beams as "I beams." This is because when looking at the cross section of the beam, it looks like the letter I. However, the construction industry actually refers to these as "W shapes," since they are officially called "wide flange beams."