Manufacturers measure steel angle iron by determining each leg's length and thickness. Length measurements start at the point where the two sides meet and go all the way to the end of each leg. Thickness measurements only apply to the thickest point on the angle iron, as many types of angle iron taper off toward the end of each leg.
On most sizes of steel angle iron, each leg is the same length. For these products, manufactures may only provide a single leg length measurement. However, some speciality types of steel angle iron have unequally sized legs. For these types of steel angle iron, the manufacturer usually labels one leg "A" and the other "B" in order to distinguish the two, and uses "C" to refer to the angle iron's maximum thickness.
Steel manufacturers also occasionally specify weight measurements for steel angle iron according to the weight per each foot of span. Depending on the grade of steel used and the dimensions of the product, steel rolling mills produce steel angle iron at lengths of 20 to 40 feet. However, most manufacturers and retailers do not list length measurements for steel angle iron, as customers typically specify which lengths they require, and the retailer then cuts the pieces accordingly.