Common angle steel sizes are specified by the length of the two equal or unequal legs and their thickness. For equal - angle steel, common sizes range from 20×20×3 mm (20 mm leg length, 3 mm thickness) to 200×200×24 mm. Unequal - angle steel has dimensions like 25×16×3 mm (25 mm long leg, 16 mm short leg, 3 mm thickness). These sizes follow international standards such as ASTM in the United States and national standards like GB/T 706 in China. The variety of sizes allows angle steel to be used in diverse applications, from small - scale DIY projects to large - scale industrial and construction works.