How are angle steel specifications typically expressed?

Angle steel specifications are denoted by side length (a) × side thickness (t) in millimeters, often supplemented by length and weight per meter. For example, "∠50×5" means equal-side angle steel with 50mm side length and 5mm thickness; "∠75×50×6" indicates unequal-side angle steel (75mm long side, 50mm short side, 6mm thickness). Common equal-side specifications range from ∠20×3 (light-duty, ~1.18kg/m) to ∠200×24 (heavy-duty, ~71.18kg/m), while unequal-side types include ∠30×20×3 to ∠200×125×18. Length is usually 6m, 9m, or 12m (fixed-length delivery), and weight per meter is calculated via the formula: Weight (kg/m) = 0.00785 × t × (2a - t) for equal sides, or 0.00785 × t × (a + b - t) for unequal sides (a=long side, b=short side).