Work out steel weight per metre instantly with clear inputs, formula shown and shareable results.
Any steel section weighs its cross-sectional area times the density of steel, 7850 kg/m³. Working in millimetres, mass per metre is area in mm² times 7.85 divided by 1000. That single relation covers round, square and flat bar; only the area formula changes.
Unit weight
kg/m = area mm² x 7.85 / 1000
Areas
Round = pi d²/4; square = a²; flat = width x thickness
kg/m = area mm² x 7.85 / 1000. Any steel section weighs its cross-sectional area times the density of steel, 7850 kg/m³.
The density relation does, but you must use the true area. For tube use the annulus, and for rolled beams take the tabulated area from the section tables rather than approximating.
This calculator takes 3 inputs: Section shape, Diameter, side or width, Thickness (flat bar only). The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.