How to count the steel of a gate, a railing or a grille
Updated October 11, 2026
Metalwork in square tube is ordered in tubes of a standard length, by section. The count follows from the dimensions, the bar spacing and the tube sections of the workshop drawing.
1. What to take from the drawing
Note the size of the work, the section and wall thickness of the frame tube and of the infill tube, the spacing of the bars from centre to centre, and for a gate the embedment of the posts in the ground. They are editable starting values in the tool, never a built-in reference.
2. Frame, bars and posts
The frame is the perimeter of each leaf plus its intermediate rails. Between the uprights, bars stand at the spacing: ⌈clear width ÷ spacing⌉ − 1, each as long as the clear height between the rails. The posts are as high as the work plus the embedment. A railing has a post at each spacing plus one, and its horizontal rails run along its length.
Worked example: a single-leaf gate of 3 × 2 m
Frame tube 40 × 2 mm, bars 20 × 1.5 mm every 12 cm, one intermediate rail, posts embedded 40 cm, tubes of 6 m, 5 % offcuts:
Frame: 2 × (300 + 200) + 292 = 1 292 cm = 12.92 m; posts 2 × 2.40 = 4.80 m; 17.72 m of frame tube.
Bars: ⌈292 ÷ 12⌉ − 1 = 24, each 1.92 m, i.e. 46.08 m.
Weight: 17.72 m × 2.386 kg/m + 46.08 m × 0.871 kg/m = 82.4 kg; 4 frame tubes and 9 bar tubes to buy.
Weight and paint
A metre of square tube weighs (side² − (side − 2 × wall)²) × density ÷ 1 000 kg, with the density of steel (about 7.85 g/cm³) editable. The surface to paint is the outer perimeter of each section times its length.
What this does not cover
The count checks neither strength nor safety: the guard height, the gap between bars, the wind and impact loads and the fixings come from the regulation that applies to the work and from the workshop drawing.
General information, checked at the date shown. It does not replace advice from a professional for your situation.
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