Steel pedestrian gate: cutting-list calculator

Give the width and height of the leaf and you get the cutting list for the frame, the ribs and the brace, the mass of steel and sheet, the length of welds and the current.

A worked example: a 1000 × 1800 leaf

The commonest size: about a metre of opening, an 1800 mm leaf, a frame of 40×20×2, two vertical ribs, a brace and two posts set 700 mm into the ground.

Mass is worked out without the corner radii of the section, so it comes out two to three per cent below the standard tables. No allowance is added for saw kerf or cutting errors: when buying, add one commercial length.

The brace matters more than the wall thickness

A rectangle of four tubes is a mechanism, not a structure: four hinges and no bracing at all. However well it is welded, it folds into a parallelogram over time, and the gate starts catching the ground with the corner on the lock side.

The cure is not thickness but geometry. A brace splits the rectangle into two triangles, and a triangle does not change shape. The direction matters:

• Right: from the bottom corner on the hinge side to the top corner on the lock side. It works in compression and the weight of the leaf travels down it into the post.
• Worse: the other way round. Then it works in tension through the welds, and any weak weld turns into sag.

Posts

Wind pushes on solid sheet harder than people expect: a 1 × 1.8 m leaf is almost two square metres of sail. The post is therefore chosen for overturning moment, not for the weight of the gate.

• Section from 60×60×3 for leaves up to 1.2 m, and 80×80×3 for anything wider or from 2 m tall.
• Embedment below the frost line, usually 0.8–1.2 m.
• Gravel in the bottom of the hole, 100–150 mm, so water drains instead of freezing under the end.
• Cap the top of the post. An open tube collects water and splits along the seam in the first hard frost.

Welding settings

A 2 mm wall is thin material and the corner of the frame burns through in a second. The values are the same as on the welding square tube page; the calculator above shows the row for the wall thickness you chose.

Materials and weight, part by part

A 1000 × 1800 leaf in 40×20×2 tube breaks down like this:

• Frame: two stiles of 1800 mm and two rails of 920 mm — the rail fits between the stiles, so it is two tube widths shorter than the leaf.
• Two ribs of 1720 mm and a brace of about 1951 mm.
• Posts — two of 2500 mm (1800 plus 700 in the ground). The list shows them in the frame tube.
• 0.5 mm profiled sheet — 1.8 m², about 8 kg.

The leaf alone is about 10.8 m of tube and 19 kg, about 27 kg with the sheet. If the posts are made from 60×60×3 as they should be (5.37 kg per metre), two 2.5 m posts weigh about 27 kg — as much as the whole clad leaf. The gate has only 10 joints and 1.2 m of weld; the wire comes to about 20 grams.

Tools you need

• A welder good for 90–110 A on MIG or 70–90 A with a 2.5 rod for the frame; for hinges on a 60×60×3 post, up to 140 A or a 3.2 rod.
• A flat table or board at least the size of the leaf, 1 × 1.8 m: on an uneven base the frame is welded crooked from the start.
• Magnetic squares, 4 clamps, tape, level.
• An angle grinder with cutting and flap discs.
• Hardware: two or three weld-on hinges, a bolt or lock, and wedges to set the gaps when hanging.

Setting out and tacking

1. Lay the stiles and rails on the table, set the corners with magnetic squares and clamp.
2. Check the leaf diagonals: on 1000 × 1800 they are about 2059 mm and must agree within 2 mm.
3. Tack the four corners crosswise — top left, bottom right, top right, bottom left — and check the diagonals again.
4. Mark the ribs from one edge of the leaf so the gaps come out equal, and tack both ends.
5. Fit the brace to the tacked frame: its ends run at about 62° and 28°, and it is more accurate to take them off the frame than to cut from the list in advance.

Step-by-step order with settings

1. Posts in concrete, to level and string, with gravel in the bottom of the hole. While the concrete gains strength, weld the leaf.
2. Leaf frame. 2 mm wall: 0.8 mm wire, 90–110 A, 17–19 V, or a 2.5 mm rod at 70–90 A. The corner is where it burns through: run from the middle of the face towards the corner in short stretches. More on avoiding burn-through in welding thin metal.
3. Ribs and brace — same settings, last.
4. Hinges to the leaf. Set for the thin frame wall, arc on the heavier hinge.
5. Hanging. Stand the leaf in the opening on wedges, set the gaps at hinges and lock and the level, and only then tack the hinges to the post. 3 mm post: 0.8–1.0 mm wire, 120–140 A, 19–21 V, or a 3.2 mm rod at 90–120 A. Open, close, check, then weld out.
6. Clean, prime, paint, then screw on the sheet.

How to keep the leaf true

A gate is the item in this section most sensitive to distortion: a couple of millimetres of twist means a leaf that catches the post or will not close on the bolt. The order that prevents it:

• Everything on the table and in clamps until fully cold.
• Corners across the diagonal, not round in order: the shrinkage of one weld is balanced by the opposite one.
• Joint faces in turn — wide face, opposite wide face, then the narrow ones.
• Brace ends alternately in short stretches: a long weld at one end pulls the frame into a rhombus.

Painting

Dress the welds with a flap disc, degrease, apply anti-corrosion primer and two coats of enamel, brushing the welds first. Mask the hinges while painting: paint in the knuckle sets and the gate starts to squeak and stiffen; grease the hinges afterwards. Cap the post tops and open frame ends. Fit the sheet to a painted frame — there is no painting behind it later.

How long it takes

This is the least welding in the section: 10 joints and 1.2 m of weld. The time goes into preparation:

• Posts — holes, setting, concrete and a break while it gains strength.
• The leaf — cutting, assembly on the table, diagonals and welding.
• Hanging — the fiddliest stage: gaps, level, and checking the swing before the hinges are welded out.
• Paint and sheet — with drying times as per the product sheet.

If the gate goes into a new fence, work out the posts and rails at the same time in the fence calculator. Typical gate designs are reviewed on the gates and wickets page.

What usually spoils the job

Beginner mistakes on a gate

• Posts in the same tube as the frame. A 40×20 post gives way to the wind within a season; a post starts at 60×60×3.
• Frame welded on a floor or bench that is "roughly flat". The unevenness turns into twist in the leaf: one corner will not sit flat.
• Hinges welded to the post without wedges. The leaf is set by eye, the gaps differ and the bolt misses.
• No clearance under the leaf for a hump in the ground, paving or snow in the swing — the gate stops opening in winter.
• Paint in the hinges. Mask them for painting and grease them after.

Author: Dmitry Frolov, welder and metal fabricator Updated: 27 September 2026