Project calculators

Six calculators that work out a whole project rather than a single figure: enter your dimensions and get the cutting list, the steel to buy, the length of welds, the electrode consumption and the current it welds at.

An ordinary calculator answers one question: what a metre weighs, what current suits an electrode. These answer the question people actually ask at the steel stockist — how much of what to buy so that a particular thing of particular dimensions comes out of it.

All of them work in the browser, and all of them hand the result over in three ways: print, a CSV file for a spreadsheet, and a link that already carries your dimensions. Nothing goes to a server.

How to use them, step by step

1. Pick the project closest to yours — workbench, pedestrian gate, carport, door canopy, fence or stairs. The calculator knows how the thing is built: how many legs, rails and joints it has.
2. Enter your dimensions — outside sizes, in millimetres. Fields have limits beyond which the design stops making sense: a bench longer than three metres is a different structure.
3. Choose the section and sheet — from a list of common sizes; changing the section recalculates part lengths at once, because what gets cut to butt changes.
4. Read the cutting list — each line is a length in millimetres and a quantity.
5. Nest it and add a spare — the calculator gives net lengths; how many stock lengths to buy is shown by the cutting plan.

Example: a 1500×700 mm workbench

A 1500×700 mm bench, 850 mm high, in 40×40×2 box, with an undershelf and a 4 mm plate top — the defaults in the welding table calculator. The result:

• section in total — 12.3 m, i.e. 29.4 kg of steel in the frame;
• top of 1.05 m² — 33.0 kg, more than the whole frame;
• 62.4 kg in all to carry and stand on the floor;
• 18 joints and 2.88 m of weld;
• about 0.08 kg of electrodes or 0.05 kg of MAG wire — a handful of electrodes literally does the job, and the spare is for practice runs.

The example shows something you do not see by eye: on a bench with a thick top, more than half the weight is plate, not tube. To make the bench lighter, change the top, not the frame.

How to read the result

• Cutting list — net lengths, no saw kerf; for angled cuts the length is measured on the long edge.
• Weight — without corner radii, so two to three per cent below the tables; it does not matter for buying, but add it for transport.
• Joints and welds — weld length is taken as the section perimeter at each joint; enough to estimate time and consumables, but no substitute for a drawing with weld symbols.
• Electrodes and wire — from the deposited weight, with the same factors as the electrode consumption calculator.

What these calculators do not do

They do not check strength. A carport, stairs or a gate are structures under load — snow, people, wind — and their sections are chosen by calculation, for buildings by an engineer. The calculator assumes typical proportions and the section you pick; if the design needs a heavier one, you have to enter it. They do not price anything either, since prices depend on the supplier and the week. Full-scale products, with sections, welds and corrosion protection, are covered under carports and the neighbouring product pages.

Common mistakes when entering sizes

• Opening size instead of product size — without taking off the fitting clearance the gate will not go between the posts.
• Forgetting the top thickness — the calculator shortens the legs by the plate thickness, so enter the height to the top surface.
• Oversized section everywhere — heavy tube in the rails adds kilograms, not stiffness.
• No spare length — one mis-cut part and you are a whole length short.

Weights of individual sections and sheets, when you need one figure rather than a whole project, come from the bill of materials calculator.

Where the numbers come from

Section masses come from the same set the metal weight calculator uses; currents and consumption from the same data as the other calculators; welding settings from the table on the welding square tube page. None of these calculators has numbers of its own: if it did, sooner or later they would drift away from the rest of the site.

Author: Dmitry Frolov, welder and metal fabricator Updated: 28 September 2026