"How thick should it be?" is one of the first questions on any bespoke job — and one of the easiest to get wrong in either direction. Too thin and a panel flexes or a bracket bends; too thick and you're paying for weight you don't need and a part that won't fold the way you want. Here's how to think about it, in plain terms.
How thickness is described
We work in millimetres — 1.5 mm, 2 mm, 3 mm and so on — which is the clearest way to specify a part. You'll still hear the older gauge system (an 18 or 16 "gauge" panel), where confusingly a bigger gauge number means thinner steel. If you've been given a gauge, tell us and we'll convert it; if you're starting fresh, just think in millimetres.
What each thickness feels like in the hand
- 0.9–1.2 mm — light sheet. Easy to fold into trays, light enclosures and decorative panels, but it will flex if it spans any distance unsupported. Good where a fold or a return adds the stiffness.
- 1.5–2 mm — the everyday workhorse for brackets, signs, covers and most folded parts. Stiff enough to feel solid in the hand, still easy to bend cleanly. If in doubt, this is usually the right starting point.
- 3 mm — properly rigid. The choice for load-bearing brackets, base plates and anything that mustn't flex. Folds well but needs a bit more radius.
- 5 mm and up — plate. Structural feet, machine parts, fire-pit bodies that take real heat, heavy-duty brackets. Strong, heavy and best kept to where the strength is genuinely needed.
The cheap-and-easy mistake: over-speccing. Thicker steel costs more by weight, is slower (and so dearer) to cut, and is heavier to post. If a fold or a stiffening rib can make a thinner sheet rigid enough, that's almost always the better, cheaper part. Tell us what the piece has to do and we'll suggest the lightest gauge that does it.
Thickness and folding
Thickness changes how a part bends. Thicker steel needs a larger internal bend radius — you can't fold 3 mm plate to a knife-sharp corner the way you can thin sheet — and it springs back more, which we allow for when we set the press brake. It also affects how close a hole or cut-out can sit to a fold line before the bend distorts it. None of this is something you need to calculate; it's exactly the kind of design-for-manufacture detail we sort out when we model a folded part before cutting. The fabrication process guide explains why we draw folded work up first.
Thickness for signage and flat parts
For flat, unfolded pieces — signs, house numbers, wall art — thickness is more about how it reads and how fine the detail can be. Thicker plate looks weighty and substantial but limits how fine the lettering can go; thinner sheet holds finer detail but can feel flimsy if it's large and unsupported. Our signage guide covers the detail-versus-thickness trade-off for lettering.
Just tell us the job
You don't need to arrive with a thickness decided. The most useful thing you can give us is what the part is for — what it holds, where it sits, whether it folds, how big it is. From that we'll recommend a gauge that's strong enough without being wasteful, and quote it. Getting us involved at that stage usually saves money, not adds to it.
Read next: how custom fabrication works here and which steel lasts outdoors. See also our materials page.