Thickness is usually the first spec a buyer gets wrong on a steel sheet order — not because it is hard to measure, but because it is easy to default to “whatever we used last time” instead of working it out from the job. Order too thin and a panel oil-cans or a bracket deflects under load; order too thick and you are paying for steel (and freight, and harder cutting) the application never needed. Here is a practical way to land on the right gauge or plate thickness.
Gauge Numbers vs Millimetres
Sheet metal thickness is often quoted as a “gauge” number, which — like pipe’s NPS — is a label from a standard table, not a direct measurement. Higher gauge numbers mean thinner steel, which trips up buyers used to the opposite convention. For mild steel on the common U.S. Standard Gauge table:
| Gauge | Thickness (mm) | Thickness (in) |
|---|---|---|
| 10 | 3.42 mm | 0.1345″ |
| 12 | 2.66 mm | 0.1046″ |
| 14 | 1.90 mm | 0.0747″ |
| 16 | 1.52 mm | 0.0598″ |
| 18 | 1.21 mm | 0.0478″ |
| 20 | 0.91 mm | 0.0359″ |
| 22 | 0.76 mm | 0.0299″ |
Gauge-to-mm conversion can vary slightly between standards and suppliers, so for anything load-bearing or dimensionally critical, specify the thickness in millimetres directly rather than by gauge number alone. See our full Steel Grade & Thickness Reference Guide for the complete chart. Above roughly 6 mm, steel is generally sold and specified as plate rather than by gauge, in millimetres directly.
Matching Thickness to the Job
As a general guide across common industrial uses:
- ~0.76–0.91 mm (20–22 ga) — light cladding, false-ceiling panels, decorative panels and other non-structural skins where weight and cost matter more than stiffness.
- ~1.2–1.5 mm (16–18 ga) — equipment enclosures, cabinets, duct work and light brackets that need to hold their shape but carry little direct load.
- ~1.9–2.7 mm (12–14 ga) — machine guards, heavier enclosures, mounting brackets and panels that see regular handling or moderate mechanical stress.
- ~3.4 mm and above (10 ga and heavier) — load-bearing brackets, chassis components and fabrication where stiffness under real load is the priority.
- 6 mm plate and above — machinery bases, heavy structural fabrication, and pressure-rated applications governed by IS 2002 / IS 2041.
Treat these as a starting point, not a substitute for calculation on anything genuinely load-bearing. Four factors usually decide the final number:
- Load and deflection — what weight or force the part sees in service, and how much it is allowed to flex.
- Forming and bend radius — thicker material needs a larger minimum bend radius and more tonnage to form; going thicker than needed can make a part harder to fabricate, not just heavier.
- Corrosion allowance — outdoor or wet-environment parts are sometimes specified a size up to allow for long-term material loss.
- Weldability and handling — very thin sheet is prone to warping during welding; very thick sheet needs higher heat input and different joint prep.
Grades We Stock
K. K. Steels stocks MS sheets and plates to IS 2062 across the full gauge and plate range, along with stainless steel sheets and plates, and boiler/pressure-vessel plate to IS 2002 / IS 2041. See our Steel Sheets & Plates page for grades and stock sizes.
Not sure which thickness your application needs? Share the application — load, environment and how it will be formed — with our team on WhatsApp at +91 99878 92312 or email info@kksteels.com and we will help you spec it.
