How to Verify Stainless Steel Thickness Before You Pay

Thickness is where quiet money disappears in stainless fabrication. A worktable quoted with a 1.2 mm top that arrives at 1.0 mm looks identical in photos, flexes more in use, and cost the factory roughly 17% less steel. Here is how thickness really works, and how to check it.

Nominal vs actual thickness

Sheet steel is sold by nominal thickness, and rolling tolerances mean the actual sheet measures slightly under the nominal figure. On top of that, some quotes are written for a lower actual gauge than the headline number suggests. The fix is contractual, not technical: your purchase order should state the minimum actual thickness (for example, "top sheet: nominal 1.2 mm, actual not below 1.15 mm"), not just "1.2 mm". We write it this way on confirmed orders.

Measure it: caliper method

• Use a micrometer or a digital caliper with 0.01 mm resolution - a ruler cannot judge sheet thickness.
• Measure at a free edge or a cut-out, never across a bend or a weld, where the metal has stretched or built up.
• Take at least three points per sheet (two corners and the middle) and record them; a single point can sit on a thick spot.
• Check the top, the undershelf and the legs separately - they are often different gauges on purpose.

Cross-check it: the weight method

Stainless steel weighs about 7.9 g per cubic centimetre. So a flat sheet's weight is predictable:

Weight (kg) = length (m) x width (m) x thickness (mm) x 7.9

Worked example: a 1200 x 600 mm worktable top at a true 1.2 mm should weigh about 1.2 x 0.6 x 1.2 x 7.9 = 6.8 kg for the sheet alone. If the same top weighs 5.7 kg, it is a 1.0 mm sheet whatever the invoice says. Weigh the whole unit and compare it against the sum of its sheets, legs and frame - a shortfall of more than a few percent means thinner steel somewhere.

What we do on your order

During pre-shipment inspection we measure tops and shelves with a caliper at several points and photograph the readings, and the measurements go into the photo report you approve before loading. If a measurement is under the confirmed minimum, the piece does not ship.