Poly Mailer Thickness Guide
Compare film thickness using the same units and wall convention, then evaluate the complete bag for your intended shipment.
1. Use clear units
Film thickness is commonly expressed in micrometres (μm). One millimetre equals 1,000 μm. A mil is one thousandth of an inch and equals 25.4 μm; it is not a millimetre. Ask the supplier to state the units in the quotation rather than relying on a number without a unit.
2. Confirm single-wall or combined thickness
A flattened bag has a front and a back wall. Confirm whether the stated thickness describes one wall or the combined reading across both walls. The same number can describe different constructions if the convention is unclear. For multilayer film, confirm whether the quoted value is the total thickness of one finished wall.
3. Assess more than thickness
Thickness alone does not establish puncture resistance, seal quality or suitability for sharp or heavy items. Material composition, construction, contents and handling conditions also matter. Share the product weight and shape, and discuss whether separate protective packaging is needed. Do not infer recycled content, recyclability or biodegradability from thickness or appearance.
4. Agree on measurement and acceptance
Request a sample of the proposed construction. Agree on the measuring method, sampling locations, tolerance and acceptance criteria before production. Keep the approved specification with the artwork and purchase documents. Paper grammage is a different measurement and should not be presented as an equivalent film thickness.