Micron describes film thickness; it does not describe the bag's width, length or order weight. To compare a polybag quote, ask for thickness in micron and confirm whether it describes one wall of film or both walls measured together.
This guide explains the units used in thickness enquiries. The conversion examples are mathematics, not a list of stocked PackPoly thicknesses, product test results or recommended load ratings. Existing product specifications and prices stay on their product pages. Minimum order: 25 kg.
Micron, millimetres and mil
One micron is one micrometre, written µm. A millimetre contains 1,000 micrometres. A mil is one-thousandth of an inch, not one millimetre. NIST's conversion tables define 1 mil as exactly 25.4 micrometres.
| Thickness expression | Equivalent | How to use it |
|---|---|---|
| 1 micron | 0.001 mm | The micron is the unit used for PackPoly thickness enquiries. |
| 25 micron | 0.025 mm | A unit-conversion example, not a load or stock specification. |
| 50 micron | 0.050 mm | Twice the numeric thickness of 25 micron, without implying twice the strength. |
| 1 mil | 25.4 micron | Multiply mil by 25.4 to obtain micron. |
| 2 mil | 50.8 micron | Keep the exact conversion when comparing an imported specification. |
Sources: NIST length units and NIST Special Publication 1038 conversion tables.
Do not rely on “gauge” without its convention
A supplier saying “100 gauge” has not yet told you an unambiguous micron specification. Ask what that supplier means by gauge, obtain the equivalent micron value in writing and confirm the wall basis. Do not apply an automatic gauge conversion when the convention is unknown.
A clear quotation line is more useful than a shorthand label: material, construction, width x length, single-wall micron and any agreed tolerance. If you are matching an existing bag, send a sample description and request measurement rather than estimating thickness from how it feels.
Single wall versus two layers
A flat bag has a front and back wall. Measuring the closed bag can put both walls under the instrument. Ask whether a thickness reading was taken on one film layer, and keep that basis consistent between quotes. Zips, reinforced handles, seams and folded gussets are different features and should not be mistaken for the main-body film thickness.
Thickness does not tell the whole performance story
Do not select a bag only by micron. LDPE, HDPE and PP are different materials; resin or blend, seals, construction, product edges and handling conditions also matter. A higher micron number alone is not a verified carrying capacity, puncture rating or shelf-life claim.
Tell us whether the product is bulky, has sharp edges, needs a display finish, will be stacked or requires a particular closure. If a bag must meet a strength, barrier, temperature or food-contact requirement, ask for product-specific confirmation. Tell us if the bag will touch food and we will confirm a suitable grade.
Why micron affects pieces per kg
For otherwise comparable bags, more film thickness adds material to each bag, so the number of pieces per kg changes. Gussets, flaps and zips also affect weight. Use a measured sample weight or an agreed piece count for purchasing; a simplified flat-film calculation is only an estimate.
Our pieces-per-kg guide explains the calculation. A quoted 1 kg price is still the unit rate per kilogram; it does not conflict with the 25 kg minimum order or mean that each bag holds 1 kg.
A practical thickness enquiry checklist
- Material and actual use, including product contact and storage conditions
- Bag construction, dimensions and closure
- Single-wall thickness in micron and any required tolerance
- Whether you need a sample matched or a performance requirement checked
- Printing, colour, total order weight in kg and delivery destination
Request a specification-based quote. The appropriate thickness needs confirmation for your product; the conversion table is not a universal thickness recommendation.
Record usable dimensions with the bag-size measuring guide. Compare zip lock bag listings, or use the Karachi packaging supplier guide to prepare a wider packaging enquiry.