Understanding Film Gauge: Why Thickness Matters in Poly Bags

When ordering poly bags, one of the first questions you’ll hear is: “What thickness do you need?” In the industry this is often called “gauge,” but poly film thickness is properly measured in mils — and it drastically impacts how a bag performs. Whether you’re packaging heavy items, fragile parts, or food, the wrong thickness leads to waste, breakage, or compliance issues.

What Is a Mil?

A mil is one-thousandth of an inch (1 mil = 0.001″). For LDPE film, thickness directly impacts:

• Strength — thicker film resists punctures and tears
• Clarity — thinner film is clearer, but weaker
• Feel — thicker bags feel more rigid and heavy-duty
• Barrier — moisture protection improves slightly with thickness

At M Plastics, we produce film from a light 0.75 mil up to heavy-duty 6+ mil, depending on the application.

Choosing the Right Thickness

• 0.75–1.25 mil — light dust covers, food service liners
• 1.5–2 mil — standard poly bags, light industrial use
• 2.5–3 mil — medium-duty liners, parts packaging
• 4+ mil — heavy industrial items, sharp edges, box liners under load

How We Control Thickness

Our blown film lines use extrusion controls to hold uniform thickness across the roll, and runs are checked for consistency before converting.

Final Thoughts

Film thickness is not a guess — it’s a critical spec that determines how well your product is protected and what you pay per bag. For a deeper dive into cost trade-offs, see why thickness matters for durability and cost, or request a quote for a recommendation on your next order.