The thickness of poly bags is measured in mils, but this can be confusing. Let’s take a look at what these thicknesses mean and how they affect the bag's performance.
We are used to measuring in inches and feet, so mils don’t really make sense. However, this is how industry standards work in the United States. We will explain mil thickness in plain terms and help you choose the right thickness for your packaging requirements.
If you’re also trying to understand how size accuracy is defined during production, visit our guide: Width, Length, and Gauge Tolerances for Plastic Bags.
What Does “Mil” Mean in Plastic?
In packaging, a “mil” is a unit of measurement equal to one-thousandth of an inch (0.001”). So a 2 mil poly bag is 0.002 inches thick. This is the standard way poly film thickness is measured in North America.
How Is Plastic Thickness Measured?
Manufacturers use precision tools, such as micrometers, to measure film thickness during production. Every batch is tested to meet specific mil ratings for quality and consistency.
At Packaging Friends, we follow strict quality control practices at each production stage. That’s how we know that every bag matches its listed thickness and performs as expected. If you have any doubts about the thickness of our bags, please contact us.
Why Thickness Matters in Plastic Packaging
Bag thickness matters in terms of durability, flexibility, and cost. In general:
● Thinner bags (1–2 mil): Best for lightweight items like apparel, food, or instruction manuals.
● Standard bags (3–4 mil): Ideal for retail and eCommerce packaging. They are strong and affordable.
● Thicker bags (5–6+ mil): Ideal for hardware, tools, or industrial items with sharp edges.
In our experience, 4 mil bags are a go-to for warehouse teams that need stronger puncture resistance without overspending on a thicker bag. They’re a sweet spot for strength and flexibility.
Common Mil Thickness Levels and Their Uses
| Thickness | Typical Use | Description |
|---|---|---|
| 1–2 mil | Light-duty | Great for food, garments, documents |
| 3–4 mil | Standard | Retail-ready, ideal for most products |
| 6+ mil | Heavy-duty | For metal parts, construction, or industrial equipment |
Packaging Friends has a wide selection of poly bag thicknesses, from lightweight 1 mil options for delicate items to stronger 8 mil bags built for heavy-duty protection. Depending on the level of durability and performance you expect, we will match the right poly bag.
Understanding Mils, Microns, and Gauge
Different regions use different systems to measure thickness:
● Mils = U.S. standard
● Microns = Mainly used in Europe (1 mil ≈ 25 microns)
● Gauge = Common in the UK, but also used in the U.S. for films and bags. Gauge is another unit, often equal to one-hundredth of a mil. A 2 mil thickness is the same as a 200 Gauge.
2 mil x 100 = 200 Gauge.
While they all measure film thickness, they’re not always interchangeable. Always check the unit listed before placing an order.
How to Choose the Right Thickness for Your Product
Before you choose the thickness for your poly bags, consider:
● What’s being packaged
●Weight and shape of the product
● Risk of puncture or tear
●Storage and transport conditions
● Required shelf life
For example, we’ve seen that customers shipping metal bolts and tools almost always go with 6 mil to prevent tearing. Meanwhile, soft goods or clothing are fine in 2 mil, while 4 mil and above are ideal for freezing.
If you’re unsure, our team can help you decide the best thickness for your needs.
Once you know your desired thickness, make sure to measure your bag size correctly with our Measurement Guide.
Packaging Friends for Your Poly Bags
Mil thickness helps you balance strength, clarity, and cost. You want to choose bags with the right thickness for your products to keep them safe and protected, without overspending.
Packaging Friends offers high-performance poly bags in different thicknesses, depending on their use. We have the right thicknesses for lightweight packaging or heavy-duty protection. Orders over $1,000 qualify for free shipping with bulk discounts.
Frequently Asked Questions
Is a higher mil always better?
Not necessarily. It actually depends on the product. Thicker bags cost more and are less flexible, so choose a bag thickness and type that match the product inside.
How do I convert mils to microns?
1 mil equals about 25 microns.
Can thicker plastic still be transparent?
Yes, thicker bags can stay clear depending on the resin type and finish.
What is the thickest plastic bag available?
Packaging Friends offers bags up to 8 mil and custom options for special applications.
What thickness should I choose for packaging parts or hardware?
Use 4–6 mil bags for metal parts or tools to prevent punctures and tears.
Are thicker bags more expensive?
Yes, as they use more material. However, they often last longer and can be reused.
Can I recycle plastic bags regardless of thickness?
Most poly bags can be recycled if they are clean.
Do thicker bags affect how clear the plastic looks?
Slightly, but quality materials keep even thicker bags clear and smooth.
What is the standard thickness for retail or eCommerce packaging?
Retail bags are usually between 2 and 3 mil, which is strong enough for most products and shipping needs.
Are mil and gauge the same thing?
No, they’re different units. Mil is used in the U.S., and gauge is mostly used in the U.K.; they don’t convert directly. Gauge is another unit, often equal to one-hundredth of a mil. A 2 mil thickness is the same as a 200 Gauge: 2 mil x 100 = 200 Gauge.
What thickness is used for heavy industrial or construction applications?
Industrial sheeting or liners often range from 1 to 6 mil depending on the job.
Does bag thickness affect sealing quality?
Yes, thicker bags may require higher sealing temperatures for a proper seal.