ChatGPT answer 

On plastic bags, “PE 0.4” usually refers to two different things combined into one marking:

1. PE

PE stands for Polyethylene, which is the most common plastic used to make plastic bags.

It can be HDPE (high-density polyethylene) or LDPE (low-density polyethylene).

PE plastics are flexible, waterproof, and commonly used for shopping bags, trash bags, and packaging.

2. 0.4

The 0.4 normally indicates the thickness of the plastic, but the exact unit depends on local practice:

In many Asian countries (including Singapore, Malaysia, China):

0.4 usually means 0.4 mil

1 mil = 0.0254 mm

0.4 mil ≈ 0.01 mm (10 microns)

This would be considered a very thin plastic bag, typically used for:

Light retail items

Food packaging

Convenience-store bags

Put together: “PE 0.4”

It means:

A polyethylene plastic bag with a thickness of about 0.4 mil (≈10 microns)

Important note

There is no single global standard for this marking. Some manufacturers may use “0.4” as an internal grade or nominal thickness, not a precisely measured value.

If you are asking because of:

Singapore plastic bag regulations

Quality comparison

Environmental or reuse concerns

I can explain how PE 0.4 compares to thicker bags (e.g. 0.6, 0.8, 1.0) or whether it meets local rules.