LDPE, HDPE or PP: what is the difference?
LDPE is soft, flexible and seals well; HDPE is stiffer, denser and crackles when you handle it; PP is clearer and withstands more heat. Zip bags, flat bags and tubular film are mostly made of LDPE. Recycling codes: PE-LD 4, PE-HD 2, PP 5.
As of: 18.10.2026 · Reviewed by: Editorial team Elke Plastic GmbH · Information provided without guarantee.
The three plastics compared
| Property | LDPE (PE-LD) | HDPE (PE-HD) | PP |
|---|---|---|---|
| Density (guideline) | approx. 0.91 to 0.94 g/cm³ | approx. 0.94 to 0.97 g/cm³ | approx. 0.90 to 0.91 g/cm³ |
| Feel | soft, stretchy | stiffer, crackly | firm, smooth |
| Appearance | clear to slightly cloudy, glossy | milky to opaque | clear (OPP: crystal clear) |
| Melting range (guideline) | approx. 105 to 115 °C | approx. 125 to 135 °C | approx. 160 to 170 °C |
| Recycling code | 4 (PE-LD) | 2 (PE-HD) | 5 (PP) |
| Typical bags | flat bags, zip bags, drawstring bags, slider bags, tubular film | thin T-shirt bags, carrier bags, sacks | flat bags, cone bags, OPP/CPP bags |
The values are typical guideline values. The data sheet of the individual item is binding.
What does this mean for choosing a bag?
- LDPE for flexible, stretchy bags that close well: for example zip bags, flat bags or tubular film.
- HDPE for thin, rustling bags with high strength at low thickness.
- PP and OPP for clear, stiff bags with a glossy look, for example bakery flat bags or cone bags.
Our range consists mainly of LDPE, supplemented by PP, OPP, CPP and PA/PE laminates. Examples: Flat Bags, Ziplock Bags and Tubular film.
LDPE and HDPE for food
Both plastics are generally suitable for contact with food. What matters is the specific item: it must be expressly manufactured for food contact and documented as such. More on this: Food-safe: glass and fork symbol and evidence.
Recycling codes at a glance
The number in the triangle names the material: 2 stands for PE-HD, 4 for PE-LD, 5 for PP. The meaning of all codes is explained in Recycling codes for plastic. General information on PE bags: PE bags.
Frequently asked questions
Which is stronger: LDPE or HDPE?
HDPE is stiffer and firmer; LDPE is more stretchy and is less likely to tear under load. How strong a bag is also depends heavily on its thickness.
How can I tell LDPE and HDPE apart?
LDPE feels soft and tends to be clear. HDPE is stiffer, looks milky and crackles. The surest way to tell is the recycling code: 4 stands for PE-LD, 2 for PE-HD.
Are LDPE and HDPE food-safe?
The material is generally suitable for food. Whether a particular bag is food-safe is shown by the item’s marking and declaration of conformity.
Why are zip bags mostly made of LDPE?
LDPE is soft and can easily be formed and sealed into a zip closure. That is why zip bags are usually made of LDPE.
What distinguishes PP from PE?
PP is clearer, stiffer and withstands more heat than PE. It carries recycling code 5, PE-LD code 4 and PE-HD code 2.