The short answer
HDPE is denser, stiffer, stronger and handles more heat, so it is used for bottles, drums, pipe and crates. LDPE is softer, more flexible and clearer, so it is used for film, bags and squeeze bottles. The difference comes from how branched the polymer chains are.
HDPE and LDPE are both polyethylene, but they behave like different materials. Picking the wrong one usually shows up as parts that are too floppy, film that will not seal or stretch, or bottles that crack under load.
Side by side
| Property | HDPE | LDPE |
|---|---|---|
| Density | 0.941–0.965 g/cm³ | 0.910–0.930 g/cm³ |
| Chain structure | Linear, little branching | Many long branches |
| Stiffness | High | Low; soft and flexible |
| Tensile strength | ~20–32 MPa | ~8–15 MPa |
| Melting point | ~125–135°C | ~105–115°C |
| Clarity | Translucent to opaque | Clearer, especially in film |
| Chemical resistance | Excellent | Very good |
| Recycling code | 2 | 4 |
| Typical uses | Bottles, drums, crates, pipe, totes, caps | Film, bags, squeeze bottles, coatings, liners |
Typical ranges for general-purpose grades; individual grades vary with melt index and density.
Why they differ
HDPE chains are mostly straight, so they pack into a dense, highly crystalline structure: stiff, strong and opaque. LDPE chains carry long side branches that keep them from packing tightly, which lowers the density and crystallinity and makes the material soft, flexible and clearer. LLDPE has short branches from a comonomer instead of long ones, which gives LDPE-like density with better toughness and puncture resistance. See LDPE vs. LLDPE.
Choosing between them
Choose HDPE when
- The part must be rigid: bottles, drums, crates, totes
- It carries load or holds liquids under pressure
- It sees higher temperatures, such as hot fill or dishwashers
- Pipe and chemical containers
Choose LDPE when
- It must flex or squeeze: bottles, tubes, lids
- Clear film, bags and shrink film
- Easy heat sealing and coating
- Soft-touch or low-temperature flexibility matters
Melt index matters as much as density
Within each family, melt index (MI) sets how the resin processes. Low-MI grades suit blow molding, pipe and film strength; high-MI grades suit injection molding and thin walls. When matching a grade, match density and melt index together. See melt flow index explained.
Grades we source
We source HDPE, LDPE and LLDPE for injection molding, blow molding, film and extrusion, from one gaylord to a railcar, with a COA on every lot, tested to ASTM or ISO methods. See polyethylene, HDPE injection grades and LDPE film grades.
Common questions
What is the main difference between HDPE and LDPE?
Branching. HDPE has straight chains that pack tightly, so it is denser, stiffer and stronger. LDPE has many long branches, so it is softer, more flexible and clearer.
Which is stronger, HDPE or LDPE?
HDPE. It has higher tensile strength and stiffness and holds more heat. LDPE is tougher in the sense of being flexible and stretchy, which suits film and squeeze bottles.
How do you tell HDPE from LDPE?
Density is the reliable test: LDPE is about 0.910 to 0.930 g/cm³, HDPE about 0.941 to 0.965. The recycling codes are 2 for HDPE and 4 for LDPE. By feel, HDPE is stiffer and more opaque.
Can HDPE and LDPE be blended?
Yes, and it is common in film and molding to balance stiffness and flexibility. Blends behave between the two, depending on the ratio and the grades.
Where does LLDPE fit?
LLDPE has short branches from a comonomer. It has similar density to LDPE but is tougher and more puncture resistant, which is why it dominates stretch and liner film.
Tell us the polyethylene grade you run now
A polymer chemist reviews every request, then matches your grade or finds a qualified equivalent and prices it.
What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
- Color (natural, black or a custom match)
- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
- Ship-to city and state or province