HDPE suits thin, low-cost vest bags; LDPE, usually blended with LLDPE, suits printed retail bags that need a soft feel and a clean print surface. That is why a quote for 50 µm LDPE die-cut bags and another for 20 µm HDPE vest bags can both answer the same brief. The two films behave very differently in the hand, at the till and on the press, and recycled polyethylene changes the picture again. This article compares them for printed carrier bags; for formats, handles and ordering, start from the custom printed plastic bags hub.
What is the practical difference between LDPE and HDPE bags?
HDPE makes thin, stiff, crinkly bags with high tensile strength, well suited to low-cost vest carriers. LDPE makes softer, quieter, glossier bags that need more thickness for the same load but print and present better, which is why it dominates printed retail bags with die-cut, patch and loop handles.
Both are polyethylene; the difference is molecular structure. HDPE has long, mostly linear chains that pack tightly into crystalline regions, giving higher density and stiffness. LDPE has many long side branches that keep chains apart, giving a softer, more amorphous and more transparent film.
| Property | HDPE | LDPE | LLDPE |
|---|---|---|---|
| Typical density (g/cm³) | ~0.941-0.965 | ~0.910-0.940 | ~0.915-0.925 |
| Feel and sound | Stiff, papery, rustles loudly | Soft, smooth, quiet | Soft, slightly rubbery, stretchy |
| Clarity and gloss | Hazy, matt | Clear, glossy | Fairly clear |
| Tensile strength at same thickness | High | Moderate | Moderate to high |
| Puncture and impact resistance | Moderate; can split once punctured | Good | Very good |
| Tear propagation | Tends to tear easily along the machine direction once started | Resists tearing reasonably | Strong resistance |
| Typical thickness for carrier bags | ~10-25 µm | ~35-100 µm | Blended into LDPE or HDPE |
| Typical bag formats | Vest / T-shirt, produce rolls | Die-cut, patch, soft loop, mailing bags | Toughening component in blends |
Ranges are indicative and vary by grade and supplier.
Why HDPE feels crinkly
The crystallinity that gives HDPE its strength also makes it stiff and noisy. When folded it holds creases and rustles; when held up to light it looks milky. For a supermarket vest bag this does not matter, and the stiffness helps bags open on a dispenser. For a fashion retailer it can read as cheap, which is why HDPE is rarely chosen for brand-led retail bags even when it would carry the load.
Why LDPE needs more thickness
LDPE's softness means lower tensile strength and stiffness at the same gauge. A die-cut LDPE bag carrying a few kilograms typically needs two to three times the thickness of an HDPE vest bag carrying a similar load. The extra film is part of the appeal: thicker LDPE bags feel substantial, are reused more and give a smooth surface for print.
LDPE vs LLDPE: what changes for carrier bags?
Linear low-density polyethylene (LLDPE) is rarely used alone for carrier bags but is blended into LDPE (and sometimes HDPE) to raise puncture resistance, tear strength and seal toughness. A typical retail bag film is an LDPE/LLDPE blend; the ratio is tuned by the extruder for handle type, load and processing.
LLDPE has short, regular branches rather than LDPE's long ones. That gives better stretch and puncture resistance, and it lets converters down-gauge: a blend can reach a target strength with less film than straight LDPE. The trade-off is that LLDPE-rich films can be harder to cut cleanly at the handle punch and slightly less clear. Metallocene LLDPE grades offer further toughness for thin films at higher resin cost.
When comparing quotes, ask whether "LDPE" means pure LDPE or a blend. Two 50 µm bags described as LDPE can perform quite differently.
How does recycled PE change a carrier bag?
Recycled polyethylene can replace part or most of the virgin resin in a carrier bag, but it usually brings a grey or off-white tint, occasional specks or gels, and more variable strength. Most recycled-content bags are blends, and the recycled share is chosen to balance compliance targets against appearance and performance.
Two sources are common:
- Post-industrial recycled (PIR): offcuts and scrap from film production and conversion, usually clean and consistent. Often counted as recycled content, but check the definition used by the law or scheme you are reporting under; for UK Plastic Packaging Tax, pre-consumer waste stops counting from 1 April 2027.
- Post-consumer recycled (PCR): used film collected from households and businesses. More variable in colour, odour and contamination; stronger environmental claim.
| Recycled share (indicative) | Typical effect on bag |
|---|---|
| Up to ~30 % | Small loss of clarity; light colours still achievable; strength close to virgin with adjusted recipe |
| ~30-50 % | Visible tint; white masterbatch often added; some specks; may need extra thickness for the same load |
| ~50-100 % | Grey or dark base; bright colours need a white ink underlay; strength more variable; print density harder to control |
These are rules of thumb. Actual results depend heavily on the recyclate grade.
Recycled content and printing
The base colour of recycled film limits how bright a print can look. Bright yellow or pastel shades printed directly onto grey PCR film will shift. The options are a white-pigmented film, a co-extruded film with a virgin or white outer layer and recycled core, or a white ink underlay. Co-extrusion is often the best compromise: the recycled share counts towards your target while the print surface stays clean. Ink adhesion on recycled film can also vary, so corona treatment levels should be checked. Details are in printing on plastic bags.
Recycled content and the law
Recycled content now carries financial and regulatory weight:
- UK: Plastic Packaging Tax applies at £228.82 per tonne from 1 April 2026 to plastic packaging containing less than 30 % recycled plastic. UK manufacturers and importers of 10 tonnes or more of plastic packaging a year, filled or unfilled, must register. A bag at 30 % or more recycled content is outside the tax, but the claim must be supported by evidence.
- EU: The PPWR, Regulation (EU) 2025/40, sets minimum recycled content for plastic packaging from 1 January 2030 at the earliest, with a 35 % figure for plastic packaging outside the contact-sensitive and beverage-bottle categories, rising by 2040. How exemptions and calculation rules apply to carrier bags should be confirmed against the implementing acts as they are published.
- Food contact: post-consumer recycled PE is generally not suitable for bags that touch unwrapped food unless it comes from a recycling process authorised for food contact. For bags carrying only packed goods this is less of a constraint.
The full legal picture by market is in plastic carrier bag regulations in the EU, UK and US.
Which film suits which bag?
Match the film to the handle and the use: HDPE for vest bags and thin high-volume carriers, LDPE/LLDPE blends for printed retail bags with die-cut, patch or loop handles, and co-extruded recycled blends where recycled content matters and appearance still counts.
| Use case | Recommended film (typical) | Why |
|---|---|---|
| Grocery or market vest bag | HDPE, sometimes with LLDPE | Strength at very low thickness, low cost; check thin-bag rules |
| Fashion or boutique die-cut bag | LDPE/LLDPE blend, white or coloured | Soft feel, gloss, clean print |
| Heavier retail goods, patch handle | LDPE/LLDPE blend, higher thickness | Toughness at handle, reuse |
| Reusable bag for life, soft loop | LDPE/LLDPE with recycled content | Durability for repeat use; recycled content supports PPT position in the UK |
| Event or trade-show bag | LDPE blend, die-cut or loop | Print area, perceived quality |
| Mailing bag | Co-extruded LDPE, often with recycled core | Opacity, puncture resistance, recycled share |
For how each handle construction distributes load, see plastic bag handle types. For how to translate a load into a micron, gauge or mil figure, see plastic bag thickness.
Is HDPE or LDPE more recyclable?
Both are polyethylene and can usually be recycled together in film streams, so the choice between HDPE and LDPE matters less for recyclability than avoiding mixed materials. A bag made entirely from PE, including its patch or loop handle, is easier to recycle than one with clip handles, paper labels or non-PE components.
In practice, film bags are often collected through store take-back points rather than household bins, and access varies by country and region. In England, Simpler Recycling originally set 31 March 2027 for plastic film collections from households and businesses, but Defra announced in July 2026 that this will be delayed to 2030. Under the PPWR, EU packaging must meet recyclability grade A, B or C from 1 January 2030, and the design-for-recycling criteria will define what counts. Recyclability claims on the bag need to match real collection access; see recyclable vs compostable packaging.
Checklist for specifying the film
- State the bag format and handle type first; the film follows from them.
- Ask for the film recipe: HDPE, LDPE, LDPE/LLDPE blend and approximate ratio.
- Specify film colour (natural, white, coloured) and whether the outer layer must be white for print.
- Give a recycled content target, the source (PCR or PIR) and the evidence you need.
- State the maximum load per bag and how it will be tested.
- Note the market of use so thickness and recycled content can be checked against local rules.
- Request a sample in the proposed film with your print, especially for high recycled content.
Send these points with your artwork when requesting a quote via the custom printed plastic bags hub or our contact page. For general advice on structuring the enquiry, see how to write a packaging RFQ.