Two plastic bags can look almost identical on the shelf and behave completely differently once you load them up. One stretches and hugs the product. The other crackles, holds its shape and tears in a straight line if you nick the edge. That difference is usually LDPE versus HDPE, and picking the wrong one is how businesses end up double-bagging, replacing split cartons or fielding complaints about bags that split on the way to the car.
Here is what actually separates the two materials, and how to decide which belongs in your storeroom.
The short answer
LDPE (low-density polyethylene) is soft, flexible and clear. It is the material behind flat poly bags, layflat tubing, freezer bags and most food-contact packaging. Choose it when you need clarity, puncture resistance, heat sealing or cold-storage performance.
HDPE (high-density polyethylene) is stiffer, thinner-feeling and slightly hazy. It is the material behind singlet checkout bags, produce roll bags and many bin liners. Choose it when you need maximum carry strength for the least material and cost, and you do not need the bag to look premium.
Both are polyethylene. Both are recyclable through soft-plastic collection streams. The difference is how tightly the polymer chains pack together, and that one structural detail drives everything else.
What LDPE gives you
LDPE has a branched molecular structure, which stops the chains packing neatly. The result is a softer, lower-density film with more give.
Clarity. LDPE is genuinely clear rather than milky. Staff can identify contents without opening the bag, and customers can read a label through it. For flat poly bags used in produce, bakery and deli work, that visibility is half the value.
Puncture and impact resistance. Because LDPE stretches before it fails, it absorbs a knock instead of splitting. Drop a bag of frozen chicken pieces on a concrete floor and LDPE will usually deform rather than burst.
Cold performance. LDPE stays flexible at freezer temperatures. Stiffer films can go brittle in cold storage and crack when handled, which is why LDPE dominates freezer and chiller applications.
Heat sealing. LDPE seals cleanly and reliably. If you need tamper-evident packaging or a sealed portion pack, an LDPE bag and a bench-top heat sealer will do it in a couple of seconds.
Custom sizing. LDPE is also supplied as layflat tubing, so you can cut and seal your own bag lengths for odd-shaped products instead of buying a stocked size that almost fits.
The trade-off: gram for gram, LDPE is less tear-resistant than HDPE. To carry the same load you generally need a thicker film, which costs more per bag.
What HDPE gives you
HDPE has a linear, tightly packed structure. It is denser, stiffer and stronger per micron of thickness.
Strength at low thickness. This is the whole point of HDPE. A very thin HDPE film can carry a surprising load, which is why supermarket checkout bags have always been HDPE. Less material, more carry capacity, lower cost per bag.
Stiffness and shape. HDPE holds its form, so bags stay open at the counter and are quicker to load in a queue. The familiar crinkle and rustle is HDPE.
Chemical and moisture resistance. HDPE handles a wide range of contents without degrading, which makes it a sensible choice for waste and general-purpose liners.
Heat tolerance. HDPE has a higher softening point than LDPE, which matters for warm contents.
The trade-off: HDPE is hazier, it tears more readily once the film is nicked, and it does not have the same soft-touch feel that retail and gift packaging usually want.
LDPE vs HDPE at a glance
| LDPE | HDPE | |
|---|---|---|
| Feel | Soft, flexible, slightly stretchy | Stiff, crinkly, rustles |
| Clarity | Clear | Hazy or translucent, often white |
| Strength per micron | Lower | Higher |
| Puncture resistance | Higher | Lower |
| Tear resistance once nicked | Higher | Lower |
| Freezer performance | Excellent | Fair |
| Heat sealing | Excellent | Good |
| Typical thickness range | 35µm to 150µm | Around 15µm to 40µm |
| Typical products | Flat poly bags, freezer bags, layflat tubing, carton liners | Singlet checkout bags, produce roll bags, bin liners |
| Best for | Food packing, cold storage, display, sealed packs | Carry bags, high-volume checkout, waste |
Five questions that settle it
Does the bag touch food?
Both materials can be manufactured food grade, but the material spec alone is not the answer. What matters is whether the resin is virgin food grade rather than recycled remill. Every bag in the QIS LDPE poly bag range is virgin food grade and safe for direct contact with bread, produce, meat, fish, dairy and prepared meals. If your product touches food, ask the supplier that question specifically rather than relying on the letters LDPE or HDPE.
Does it go in a freezer?
LDPE, without much argument. It stays pliable below zero and takes a heat seal, which is what you want for long-term frozen storage. HDPE gets noticeably brittle in the cold.
Is the customer carrying it out of the store?
That is HDPE territory. Singlet checkout bags are built for exactly this: handles moulded into the bag, stiff enough to stay open at the counter, strong enough for a decent load at a low cost per bag.
Does anyone need to see what is inside?
LDPE. Clear film means staff pick the right item first time and customers can read a label without opening anything. If you need genuinely crystal-clear presentation rather than merely clear, look at polypropylene bags instead, though PP is stiffer and less suited to freezer use.
Are you sealing the bag?
LDPE seals more forgivingly and gives a stronger, more consistent weld. If sealed packs are part of your process, build around LDPE.
Getting the thickness right
Material choice is only half the decision. Thickness in microns (µm) does most of the practical work, and it is where buyers waste the most money in both directions.
QIS stocks LDPE poly bags in five thicknesses:
- 35µm: everyday, high volume, light duty. Fresh produce, bakery items, small retail goods, dry ingredients.
- 50µm: general purpose food packing and retail. A step up in puncture resistance for irregular or slightly heavier contents.
- 75µm: heavier products, bulk food, light industrial. Butcher wholesale portions, freezer storage of meat and fish.
- 100µm: frozen goods, sharp or heavy items, freight and industrial packaging.
- 150µm: the toughest jobs. Machinery parts, building materials, heavy freight.
Ordering heavier than the job needs adds cost with no benefit. Going too light means split bags and double-bagging, which is more expensive than buying the right gauge in the first place. If you are not sure where you sit, our poly bag thickness guide walks through it with worked examples.
Popular options to start with
Where the plastic bag bans fit in
This is the part most buyers get caught out by. Single-use lightweight plastic shopping bags are now restricted across Australia, but the exact thickness thresholds, exemptions and enforcement dates differ between states and territories, and they have changed more than once.
The practical upshot: barrier bags and produce bags used inside a store are treated differently from the carry bag a customer takes home. QIS stocks HDPE singlet bags in reusable-rated gauges, including lines flagged as QLD compliant, but you should confirm the current requirement in your own state before committing to a large order. Our Queensland plastic bag ban guide covers the detail, and if you are unsure, give the team a call on 1800 555 343 and we will tell you what is currently compliant where you trade.
Recycling both materials
LDPE and HDPE are both recyclable, and both are accepted through soft-plastic collection points rather than kerbside recycling in most Australian council areas. Do not put either in the yellow bin unless your council specifically says otherwise, because soft plastics jam sorting machinery at materials recovery facilities.
Keeping the two streams clean helps. Bundling LDPE poly bag offcuts with HDPE liners is fine for soft-plastic collection, but if you generate volume, ask your waste contractor whether they will take them separated. Segregated streams are worth more.
Frequently asked questions
Is LDPE or HDPE stronger?
It depends which kind of strength you mean. HDPE has higher tensile strength per micron, so a thinner HDPE film carries more weight. LDPE has better puncture and tear resistance, so it survives sharp corners and rough handling better. For carrying, HDPE. For protecting, LDPE.
Can you tell LDPE and HDPE apart by touch?
Usually, yes. Scrunch the bag. HDPE crackles loudly and springs back with a papery rustle. LDPE goes quiet and stays scrunched. HDPE also tends to look milky or white, while LDPE is clear.
Are LDPE bags food safe?
LDPE bags made from virgin food grade resin are safe for direct food contact. Bags made from recycled remill are not, because there is no way to verify what the recycled content previously held. Every LDPE poly bag QIS stocks is virgin food grade.
Which one should I use for bin liners?
Both are used. HDPE liners are thinner and cheaper for general waste. LDPE liners handle sharp or heavy waste better without splitting. QIS stocks a range of bin liners and garbage bags if you want to compare grades.
Can I heat seal HDPE?
Yes, though the seal window is narrower and the result is less consistent than LDPE. If sealing is part of your daily process, LDPE will give you fewer failed seals and less rework.
Can I get either material custom printed or in a non-stock size?
Yes. QIS can arrange custom-manufactured sizes and printed bags in both materials. Send the specs through our quote request form or call 1800 555 343 and we will come back with options and lead times.
Still not sure which material your job needs?
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