Resealable bags go by a lot of names. Press seal, ziplock, grip seal, snap lock, click seal: walk into three different warehouses and you'll hear three different terms for what is often the same bag. That makes ordering harder than it should be, especially if you're comparing suppliers and one lists "ziplock bags" while another lists "press seal bags" at a different price.
This guide clears up the terminology, explains how each closure type actually works, and helps you choose the right size and thickness for your products. QIS Packaging stocks the full range of resealable ziplock bags in sizes from 38x50mm up to 380x510mm, so every bag mentioned below is one we sell and ship Australia-wide.
Resealable, press seal, ziplock: what do these names actually mean?
Here's the short version. "Resealable bag" is the umbrella term for any bag you can open and close repeatedly without tape, staples or a heat sealer. "Press seal" describes the most common closure mechanism: two plastic ridges moulded into the bag mouth that click together when you press them. "Ziplock" is a genericised brand name that Australians use for the same thing.
So in most cases, a press seal bag and a ziplock bag are the same product. The distinction that actually matters is between the different closure types on the market:
- Press seal (grip seal): interlocking ridges you press shut with your fingers. The workhorse. Cheap, reliable, and available in the widest range of sizes.
- Slider seal: a plastic tab that slides along the track to open and close it. Easier for arthritic hands or gloved use, but dearer and mostly limited to consumer freezer bags.
- Adhesive lip (resealable flap): a fold-over flap with a sticky strip, common on cellophane and garment bags. Reseals a few times, but it's really designed for presentation rather than repeated access.
- Zipper pouches: stand-up pouches with a press seal built into a gusseted bag, used for retail food packaging like coffee, granola and treats.
QIS's resealable range is built around press seal closures because they offer the best balance of price, seal reliability and size availability for Australian businesses. The same collection includes write on panel bags and clear stand-up pouch bags, both covered below.
How a press seal closure works (and why it's so widely used)
A press seal is two moulded polyethylene profiles, one ridge and one channel, running across the mouth of the bag. Press them together and the ridge snaps into the channel, giving you a seal that is airtight enough for day-to-day storage and dust protection. Open and close it hundreds of times and it still works, because the profiles are part of the bag itself rather than a glued-on extra.
Press seal bags are made from LDPE (low density polyethylene), the soft, clear, flexible film also used in standard poly bags. LDPE gives you good clarity for scanning barcodes or identifying contents, decent puncture resistance, and food-safe storage. If you want the full rundown on how LDPE compares to its stiffer cousin, our LDPE vs HDPE guide covers it.
What press seal bags are good at: parts and hardware, jewellery and small components, sample packs, pharmaceuticals and first aid, coin and collectable storage, food portioning, and keeping paperwork or manuals clean inside larger cartons.
What they're not built for: liquids under pressure, long-term barrier protection against oxygen (use a vacuum bag for that), or heavy sharp items that need a thicker gauge than the bag carries.
Choosing the right size and thickness
Two decisions matter here: the bag dimensions and the film thickness, measured in microns (µm).
Sizing: measure the item, then add room
Bag sizes are quoted width x length in millimetres, measured on the usable inside of the bag. Measure your item, then allow roughly 10-20mm of clearance on the width so the item slides in without stressing the seal. Some popular picks from the range:
- 38x50mm and 50x75mm: jewellery, beads, screws, seeds, pills and samples.
- 75x100mm and 100x150mm: small parts, coins, craft supplies, spice portions.
- 150x230mm and 150x205mm: phone accessories, cables, documents folded once, food portions.
- 230x330mm (A4): paperwork, manuals, clothing accessories, artwork protection.
- 280x380mm up to 380x510mm: garments, larger components, bulk food storage.
Thickness: 50µm vs 75µm vs 100µm
The range runs from 50µm (standard duty) through 75µm (heavy duty) to 100µm on the write on panel line. As a rule of thumb, 50µm suits lightweight contents and general storage; 75µm adds puncture resistance for metal parts, tools and anything with corners; 100µm is for repeated handling and heavier items. Thicker film also feels more substantial in the hand, which matters if the bag is customer-facing. For a deeper explanation of micron ratings, see our poly bag thickness guide.
Popular picks across the three duty levels:
Write on panel bags: the labelling shortcut
A write on panel bag is a standard press seal bag with white printed strips on the front. Grab a permanent marker and label the contents, batch number, date or customer name directly on the bag. No printed labels, no label guns, no stickers that peel off in the cool room.
They're the default choice for pharmacies, pathology and medical suppliers, parts departments, and any warehouse doing kitting or small-batch dispatch. QIS stocks write on panel bags from 50x75mm up to 230x320mm, most in a robust 100µm film that stands up to repeated handling.
Stand-up pouch bags: resealable packaging that retails well
The same collection includes clear stand-up pouch bags with a bottom gusset and press seal closure, in sizes from 138x205mm to 190x260mm. The gusset lets the bag stand upright on a shelf, which makes pouches the pick for retail food products like lollies, granola, coffee beans and pet treats. Add a printed label and you have shelf-ready packaging without the cost of custom printed film.
Can resealable bags store food and go in the freezer?
Yes. LDPE press seal bags are suitable for direct food contact and are widely used for portioning, sandwich storage and freezing. A couple of practical notes: press the seal closed from one end to the other to push out excess air before freezing, and choose 75µm or heavier for the freezer, since thin film gets brittle at low temperatures. Our freezer bag guide covers which bag types handle freezing best.
For long-term freezer storage of meat or anything sensitive to freezer burn, a vacuum sealed bag will outperform any press seal closure, because a press seal is airtight in everyday terms but not a true oxygen barrier.
Buying resealable bags in bulk
Resealable bags are sold by the carton (typically 500 or 1,000 bags depending on size), and per-unit pricing drops sharply as quantities rise. A few tips from our warehouse:
- Standardise on fewer sizes. Two or three sizes cover most operations, and consolidating your order into larger cartons of fewer lines costs less than many small cartons of many lines.
- Match thickness to the job, not the catalogue. Paying for 100µm film to store paperwork is wasted money; using 50µm for bolts will cost you in split bags.
- Ask for volume pricing. If you're ordering pallet quantities or need a size we don't list, request a quote and our team will price it directly. QIS backs quotes with a 5% price-beat guarantee.
Orders placed before 12pm on weekdays are dispatched the same day, with delivery to Sydney, Melbourne, Brisbane, Perth, Adelaide and regional areas across Australia.
Frequently asked questions
Are press seal bags and ziplock bags the same thing?
For practical purposes, yes. Ziplock is a brand name that has become the everyday word for press seal (grip seal) bags. If a supplier lists "ziplock bags" and another lists "press seal bags" in the same size and micron, you're comparing the same product.
Are resealable press seal bags airtight and waterproof?
They're airtight and water resistant in everyday use: contents are protected from dust, moisture and spills. They're not a substitute for vacuum sealing or hermetic packaging where a true oxygen or moisture barrier is required.
What micron thickness do I need?
50µm handles light contents such as paperwork, samples, confectionery and craft items. Step up to 75µm for metal parts, tools, and freezer use. Choose 100µm (write on panel range) where bags are opened and reused constantly or contents are heavy.
Are resealable bags food safe?
QIS press seal bags are made from LDPE, which is suitable for direct food contact. They're widely used for food portioning, storage and retail packing of dry goods.
Can resealable bags be recycled in Australia?
LDPE is technically recyclable as soft plastic, but kerbside rules vary by council and dedicated soft-plastics collection is still patchy in many areas. Check your local council's guidance. Reusing the bags many times before disposal is the most reliable way to cut their footprint.
What sizes do resealable bags come in?
The QIS range spans 38x50mm (jewellery and pill size) through to 380x510mm (garment and bulk storage size), including an A4-friendly 230x330mm bag. See the full size list on the resealable ziplock bags collection.
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