A good resealable bag is the quiet workhorse of a warehouse, kitchen or workshop — it portions food, keeps small parts together, and lets a customer open and reclose without waste. But "zip lock bag" covers a big range of sizes and thicknesses, and the wrong one either won't hold your product or costs more than it needs to. This guide covers how to choose resealable bags in New Zealand by size, thickness and type.
What resealable bags are used for
- Food storage and portioning — keeping ingredients fresh, sampling and portion control.
- Small parts and hardware — screws, fittings and components kept together and labelled.
- Retail and display — clear bags that show the product while keeping it clean and secure.
- Stationery and organising — a low-cost way to sort and store almost anything.
Getting the size right
Resealable bags are listed as width × height in millimetres — for example 100 × 155 mm. The width is the opening; the height is the depth below the seal. Choose a size that fits your product with a little room to seal cleanly above it, rather than forcing it to the zip. Common sizes run from small coin-and-component bags (around 75 × 100 mm) up to large bags around 330 × 330 mm.
Thickness (micron) matters
The other number is the film thickness, measured in microns (mu):
- Lower micron (around 40 mu) — lighter and cheaper, fine for light contents, sampling and short-term storage.
- Higher micron (around 50–70 mu) — thicker and more puncture-resistant for heavier parts, sharp components or repeated reuse.
Match the micron to the job: sharp or heavy items want a thicker wall, while light retail or food portioning is fine on a thinner bag.
Clear vs write-on (minigrip)
Plain clear bags show the product for display and picking. Write-on / white-panel minigrip bags have a printed strip you can label by hand — handy for parts bins, samples and anything you need to identify at a glance.
The quick answer
Pick the bag by width × height so your product seals with a little room to spare, then choose the micron by weight and sharpness — around 40 mu for light contents, 50–70 mu for heavier or reusable jobs. Go clear for display and write-on minigrip for anything you need to label. Buy the pack or carton size that matches your throughput, with trade pricing for volume.
Frequently asked questions
What size resealable bag do I need?
Match the bag's width × height to your product with a little clearance above it to seal cleanly.
Sizes range from small 75 × 100 mm bags up to around 330 × 330 mm.
What does the micron (mu) rating mean?
It's the film thickness. Around 40 mu suits light contents and sampling; 50–70 mu is thicker and
more puncture-resistant for heavier parts or repeated reuse.
What's a minigrip bag?
Minigrip is a press-to-close resealable bag; the black-stripe or white-panel versions add a
write-on strip so you can label the contents by hand.
Can I buy resealable bags in bulk?
Yes — resealable bags come in packs and bulk cartons, with trade-account pricing for volume. Browse
the resealable bags range or email
sales@nzpackaging.nz for a quote on quantity.
