Walk into any packaging warehouse and you'll see poly bags in a dozen variations. Three types account for most orders: flat bags (open top), zip lock bags (resealable), and self-adhesive bags (peel-and-seal).
Each one solves a different problem. Here's how to choose.
📄 Flat Bag
Open top, heat-seal or tie
Lowest cost per bag
🔒 Zip Lock Bag
Double-track zipper, reusable
Best for repeated access
📬 Self-Adhesive Bag
Peel-and-seal, no equipment
Clean, professional look
Flat Bag -The Workhorse
A flat bag is exactly what it sounds like: a simple bag with an open top and a sealed bottom (or side). No closure mechanism -you fill it and seal it with a heat sealer, tape, or tie.
- Best for: Products that are sealed once and opened by the end customer. Garments, bread, hardware parts, dry goods.
- Advantages: Lowest cost per bag, fastest production, simplest design.
- Considerations: Requires a sealing step (heat sealer or tape). Not reusable.
- Price range: quoted by specification (virgin LDPE).
Zip Lock Bag -The Reusable Solution
A zip lock bag has an integrated zipper at the opening. Press to seal and pull to open. If repeated opening is important, define and test the required closure-cycle performance for the order.
- Best for: Products that need repeated access. Electronics components, small parts, food portions, travel kits.
- Advantages: Reusable, no sealing equipment needed, liquid-tight option available.
- Considerations: Higher cost than flat bags. Zipper adds thickness at the seal area.
- Price range: quoted by specification.
Self-Adhesive Bag -The No-Equipment Option
Self-adhesive bags (also called peel-and-seal bags) have a strip of adhesive covered by release paper. Peel the paper, fold the flap, press -sealed. No heat, no zipper.
Two sub-types exist: peel-and-seal (adhesive strip on flap) and fold-over flap (tuck-in closure without adhesive).
- Best for: Documents, small accessories, jewelry, samples, lightweight e-commerce items.
- Advantages: Manual seal only -no equipment needed. Clean, professional look.
- Considerations: Adhesive performance varies with temperature. Not suitable for heavy items.
- Price range: quoted by specification.
Quick Decision Flowchart
Need the bag to be resealable?
→YES: Zip lock bag (repeated access) or self-adhesive (single reseal)
→NO: Flat bag (lowest cost)
Have a heat sealer on hand?
→YES: Flat bag -fastest and cheapest
→NO: Self-adhesive (peel-and-seal) or zip lock
Selling to end customers directly?
→Zip lock or self-adhesive: better perceived value
→Flat bag if it's inside another package (e.g., garment box)
Quotation Comparison Table
| Bag Type | Quotation Basis | Relative Cost | Typical Use |
|---|---|---|---|
| Flat Bag | Quote by spec | Cost-efficient | Bulk packaging, garments |
| Self-Adhesive | Quote by spec | Mid | Documents, retail items |
| Zip Lock | Quote by spec | Higher | Small parts and repeat-access packaging |
Need a written quote for a specific size and quantity? Use our RFQ Specification Builder to prepare the details for review, then contact us.
Not Sure Which Bag Type Is Right for You?
Tell us what you're packaging and we'll recommend the option that fits that application.
Discuss Your Application →