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How to Choose Size, Mil Thickness, and Closure Type of Zip Locking Plastic Bags

NOV 04, 2022 • BY JEREMY •

At International Plastics we offer thousands of different combinations of plastic bags ranging in size, thickness, and closure type, it can get overwhelming. Below we will walk you through the steps of determining what size and mil bag you need based on your application or use to make the process simple. 

Plastic Bag Size Considerations

First, determine the size of your content. Usable space inside a ClearZip is measured side to side for the width. The length is from the zipper track to the bottom of the bag. To fit larger, rigid items through the opening, add half an inch to the width of your content.

If it is a slider lock, add one and a half inches.  For bulky items or a loose fit, add up to two inches to both dimensions. Plastic bag thickness is expressed in mils. A consumer-brand sandwich bag is about 1.5 mils thick.

Plastic Bag Closure Types

International Plastics offers multiple closure types depending on what you're sealing and how often you need to access the contents. 


Slider lock bags have a mechanism that seals the bag without having to pinch the closure together. This makes it easier to seal while wearing latex gloves or for children and the elderly. Slider locking bags are most useful in situations where the bag needs to be constantly opened and closed, saving time. 

Sliderlock Ziplock Bags

Double Track Ziplock Bags

Double-track ziplock bags are the same as regular ziplock bags with an additional seal. The additional track helps provide added protection for holding things such as liquids or contents likely to leak. 

Doubletrack Ziplock Bag

Ziplock Bags

Zip locking bags are the most common resealable bag style. Their pinch-to-seal zip lock provides a tight seal that can be opened and closed thousands of times. We offer a range of thicknesses to stand up to whatever you need to store from 1.25 mil lightweight bags for sandwiches to 8 mil industrial strength bags that can hold screws or sharp objects without puncturing. 

Ziplock Bag Holding Candy

Whichever Clearzip bags you choose, be assured, that they are made with virgin low-density polyethylene, 100% Recyclable, BPA-free, and meet all FDA/USDA requirements for food contact. Choose flexible packaging from International Plastics, with over half a century of proven experience and unsurpassed customer care. 


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