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Bag Thickness Standards: What is a Mil?

Most bag bans regulate the thickness of bag materials in mils. The problem is: most of us don’t know what is a mil.  If you’re an engineer, you probably know what a mil is, but the rest of us need some help.

So, what is a mil? A mil is a thousandth of an inch. Generally, measurements of less than 1/8 of an inch are too small to see, but often we can feel them.

California has set the legal standard for a plastic film bag at 2.25 mil. Some cities allow bags a little thinner, and others require bags to be a little smaller, but more bans have this measurement than any other thickness.

Plastic fabric bags are not normally measured in mils but in GSM. Learn more about GSM here.  Only plastic film bags, made with plastic sheeting that does not breathe, is so thin that mils become an appropriate measurement. In California, the minimum weight for fabric bags is 80 GSM.

To give you a tactile sense of how measurements in mils can be useful, here are some ordinary objects and their measurement in mils.

Thickness Measured in Mils

Item Mils
A dime is 53 mils Dime 53
A credit card is 30 mils
Credit Card
NWPP bags are 20 mils
1BAG Standard Bag
10 pieces of paper are 10 mils
10 pieces of paper
thick plastic bag is 2.25 mils Thick plastic bag 2.5
thin plastic bags are .5 mils Thin Plastic Bag –BANNED by most bans .5

Bags of 2.25 mil are technically reusable, but few people reuse them. A study by Save our Shores surveyed shoppers in Monterey CA county, after a bag ban had been implemented. Out of the 740 shoppers questioned, only 4 had reused a bag of that thickness. Save our Shores and other groups are advocating that bags be at least 4 mils in order to be classified as reusable.

Bag bans are new and as more information comes in about how regulations affect consumers and stores, modifications are likely to be forthcoming. You can always call 1 Bag at a Time for a quote on our wholesale shopping bags and ask us to check your local bag laws to make sure our products are in compliance.