A mil is one thousandth of an inch, and on a trash bag it measures the thickness of the plastic film. The number shows up on contractor bags, where it is the main claim: Hefty states 2 mil for its standard contractor bags and 3 mil for its Load & Carry contractor line. It did not show up on the same brand’s large-capacity household bags, whose pages state capacity and strength in words rather than a thickness figure. So the mil number is useful for comparing heavy-duty bags to each other, and often absent for the bag a household actually rebuys.
The unit, and the easy mistake
A mil is 0.001 inch. It is the unit Hefty uses for film thickness on its contractor bags, and it is not a millimeter. A millimeter is about 39 mils, so a bag described as 3 mil is a little under a tenth of a millimeter thick. When you see the two side by side on a package or a listing, the spelling is the tell. “Mil” is the thousandth of an inch. “Mm” is the metric unit, and it is far too large a figure for any trash bag.
Where manufacturers state it
Hefty’s own pages give two figures. Its Contractor Bags page describes them as “2 mil thick industrial trash bags” and says they are made “from construction sites to home improvement projects.” Its Load & Carry Contractor Bags page describes “extra thick, 3 mil construction and extra long flap ties,” with built-in handles for hanging the bag while loading.
That is one manufacturer, two products, and a one-mil difference between them, stated in the manufacturer’s own words. Both are sold for project debris rather than kitchen waste. That is the context the number lives in.
Where they don’t
We read the same brand’s pages for its Strong and Ultra Strong large trash bags. Neither states a mil figure. They describe gallon capacity and strength in words instead. That absence is a real finding. A kitchen bag without a stated thickness has not told you how thick it is, and no amount of reading the front of the box changes that. Runlow’s product records for kitchen bags work the same way. Where a manufacturer states a fact, it renders. Where it doesn’t, the record says so rather than filling the gap.
How to use the number when it’s there
Mil thickness answers one question: how much plastic is in the wall of the bag. It says nothing about the seam, the drawstring, or the resin, and a brand’s claims about tear resistance or stretch are separate claims that sit beside the mil figure rather than following from it. For two contractor bags with stated thicknesses, the higher number is more film. Whether that is worth paying for depends on what is going in. The manufacturer pages that state the figure describe the job as construction debris and cleanup, which is the case thickness was made for.
For the kitchen, the questions that actually decide the purchase are capacity, closure, and odor control, and those are what our guides rank on. See Best Tall Kitchen Trash Bags and Best Trash Bags for Odor Control. To work out how many bags a year your can size and household actually run through, our trash bags calculator does that math.
Where this comes from
Both mil figures above are quoted from Hefty’s own product pages, linked in the text. The statement that the brand’s kitchen and large-capacity pages carry no mil figure is what we found on the pages we read on the date this post was last checked. The definition of a mil is a unit conversion, not a product claim. Runlow has not tested any trash bag for thickness or strength.
Frequently asked questions
- What is a mil?
- One thousandth of an inch. It is a unit of film thickness, not a millimeter. A 3 mil bag is 0.003 inches thick. The two units are easy to confuse on a package, and the difference is a factor of about 25.
- Do kitchen trash bags list a mil figure?
- The Hefty large-capacity household bag pages we read do not state one. The figure appeared only on the brand's contractor bags, where thickness is the selling point. A bag with no mil figure has not told you how thick it is, and this post doesn't guess.
- Is a thicker bag always the better buy?
- Not for every job. The manufacturer pages that state a mil figure describe those bags as made for construction debris and project cleanups. A thicker film costs more per bag, and a kitchen can that holds food scraps and packaging is a different job from one holding drywall.
