I edited a question and changed "mils" to "mm", though that may not have actually been the unit the author intended. Do we have a policy on this? All my metric friends say "mils" to refer to "mm", while American manufacturers say "mils" to mean thousandths of an inch. Modern engineers call this unit "thou", which in unambiguous.

Do we have a policy on not using ambiguous units, and if they should be changed to the more modern units when encountered? Also, I have no idea which unit was originally intended, as 2 mm plastic is really thick but 2 thou plastic is incredibly thin (as latex gloves are 5-8 thou).

1 Answer 1


You should post a comment asking the OP for clarification.

In this case '2 Mil' is probably the most correct term, plastic sheeting is sold and labeled with 'Mil' being the description. Google '2 mil plastic sheeting' and you find things like this with 2 Mil printed on the box.

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    This is the perfect answer. More information regarding the purpose of comments can be found here.
    – Mooseman
    Jul 15, 2019 at 16:38
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    I just checked Wikepedia, and for European engineers, "mils" means "mm". I find this rationale (the common usage of "mil" to describe plastic in the USA only) to be insufficient. Other parts of the site attempt to be multi-regional. I would expect that to apply to lifehacks as well. That would preclude using a unit that means something different in Europe. en.wikipedia.org/wiki/Thousandth_of_an_inch
    – piojo
    Jul 16, 2019 at 2:32

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