Hello @infmswsr ,[br]
In general, guides can follow a few different formats. Guides written by our iFixit team should specify which units the screws are measured in. Within community written guides, things can be less clear. You could try commenting on a guide to find out this bit of information and hopefully the author replies to you in a timely manner.[br]
Using a digital caliper would be the most ''precise'' way to get a measurement, but any ruler with mm, cm, and inches will work, too![br]
I hope this answers your question, let me know if you have more!
