What is a Mil?




Wikipedia defines a "Mil" as a thousandth of an inch which is equal to 0.001 inches. To get a real sense of how thin that really is take a look at these common everyday items -


  • Credit Cards - Most credit cards come in at 30 thousands of an inch or 30 mils
  • Razor Blade - The edge of a razor can range all the way from 3.93 mil to 15.7 mil
  • Hair - The human hair is 3 mils thick

The introduction of the thousandth of an inch or Mil as a sensible base unit in engineering and machining is generally attributed to Joseph Whitworth who wrote:

...instead of our engineers and machinists thinking in eighths, sixteenths and thirty-seconds of an inch, it is desirable that they should think and speak in tenths, hundredths, and thousandths...

Up until this era, workers such as millwrights, boilermakers, and machinists measured only in traditional fractions of an inch, divided as far as 64ths. As technology advanced and base materials became stronger and lighter the need for an exact way to measure very thin substrates was needed. Thus the Mil was born.


In the packaging world we use the term Mil to define the thickness of a wide variety of products including -

  • Tape
  • Stretch film
  • Poly Bag
  • Shrink & Vacuum Pouches

In laymen's terms the thicker the mil the thicker the product. For example your standard Ziploc® Brand sandwich bag is 1.5 Mil thick or ½ the thickness of a human hair. That is some pretty thin stuff protecting your food from leaking all over your fridge.



Now if you are in to math you can convert -



Mil to Inches by taking the (Mil / 1000 = Inches)






Or you can make life simple and use our Mil Conversion Chart



Into the following measurement:

Answer =