Film gauge is usually listed in either mils, microns, or gsm depending on the supplier, which makes comparing films across sources more confusing than it needs to be. Here's how these measurements relate to each other and how to convert between them.
Mils vs. Microns vs. Gauge
A mil is one-thousandth of an inch and is the most common unit used in the U.S. A micron is one-millionth of a meter, commonly used internationally. "Gauge" is an older unit sometimes still used informally, roughly equal to one-quarter of a micron.
Quick Conversion Reference
- 1 mil = 25.4 microns
- 1 micron = approximately 0.0394 mils
- 100 gauge ≈ 25 microns ≈ 1 mil
These conversions are useful when comparing spec sheets from suppliers who use different measurement standards, so you're comparing actual thickness rather than assuming units match.
Why This Matters When Comparing Films
A film listed as "75 gauge" and one listed as "0.75 mil" aren't the same thickness — getting the conversion wrong can lead to ordering film that's thinner or thicker than intended, affecting both cost and performance.
When in Doubt, Ask for Mils
If you're used to working in one unit, it's simplest to ask suppliers to quote in that unit directly rather than converting every spec sheet yourself.
Need Help Comparing Film Specs?
Our film selection guide covers gauge alongside other film specs, or contact our team if you're comparing options.
