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Film Gauge Conversion Chart

A posting chart that converts plastic film thickness between gauge, mil, inch and micron for stretch film, poly bags and liners.

Ref PK-0203ASTM D6988

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

Plastic film thickness is stated in four common units. Gauge is used mostly for stretch film. Mil is one-thousandth of an inch and is used for poly bags, sheeting and low-density can liners. Micron (µm) is one-thousandth of a millimeter and is used for high-density liners and international specs. The units convert exactly: 100 gauge = 1 mil = 0.001 in = 25.4 µm. ASTM D6988 covers how film thickness is measured.

How to read it

Find the known value in its column.
Read across the row for the other units.
For values not listed: mil = gauge ÷ 100; micron = mil × 25.4; mil = micron ÷ 25.4.

Conversion chart

Gauge	Mil	Inch	Micron (µm)
40	0.40	0.0004	10.2
47	0.47	0.00047	11.9
50	0.50	0.0005	12.7
60	0.60	0.0006	15.2
63	0.63	0.00063	16.0
70	0.70	0.0007	17.8
75	0.75	0.00075	19.1
80	0.80	0.0008	20.3
90	0.90	0.0009	22.9
100	1.0	0.001	25.4
120	1.2	0.0012	30.5
150	1.5	0.0015	38.1
200	2.0	0.002	50.8
300	3.0	0.003	76.2
400	4.0	0.004	101.6
600	6.0	0.006	152.4

Key points

Thickness alone does not set strength. Resin type, layer structure and additives matter as much.
Some stretch films are sold by "equivalent" or "performance" gauge. That is a performance claim, not the true thickness. Ask for the true gauge when comparing.
High-density liners are much thinner than low-density liners of similar strength. Do not compare them by thickness.
Thin films are hard to measure with a hand micrometer. Weight per area is often more reliable.
When downgauging, test on real loads and real wrapper settings.

Common mistakes

Confusing gauge with mil and ordering film 100 times too thick or too thin on paper.
Comparing an "equivalent 80 gauge" film to a true 80 gauge film on price alone.
Converting microns to mil with 25 instead of 25.4 on large orders.
Using the steel sheet "gauge" system, which is unrelated to film gauge.

Governing standards: ASTM D6988 (thickness of plastic film); ASTM D4649 (stretch wrap film selection).

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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