How this calculator works
One mil is one thousandth of an international inch. Since the inch is exactly 25.4 mm, one mil is exactly 0.0254 mm. This avoids confusing a mil with the much larger millimetre when reading industrial film or coating specifications.
Formula
mm = mils x 0.0254; mils = mm / 0.0254.
Worked example
A 6 mil sheet is exactly 0.1524 mm thick. A 0.5 mm sheet is about 19.68503937 mils.
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Frequently asked questions
How thick is 10 mil in millimetres?
Exactly 0.254 mm.
Are mil and thou interchangeable?
Yes, for a linear thickness both mean 0.001 inch.
Is the reverse result always a whole number?
No. A round metric size often corresponds to a fractional mil value.