Millimeter to Mil Formula
mil = mm x 39.3701
Conversion factors follow SI relationships published by BIPM and NIST, where those standards apply.
Millimeter to Mil Converter
Quick Answer
1 mm = 39.3701 mil
Formula: Mil = Millimeter x 39.3701
Quick values
Worked examples
Convert 1 mm to mil
mil = 1 x 39.3701
Result: 1 mm = 39.3701 mil
Convert 10 mm to mil
mil = 10 x 39.3701
Result: 10 mm = 393.701 mil
Convert 100 mm to mil
mil = 100 x 39.3701
Result: 100 mm = 3937.01 mil
About Millimeter and Mil
Divide millimeters by 0.0254, or multiply by 39.3701, to get mils (thousandths of an inch, also called thou). 1 mm = 39.3701 mil. Use this when a metric thickness must match a US PCB or coating callout.
Category hub: Length Conversion · Conversion charts · Conversion formulas
Millimeter to Mil Conversion Table
| Millimeter (mm) | Mil (mil) |
|---|---|
| 0.025 mm | 0.984252 mil |
| 0.05 mm | 1.9685 mil |
| 0.1 mm | 3.93701 mil |
| 0.25 mm | 9.84252 mil |
| 0.5 mm | 19.685 mil |
| 1 mm | 39.3701 mil |
| 2 mm | 78.7402 mil |
| 5 mm | 196.85 mil |
| 10 mm | 393.701 mil |
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Practical use cases for Millimeter to Mil
Metric drawings on US lines
A 0.2 mm plating or adhesive callout is 7.87 mil. US inspectors still write acceptance in mils or thou.
Sheet-metal and shim stock
Metric shim kits in 0.05 mm steps convert to about 2 mil steps so they match US feeler-gauge language.
Medical balloon and film
Device specs mix mm wall thickness with mil-based US supplier lots. Incoming inspection converts before lot release.
Conformal coating
IPC metric thickness bands in mm are compared to US process windows in mils. The factor is 39.37 mil per millimeter.
Millimeter to Mil FAQs
Common questions about converting millimeter to mil.
How do you convert millimeters to mils?
Multiply millimeters by 39.3701. Example: 1 mm = 39.370 mil, 0.1 mm = 3.937 mil, 0.035 mm ≈ 1.378 mil (1 oz copper is often quoted near 1.4 mil).
What is 2 mm in mils?
2 × 39.3701 = 78.740 mil. That is about 0.0787 inch.
Should I use mil or thou on a US drawing?
Both mean 0.001 in. Electronics usually says mil; machine shops often say thou. The number is identical.
Is this the same as millimeters to inches?
No. Mils are thousandths of an inch. 1 mm = 0.03937 in = 39.37 mil. Use the inch converters when the drawing dimension is in inches, not mils.
Charts and printable PDF
Browse the conversion-chart library for printable millimeter / mil tables. PDF files are linked only when a matching download already exists.
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