Length and Area
μmtomil
Convert micrometres (μm) to mils (mil).
Factor1 μm = 0.03937008 mil
Converter
μm
Accepts numbers or expressions, e.g. 150 + 14.7
Result
mil
Rendered to 6 significant figures.
Formula
Formula
mil = μm × 0.03937008
Multiply any value in micrometres by 0.03937008 to obtain the value in mils.
Worked example
Convert 100 μm to mil.
- 01Start with 100 μm.
- 02Multiply by the conversion factor: 100 × 0.03937008 = 3.93701 mil.
Result100 μm = 3.93701 mil
Conversion table
| μm | mil |
|---|---|
| 1 | 0.03937 |
| 2 | 0.07874 |
| 5 | 0.19685 |
| 10 | 0.3937 |
| 20 | 0.7874 |
| 50 | 1.9685 |
| 100 | 3.937 |
| 200 | 7.874 |
| 500 | 19.685 |
| 1000 | 39.37 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from μm to mil?
1 μm equals 0.03937008 mil. To convert, multiply the value in micrometres by 0.03937008.
How do I convert 1 μm to mil?
1 μm = 0.0393701 mil. For any value, multiply by 0.03937008.
How do I convert mil back to μm?
Divide by the same factor — or equivalently, multiply by 25.4. So 1 mil = 25.4 μm.
When would I need to convert micrometre to mil (thousandth of an inch)?
Length conversions appear in piping, layout, and mechanical drawings — particularly when reconciling imperial fittings or instrument lengths with metric plant drawings.
Is the conversion exact?
The factor shown is precise to at least 7 significant figures. For most process-engineering work this is far better than instrument accuracy. For metrology or trade applications, refer to the relevant national standard (NIST, BIPM, ISO 80000).