Length and Area
miltoμm
Convert mils (mil) to micrometres (μm).
Factor1 mil = 25.4 μm
Converter
mil
Accepts numbers or expressions, e.g. 150 + 14.7
Result
μm
Rendered to 6 significant figures.
Formula
Formula
μm = mil × 25.4
Multiply any value in mils by 25.4 to obtain the value in micrometres.
Worked example
Convert 1 mil to μm.
- 01Start with 1 mil.
- 02Multiply by the conversion factor: 1 × 25.4 = 25.4 μm.
Result1 mil = 25.4 μm
Conversion table
| mil | μm |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 5 | 127 |
| 10 | 254 |
| 20 | 508 |
| 50 | 1270 |
| 100 | 2540 |
| 200 | 5080 |
| 500 | 12700 |
| 1000 | 25400 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from mil to μm?
1 mil equals 25.4 μm. To convert, multiply the value in mils by 25.4.
How do I convert 1 mil to μm?
1 mil = 25.4 μm. For any value, multiply by 25.4.
How do I convert μm back to mil?
Divide by the same factor — or equivalently, multiply by 0.03937008. So 1 μm = 0.0393701 mil.
When would I need to convert mil (thousandth of an inch) to micrometre?
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).