Convert Mils to Micrometers
1 mil equals 25.4 micrometers (µm).
1 mil = 25.4 µm
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk mil to micrometer converter to paste a column from Excel.
How to Convert Mil to Micrometer
- 1 mil = 25.4 µm
- 1 µm = 0.03937007874 mil
- Example: convert 15 mil to µm: 15 mil = 15 × 25.4 µm = 381 µm
Formula
µm = mil × 25.4
Derivation from SI units:
- 1 mil = 0.001 in = 25.4 µm (exact)
- 1 µm = 10⁻⁶ m
- 1 mil = 0.0000254 m ÷ 0.000001 m per µm = 25.4 µm
Both units are defined exactly, so the factor is exact. Mil definition: mil; Micrometer definition: micrometer.
Worked examples
- A reading of 4 mil converts to 101.6 µm.
4 mil × 25.4 = 101.6 µm - A value of 15 mil is 381 µm.
15 mil × 25.4 = 381 µm
Mil to Micrometer conversion table
| Mils (mil) | Micrometers (µm) |
|---|---|
| 0.5 mil | 12.7 µm |
| 1 mil | 25.4 µm |
| 1.5 mil | 38.1 µm |
| 2 mil | 50.8 µm |
| 3 mil | 76.2 µm |
| 4 mil | 101.6 µm |
| 5 mil | 127 µm |
| 6 mil | 152.4 µm |
| 8 mil | 203.2 µm |
| 10 mil | 254 µm |
| 15 mil | 381 µm |
| 20 mil | 508 µm |
| 40 mil | 1016 µm |
| 50 mil | 1270 µm |
| 100 mil | 2540 µm |
Where it's used
Mils are used for plastic film and bag thickness, while micrometers appear in particle and filter ratings (PM2.5, PM10, HEPA tested at 0.3 µm). Both measure length and distance, so the conversion is a fixed factor.
Mil to other length units
| Conversion | 1 mil equals |
|---|---|
| mil to meter | 0.0000254 m |
| mil to kilometer | 2.54 × 10⁻⁸ km |
| mil to centimeter | 0.00254 cm |
| mil to millimeter | 0.0254 mm |
| mil to micrometer | 25.4 µm |
| mil to nanometer | 25400 nm |
| mil to angstrom | 254000 Å |
| mil to mile | 1.578282828 × 10⁻⁸ mi |
| mil to yard | 0.00002777777778 yd |
| mil to foot | 0.00008333333333 ft |
| mil to inch | 0.001 in |
| mil to nautical mile | 1.371490281 × 10⁻⁸ nmi |
Frequently asked questions
How many micrometers are in 1 mil?
1 mil = 25.4 µm.
How do I convert mils to micrometers?
Multiply the value in mil by 25.4. For example, 15 mil × 25.4 = 381 µm.
Is the mil to µm conversion exact?
Yes. Both units are defined exactly, and 1 mil is exactly 25.4 µm.
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "mil (0.001 in)".
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Mils to Micrometers. Retrieved October 17, 2026, from https://scientificconverters.com/length/mils-to-micrometers/
IEEE
Scientific Converters, "Convert Mils to Micrometers," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/length/mils-to-micrometers/