Length and Area
miltomm
Convert mils (mil) to millimetres (mm).
Factor1 mil = 0.0254 mm
Converter
mil
Accepts numbers or expressions, e.g. 150 + 14.7
Result
mm
Rendered to 6 significant figures.
Formula
Formula
mm = mil × 0.0254
Multiply any value in mils by 0.0254 to obtain the value in millimetres.
Worked example
Convert 100 mil to mm.
- 01Start with 100 mil.
- 02Multiply by the conversion factor: 100 × 0.0254 = 2.54 mm.
Result100 mil = 2.54 mm
Conversion table
| mil | mm |
|---|---|
| 1 | 0.0254 |
| 2 | 0.0508 |
| 5 | 0.127 |
| 10 | 0.254 |
| 20 | 0.508 |
| 50 | 1.27 |
| 100 | 2.54 |
| 200 | 5.08 |
| 500 | 12.7 |
| 1000 | 25.4 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from mil to mm?
1 mil equals 0.0254 mm. To convert, multiply the value in mils by 0.0254.
How do I convert 1 mil to mm?
1 mil = 0.0254 mm. For any value, multiply by 0.0254.
How do I convert mm back to mil?
Divide by the same factor — or equivalently, multiply by 39.37008. So 1 mm = 39.3701 mil.
When would I need to convert mil (thousandth of an inch) to millimetre?
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).