Micrometers to millimeters
1 micrometer = 0.001 millimeters
Type a value in micrometers (µm) to get millimeters (mm) straight away. A micrometer is smaller than a millimeter, so the number goes down. Both units belong to length, measured here against the meter.
1 µm = 0.001 mm
Formula
mm = µm × 0.001
One micrometer is 0.001 millimeters, so multiply by that factor. You can also divide by 1,000, the number of micrometers in one millimeter. Here µm is the value in micrometers and mm is the result in millimeters.
Worked example: 50 micrometers × 0.001 = 0.05 millimeters.
Micrometers to millimeters table
| micrometers (µm) | millimeters (mm) |
|---|---|
| 1 µm | 0.001 mm |
| 2 µm | 0.002 mm |
| 3 µm | 0.003 mm |
| 4 µm | 0.004 mm |
| 5 µm | 0.005 mm |
| 6 µm | 0.006 mm |
| 7 µm | 0.007 mm |
| 8 µm | 0.008 mm |
| 9 µm | 0.009 mm |
| 10 µm | 0.01 mm |
| 15 µm | 0.015 mm |
| 20 µm | 0.02 mm |
| 25 µm | 0.025 mm |
| 30 µm | 0.03 mm |
| 40 µm | 0.04 mm |
| 50 µm | 0.05 mm |
| 60 µm | 0.06 mm |
| 75 µm | 0.075 mm |
| 100 µm | 0.1 mm |
Everyday micrometers in millimeters
| What it is | µm | mm |
|---|---|---|
| PM2.5 particle size | 2.5 µm | 0.0025 mm |
| a red blood cell (about) | 7 µm | 0.007 mm |
| PM10 particle size | 10 µm | 0.01 mm |
| a human hair (about) | 70 µm | 0.07 mm |
| the thickness of paper (about) | 100 µm | 0.1 mm |
Quick estimate in your head
Divide by 10^3: move the decimal point 3 places left.
About the units
Micrometer (µm). One millionth of a meter, also called a micron. Used for hair width, filters and machining tolerances.
Millimeter (mm). One thousandth of a meter. Used for engineering drawings, rainfall and screen sizes in some countries.
Going the other way, 1 millimeter is 1,000 micrometers.
Questions
How many millimeters are in 1 micrometer?
1 micrometer is 0.001 millimeters, and 1 millimeter is 1,000 micrometers.
How do I convert micrometers to millimeters?
Use mm = µm × 0.001. For example, 50 micrometers × 0.001 = 0.05 millimeters.
Is the micrometer to millimeter factor exact?
The factor comes from the unit definitions. Results here are rounded to 6 significant digits for display.
How much is the thickness of paper in millimeters?
100 µm is 0.1 mm.
Source for the conversion factor: NIST SP 811, Appendix B (conversion factors).
Related conversions
- millimeters to micrometers
- centimeters to millimeters
- millimeters to centimeters
- millimeters to inches
- inches to millimeters
- millimeters to meters