Millimeters to micrometers
1 millimeter = 1,000 micrometers
Type a value in millimeters (mm) to get micrometers (µm) straight away. A millimeter is larger than a micrometer, so the number goes up. Both units belong to length, measured here against the meter.
1 mm = 1,000 µm
Formula
µm = mm × 1,000
One millimeter is 1,000 micrometers, so multiply the millimeter value by that factor. Here mm is the value in millimeters and µm is the result in micrometers.
Worked example: 250 millimeters × 1,000 = 250,000 micrometers.
Millimeters to micrometers table
| millimeters (mm) | micrometers (µm) |
|---|---|
| 1 mm | 1,000 µm |
| 2 mm | 2,000 µm |
| 3 mm | 3,000 µm |
| 4 mm | 4,000 µm |
| 5 mm | 5,000 µm |
| 6 mm | 6,000 µm |
| 7 mm | 7,000 µm |
| 8 mm | 8,000 µm |
| 9 mm | 9,000 µm |
| 10 mm | 10,000 µm |
| 15 mm | 15,000 µm |
| 20 mm | 20,000 µm |
| 25 mm | 25,000 µm |
| 30 mm | 30,000 µm |
| 40 mm | 40,000 µm |
| 50 mm | 50,000 µm |
| 60 mm | 60,000 µm |
| 75 mm | 75,000 µm |
| 100 mm | 100,000 µm |
Everyday millimeters in micrometers
| What it is | mm | µm |
|---|---|---|
| a sheet of paper (about) | 0.1 mm | 100 µm |
| a standard pencil lead | 2 mm | 2,000 µm |
| a 8 mm drill bit | 8 mm | 8,000 µm |
| the short side of an A4 sheet | 210 mm | 210,000 µm |
| the long side of an A4 sheet | 297 mm | 297,000 µm |
Quick estimate in your head
Multiply by 10^3: move the decimal point 3 places right (add 3 zeros).
About the units
Millimeter (mm). One thousandth of a meter. Used for engineering drawings, rainfall and screen sizes in some countries.
Micrometer (µm). One millionth of a meter, also called a micron. Used for hair width, filters and machining tolerances.
Going the other way, 1 micrometer is 0.001 millimeters.
Questions
How many micrometers are in 1 millimeter?
1 millimeter is 1,000 micrometers, and 1 micrometer is 0.001 millimeters.
How do I convert millimeters to micrometers?
Use µm = mm × 1,000. For example, 250 millimeters × 1,000 = 250,000 micrometers.
Is the millimeter to micrometer factor exact?
The factor comes from the unit definitions. Results here are rounded to 6 significant digits for display.
How much is the long side of an A4 sheet in micrometers?
297 mm is 297,000 µm.
Source for the conversion factor: NIST SP 811, Appendix B (conversion factors).
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