Convert Millimeters to Micrometers
1 millimeter is 1,000 µm. One millimeter is exactly 1000 micrometers.
One millimeter is 1000 micrometers. To convert millimeters to micrometers, multiply by 1000; to go the other way, divide by 1000 or multiply by 0.001. The factor is exact rather than rounded: it follows from NIST. One thousandth of a meter.
Factor checked against the defining standard · How we check
- Millimeters × 1000
1 * 10001,000 µm
1 millimeter in every length unit
| Unit | Value | Exact factor |
|---|---|---|
| inches | 0.03937007874 in | × 0.0393700787402 |
| feet | 0.003280839895 ft | × 0.00328083989501 |
| yards | 0.001093613298 yd | × 0.00109361329834 |
| miles | 0.0000006213711922 mi | × 0.000000621371192237 |
| millimeters (as entered) | 1 mm | — |
| decimetres | 0.01 dm | × 0.01 |
| centimeters | 0.1 cm | × 0.1 |
| meters | 0.001 m | × 0.001 |
| kilometers | 0.000001 km | × 0.000001 |
| nautical miles | 0.0000005399568035 nmi | × 0.000000539956803456 |
| micrometers | 1,000 µm | × 1,000 |
| nanometers | 1,000,000 nm | × 1,000,000 |
| thou | 39.37007874 thou | × 39.3700787402 |
Factors are entered by hand from NIST rather than derived from a units library, so the ones that terminate are exact rather than rounded.
The same converter answers this pair however it is written: millimetres to micrometres is the British spelling of the same units — the metre and the litre are spelled that way outside the United States and the quantity does not change.
How do you convert millimeters to micrometers? The converter and the working
- 1.Take the measurement in millimeters.
- 2.Multiply by 1000 — that is how many micrometers fit in one millimeter.
- 3.To go back the other way, divide by 1000, or multiply by 0.001.
Worked example: 25 millimeters to micrometers
- Formula
- mm × 1000 = µm
- Arithmetic
- 25 × 1000 = 25,000 µm
- Answer
- 25 mm = 25,000 µm
The factor is exact, so this figure is exact too — only the display is rounded.
Millimeters to micrometers conversion table
| Millimeters | Micrometers |
|---|---|
| 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 |
| 12 mm | 12,000 µm |
| 15 mm | 15,000 µm |
| 20 mm | 20,000 µm |
| 25 mm | 25,000 µm |
| 50 mm | 50,000 µm |
| 100 mm | 100,000 µm |
| 200 mm | 200,000 µm |
| 300 mm | 300,000 µm |
| 500 mm | 500,000 µm |
| 1000 mm | 1,000,000 µm |
| 2000 mm | 2,000,000 µm |
| 5000 mm | 5,000,000 µm |
| 10000 mm | 10,000,000 µm |
What is a millimeter?
One thousandth of a meter. The working unit of metric engineering drawings, which avoid decimals by using it throughout.
What is a micrometer?
A millionth of a meter, still widely called a micron. Machining tolerances, filter ratings and cell diameters are all quoted here.
How many micrometers are in a millimeter?
One millimeter is 1000 micrometers, exactly. Going the other way, one micrometer is 0.001 millimeters. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every length unit here
The whole group — 13 units with their symbols and the size of each one in meters — is on the conversion index, along with every pair it makes. The table above already gives each of them relative to a millimeter.
Source: NIST — international yard and pound agreement (inch = 25.4 mm exactly)
Cite this page
- APA
- Rule Calculator. (2026). Convert Millimeters to micrometers. Rule Calculator. https://rulecalculators.com/convert/millimeter-to-micrometer
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- Chicago
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Questions people actually ask
- How many micrometers are in a millimeter?
- 1000. A millionth of a meter, still widely called a micron. Machining tolerances, filter ratings and cell diameters are all quoted here.
- How do I convert micrometers back to millimeters?
- Divide by 1000, or multiply by 0.001 — they are the same operation.
Other length conversions
Micrometers to millimeters — the same conversion the other way.