Micrometers to Millimeters
Convert micrometers to millimeters instantly. 1 µm = 0.001 mm. Includes the exact factor, a conversion table of common values and the definition of both units.
How to convert micrometers to millimeters
To convert micrometers to millimeters, divide by 1,000 (multiply by 0.001). The relationship is fixed, so the same factor works for any quantity — there is nothing to look up and nothing that changes with temperature, location or context.
mm = µm × 0.001
Micrometers to Millimeters conversion table
The values people look up most often, rounded for reading. Use the calculator above for anything in between.
| Micrometers | Millimeters |
|---|---|
| 1 µm | 0.001 mm |
| 2 µm | 0.002 mm |
| 3 µm | 0.003 mm |
| 5 µm | 0.005 mm |
| 10 µm | 0.01 mm |
| 20 µm | 0.02 mm |
| 25 µm | 0.025 mm |
| 50 µm | 0.05 mm |
| 100 µm | 0.1 mm |
| 500 µm | 0.5 mm |
| 1,000 µm | 1 mm |
What is a micrometer?
A millionth of a metre, also called a micron. Human hair is roughly 70 µm across.
What is a millimeter?
A thousandth of a metre. The default fine unit on metric engineering drawings.
The formula
mm = µm × 0.001
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Micrometers to Millimeters
- Type the number of micrometers you want to convert.
- Read the result in millimeters straight away — there is no button to press.
- Check the table below for the values that come up most often, or reverse the conversion with the linked millimeters to micrometers page.
Micrometers to Millimeters — frequently asked questions
How many millimeters are in a micrometer?
One micrometer equals 0.001 mm. mm = µm × 0.001
What is the formula to convert micrometers to millimeters?
The formula is mm = µm × 0.001. It is an exact definition rather than an approximation, so the conversion never drifts no matter how large the number.
How do I convert millimeters back to micrometers?
Divide instead of multiplying: one millimeter is 1,000 µm. The reverse converter is linked in the related tools list.
Is this conversion exact?
Yes. Both units are defined against the same base unit by international agreement, so the factor is exact — any rounding you see is only in the display, which you can widen by entering more decimal places.
Is this micrometers to millimeters free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
What people search for
This page answers each of these searches. They are the exact phrases visitors use to find the micrometers to millimeters.
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About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 15, 2026 · Calculation runs client-side · No data collected · Report an error