Convert micrometer to mm
Convert micrometer to mm instantly. 1 µm = 0.001 mm. Formula, worked examples and a quick reference table.
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One micrometer equals 0.001 millimeters. To convert any number of micrometers to millimeters, multiply by 0.001.
The converter above works in both directions and updates as you type. Below you will find the formula, a worked example and a reference table of common values.
Length conversions come up wherever a measurement crosses a border: a height given in feet and inches on a form that wants centimetres, a running distance recorded in kilometres and compared against miles, a component specified in millimetres and ordered from a supplier working in inches. The conversions themselves are exact — the inch, foot, yard and mile have all been defined in metric terms since 1959 — so any discrepancy comes from rounding, not from the units disagreeing.
micrometer to mm formula
To go the other way, use micrometer = millimeter ÷ 0.001.
About these units
The micrometre, or micron, is a millionth of a metre. It is the scale of bacteria, fine dust and semiconductor features, and the unit particulate air-quality limits are quoted in.
The millimetre is the working unit of engineering drawings and machining across most of the world, precise enough that dimensions rarely need decimals.
Micrometer is also written micrometre, micrometres, micrometers, micron, microns and um. Millimeter is also written millimetre, millimetres and millimeters.
Sources
micrometer to mm conversion table
| Micrometer | Millimeter |
|---|---|
| 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 |
| 250 µm | 0.25 mm |
| 500 µm | 0.5 mm |
| 1,000 µm | 1 mm |
Frequently asked questions
How many millimeters are in a micrometer? +
There are 0.001 millimeters in one micrometer.
What is 10 µm in mm? +
10 µm equals 0.01 mm. Multiply 10 by 0.001.
How do I convert millimeter back to micrometer? +
Use micrometer = millimeter ÷ 0.001. The converter above handles both directions, or see our dedicated mm to micrometer page.
How accurate is this micrometer to millimeter conversion? +
The factor used is 0.001, carried at full double precision. Where a unit has an exact legal definition the factor is exact rather than approximate. Rounding is applied only to the displayed result, so the answer is never a calculation done on an already-rounded number.
Is there a quick way to estimate µm to mm in my head? +
Divide by 1,000. That matches the true factor of 0.001 exactly, so no adjustment is needed for a mental estimate.