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Millimeters to Micrometers (mm to μm)

Convert millimeters to micrometers: 1 mm = 1000 μm. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

Formula

1 mm = 1000 μm

micrometers = millimeters × 1000 — reverse: millimeters = micrometers × 0.001

The factor is derived from the SI definitions of both units (base unit: m) as listed in NIST SP 811; results on this page are shown to 6 significant figures, the API returns up to 12.

Worked examples

Millimeters to micrometers conversion table

Millimeters (mm)Micrometers (μm)
11000
22000
33000
44000
55000
66000
77000
88000
99000
1010000
1515000
2020000
2525000
3030000
4040000
5050000
7575000
100100000
200200000
250250000
500500000
10001000000

FAQ

How many micrometers are in one millimeter?

1 mm = 1000 μm. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

What is the formula to convert millimeters to micrometers?

Multiply the value in millimeters by 1000: micrometers = millimeters × 1000. For example, 5 mm = 5000 μm.

How do I convert micrometers back to millimeters?

Multiply by the inverse factor 0.001 (millimeters = micrometers × 0.001), or use the micrometers-to-millimeters page.

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