Convert Micrometre to Millimetre
1 micrometre = 0.001 millimetre (mm). For example, 10 micrometre = 0.01 millimetre and 100 micrometre = 0.1 millimetre. Type any value below to convert micrometre to millimetre both ways — it runs entirely in your browser.
Quick answer: Micrometre to Millimetre
1 Micrometre = 0.001 Millimetre (µm → mm). To convert micrometre to millimetre, multiply by 0.001. To convert millimetre to micrometre, multiply by 1,000. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common micrometre-to-millimetre questions.
How to convert Micrometre to Millimetre
To convert micrometre to millimetre, multiply the number of micrometre by the conversion factor 0.001, because 1 µm = 0.001 mm. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 mm = 1,000 µm, so you divide by 0.001 (or multiply by 1,000) to turn millimetre back into micrometre.
mm = µm × 0.001 ·
µm = mm × 1,000
- Write down the value you want to convert, in micrometre.
- Multiply it by 0.001.
- The result is the same area/length/quantity expressed in millimetre.
Micrometre to Millimetre — worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 micrometre is 0.005 millimetre because 5 µm × 0.001 = 0.005 mm.
| Micrometre | Calculation | Millimetre |
|---|---|---|
| 1 µm | 1 µm × 0.001 = 0.001 mm | 0.001 mm |
| 2 µm | 2 µm × 0.001 = 0.002 mm | 0.002 mm |
| 3 µm | 3 µm × 0.001 = 0.003 mm | 0.003 mm |
| 5 µm | 5 µm × 0.001 = 0.005 mm | 0.005 mm |
| 7 µm | 7 µm × 0.001 = 0.007 mm | 0.007 mm |
| 10 µm | 10 µm × 0.001 = 0.01 mm | 0.01 mm |
| 12 µm | 12 µm × 0.001 = 0.012 mm | 0.012 mm |
| 15 µm | 15 µm × 0.001 = 0.015 mm | 0.015 mm |
| 20 µm | 20 µm × 0.001 = 0.02 mm | 0.02 mm |
| 25 µm | 25 µm × 0.001 = 0.025 mm | 0.025 mm |
| 50 µm | 50 µm × 0.001 = 0.05 mm | 0.05 mm |
| 100 µm | 100 µm × 0.001 = 0.1 mm | 0.1 mm |
Common Micrometre to Millimetre conversions
These are the micrometre-to-millimetre values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 micrometre = 0.001 millimetre
- 2 micrometre = 0.002 millimetre
- 2.5 micrometre = 0.0025 millimetre
- 3 micrometre = 0.003 millimetre
- 4 micrometre = 0.004 millimetre
- 5 micrometre = 0.005 millimetre
- 6 micrometre = 0.006 millimetre
- 7 micrometre = 0.007 millimetre
- 8 micrometre = 0.008 millimetre
- 9 micrometre = 0.009 millimetre
- 10 micrometre = 0.01 millimetre
- 12 micrometre = 0.012 millimetre
- 15 micrometre = 0.015 millimetre
- 20 micrometre = 0.02 millimetre
- 25 micrometre = 0.025 millimetre
- 30 micrometre = 0.03 millimetre
- 50 micrometre = 0.05 millimetre
- 75 micrometre = 0.075 millimetre
- 100 micrometre = 0.1 millimetre
- 200 micrometre = 0.2 millimetre
- 500 micrometre = 0.5 millimetre
- 1000 micrometre = 1 millimetre
Micrometre to Millimetre conversion chart (both directions)
The chart below converts micrometre to millimetre and millimetre to micrometre side by side, so it works whichever way you need. 1 micrometre = 0.001 millimetre, and 1 millimetre = 1,000 micrometre.
| Micrometre → Millimetre | Millimetre → Micrometre |
|---|---|
| 0.25 µm = 0.00025 mm | 0.25 mm = 250 µm |
| 0.5 µm = 0.0005 mm | 0.5 mm = 500 µm |
| 1 µm = 0.001 mm | 1 mm = 1,000 µm |
| 2 µm = 0.002 mm | 2 mm = 2,000 µm |
| 3 µm = 0.003 mm | 3 mm = 3,000 µm |
| 4 µm = 0.004 mm | 4 mm = 4,000 µm |
| 5 µm = 0.005 mm | 5 mm = 5,000 µm |
| 6 µm = 0.006 mm | 6 mm = 6,000 µm |
| 7 µm = 0.007 mm | 7 mm = 7,000 µm |
| 8 µm = 0.008 mm | 8 mm = 8,000 µm |
| 9 µm = 0.009 mm | 9 mm = 9,000 µm |
| 10 µm = 0.01 mm | 10 mm = 10,000 µm |
| 12 µm = 0.012 mm | 12 mm = 12,000 µm |
| 15 µm = 0.015 mm | 15 mm = 15,000 µm |
| 20 µm = 0.02 mm | 20 mm = 20,000 µm |
| 25 µm = 0.025 mm | 25 mm = 25,000 µm |
| 30 µm = 0.03 mm | 30 mm = 30,000 µm |
| 40 µm = 0.04 mm | 40 mm = 40,000 µm |
| 50 µm = 0.05 mm | 50 mm = 50,000 µm |
| 75 µm = 0.075 mm | 75 mm = 75,000 µm |
| 100 µm = 0.1 mm | 100 mm = 100,000 µm |
| 150 µm = 0.15 mm | 150 mm = 150,000 µm |
| 200 µm = 0.2 mm | 200 mm = 200,000 µm |
| 250 µm = 0.25 mm | 250 mm = 250,000 µm |
| 500 µm = 0.5 mm | 500 mm = 500,000 µm |
| 1000 µm = 1 mm | 1000 mm = 1,000,000 µm |
Micrometre vs Millimetre: which is bigger?
A millimetre is the larger unit: one millimetre equals 1,000 micrometres. Put another way, you need 1,000 micrometres to make a single millimetre.
What is a Micrometre? History, origin and usage
The micrometre, one-millionth of a metre, was long called the 'micron', a name officially adopted by the international metrology body in 1879. In 1967 the SI formally replaced 'micron' with 'micrometre' so the standard micro- prefix (symbol µ) would be used consistently.
The micrometre measures things invisible to the naked eye: biological cells, bacteria, fibres and the wavelengths of infrared light. It is also common in optics and in fibre-optic and semiconductor engineering.
A human hair is roughly 50 to 100 micrometres across. Despite being officially deprecated, 'micron' survives in everyday industrial use, partly to avoid confusion with the micrometer measuring instrument.
What is a Millimetre? History, origin and usage
The millimetre is one-thousandth of a metre, taking its prefix from the Latin mille, 'thousand'. Like the other metric submultiples it dates to the French metric reform of the 1790s.
The millimetre is the workhorse of engineering drawings, machining and manufacturing, where tolerances are specified in millimetres or fractions of them. It is also the standard unit for rainfall and snowfall depth in meteorology.
Rainfall reported in 'millimetres' is the depth water would reach on a flat surface, so one millimetre of rain equals one litre per square metre. The smallest markings on most metric rulers are millimetres.
Convert 1 Micrometre to other units
It can help to see a micrometre next to the other units it is commonly compared with. One micrometre (µm) is equal to:
| 1 Micrometre equals | Unit |
|---|---|
| 0.000000001 km | Kilometre |
| 0.000001 m | Metre |
| 0.00001 dm | Decimetre |
| 0.0001 cm | Centimetre |
| 0.001 mm | Millimetre |
| 0.0000000006213712 mi | Mile |
| 0.000001093613 yd | Yard |
| 0.00000328084 ft | Foot |
| 0.00003937008 in | Inch |
| 0.0000000005399568 nmi | Nautical Mile |
| 0.00000000497097 fur | Furlong |
| 0.0000000497097 ch | Chain |
| 0.00000497097 li | Link |
| 0.0000001988388 rd | Rod |
| 0.0000001988388 pole | Pole |
| 0.0000005468066 ftm | Fathom |
| 0.00000984252 hand | Hand |
| 0.000004374453 span | Span |
| 0.000008748906 finger | Finger |
| 0.000002187227 cubit | Cubit |
| 0.000000164042 rope | Rope |
| 0.00000055 ken | Ken |
| 0.0000000002071237 lea | League |
| 0.002834646 pt | Point |
| 0.000000000000000006684587 AU | Astronomical Unit |
| 0.0000000000000000000001057001 ly | Light-year |
| 0.0000001 dam | Decametre |
| 0.00000001 hm | Hectometre |
| 0.0000000001799856 nl | Nautical League |
Convert 1 Millimetre to other units
One millimetre (mm) is equal to:
| 1 Millimetre equals | Unit |
|---|---|
| 0.000001 km | Kilometre |
| 0.001 m | Metre |
| 0.01 dm | Decimetre |
| 0.1 cm | Centimetre |
| 1,000 µm | Micrometre |
| 0.0000006213712 mi | Mile |
| 0.001093613 yd | Yard |
| 0.00328084 ft | Foot |
| 0.03937008 in | Inch |
| 0.0000005399568 nmi | Nautical Mile |
| 0.00000497097 fur | Furlong |
| 0.0000497097 ch | Chain |
| 0.00497097 li | Link |
| 0.0001988388 rd | Rod |
| 0.0001988388 pole | Pole |
| 0.0005468066 ftm | Fathom |
| 0.00984252 hand | Hand |
| 0.004374453 span | Span |
| 0.008748906 finger | Finger |
| 0.002187227 cubit | Cubit |
| 0.000164042 rope | Rope |
| 0.00055 ken | Ken |
| 0.0000002071237 lea | League |
| 2.834646 pt | Point |
| 0.000000000000006684587 AU | Astronomical Unit |
| 0.0000000000000000001057001 ly | Light-year |
| 0.0001 dam | Decametre |
| 0.00001 hm | Hectometre |
| 0.0000001799856 nl | Nautical League |
Tips for converting Micrometre to Millimetre
- To go from micrometre to millimetre, multiply by 0.001; to go back, divide by 0.001 (or multiply by 1,000).
- For a quick mental estimate, remember that 1 micrometre ≈ 0.001 millimetre, so 10 micrometre ≈ 0.01 millimetre.
- The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
- Both fields update live as you type — change either side to convert in that direction.
How to use this Micrometre to Millimetre converter
Type a number into the Micrometre field and the equivalent in Millimetre appears instantly — there is no “convert” button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the Millimetre field to convert the other way (millimetre to micrometre). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above — use the chart for quick look-ups and the tool for precise work.
Accuracy and method
Every figure on this page — the formula, the worked examples, the conversion chart and the “convert to other units” tables — is computed from a single verified conversion factor (1 µm = 0.001 mm), never copied from a hand-typed lookup table that could drift. That factor is derived from each unit’s definition in terms of a common base unit, and an automated check re-verifies all of the site’s factors on every update, so the numbers here stay correct over time. This matters for micrometre-to-millimetre conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.
Sources
- BIPM — The International System of Units (SI Brochure) — the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.
- NIST — Definitions of the SI base units — the US National Institute of Standards and Technology reference for the SI base units, used here as an independent cross-check on the base-unit definition.
The metric units (km, m, cm, mm, µm) are exact by definition, and the imperial units (mile, yard, foot, inch, nautical mile) use their exact international values. Traditional units (hand, span, finger, cubit, rod/pole, link, rope, ken, league) are given at their commonly accepted standard sizes — historical local values sometimes differed, so confirm against a primary source before relying on them for legal or historical work.
Frequently asked questions
- How many millimetre are in 1 micrometre?
- 1 micrometre = 0.001 millimetre (mm). To convert any number of micrometre to millimetre, multiply by 0.001.
- How do I convert micrometre to millimetre?
- Multiply the number of micrometre by 0.001. For example, 10 micrometre = 10 × 0.001 = 0.01 millimetre, and 25 micrometre = 0.025 millimetre.
- How many micrometre are in 1 millimetre?
- 1 millimetre = 1,000 micrometre. So to convert millimetre back to micrometre, multiply by 1,000.
- What is the formula to convert micrometre to millimetre?
- millimetre = micrometre × 0.001. The reverse formula is micrometre = millimetre × 1,000.
- How much is 100 micrometre in millimetre?
- 100 micrometre = 0.1 millimetre. (And 1000 micrometre = 1 millimetre.)
- Which is bigger, a micrometre or a millimetre?
- A millimetre is larger: 1 millimetre = 1,000 micrometre.
- Is this micrometre to millimetre converter accurate?
- Yes — every value is computed from the exact 0.001 mm per µm factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert millimetre to micrometre too?
- Yes. The converter works both ways — enter a value in either field. 1 millimetre = 1,000 micrometre.