Millimetre online conversion form



The millimetre (international spelling as used by the International Bureau of Weights and Measures; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length. Therefore, there are one thousand millimetres in a metre. There are ten millimetres in a centimetre.

One millimetre is equal to¬†1000¬†micrometres¬†or¬†1000000¬†nanometres. Since an¬†inch¬†is officially defined as exactly 25.4 millimetres, a millimetre is therfore equal to exactly ‚Äč5‚ĀĄ127¬†(‚Čą 0.03937) of an inch.

Convert Millimeter to Centimetre

1 mm = 0.1 cm
1 cm = 10 mm

Example: convert 10 mm to cm:
10 mm = 10 √ó 0.1 cm = 1 cm

Millimetre to Centimetre Calculator online

Ruler with millimetre and centimetre marks
General information
Unit system SI derived unit
Unit of Length
Symbol mm
Named after The¬†metric prefix¬†mille¬†(Latin¬†for “one thousand”) and the¬†metre
1 mm in … … is equal to …
¬†¬†¬†micrometres ¬†¬†¬†1√ó103¬†őľm¬†= 1000¬†őľm
¬†¬†¬†centimetres ¬†¬†¬†1√ó10‚ąí1¬†cm¬†= 0.1¬†cm
¬†¬†¬†metres ¬†¬†¬†1√ó10‚ąí3¬†m¬†= 0.001¬†m
¬†¬†¬†kilometres ¬†¬†¬†1√ó10‚ąí6¬†km
   inches    0.039370 in
   feet    0.0032808 ft



  1. Definition
  2. Informal terminology
  3. Unicode symbols
  4. Measurement
  5. References

1.  Definition 

Since 1983, the¬†metre¬†has been defined as “the length of the path travelled by¬†light¬†in¬†vacuum¬†during a time interval of¬†1/299792458¬†of a¬†second”.[1]¬†A millimetre,¬†1/1000¬†of a metre, is therefore the distance travelled by light in¬†1/299792458000¬†of a second.

2. Informal terminology 

A common shortening of millimetre in spoken English is “mil”. This can cause confusion since in the United States, “mil” traditionally means a¬†thousandth of an inch.

3. Unicode symbols 

For the purposes of compatibility with Chinese, Japanese and Korean (CJK) characters, Unicode has symbols for:

  • millimetre („éú) – code U+339C[2]
  • square millimetre („éü) – code U+339F[2]
  • cubic millimetre („é£) – code U+33A3[2]

In Japanese typography, these square symbols were historically used for laying out unit symbols without distorting the grid layout of text characters.

4. Measurement 

On a metric ruler, the smallest measurements are normally millimetres.[3] High-quality engineering rules may be graduated in increments of 0.5 mm. Digital callipers are commonly capable of reading increments as small as 0.01 mm.[4]

Microwaves with a frequency of 300 GHz have a wavelength of 1 mm. Using wavelengths between 30 GHz and 300 GHz for data transmission, in contrast to the 300 MHz to 3 GHz normally used in mobile devices, has the potential to allow data transfer rates of 10 gigabits per second.[5]

The smallest distances the human eye can resolve is around 0.02 to 0.04 mm, approximately the width of a human hair.[6] A sheet of paper is typically between 0.07 mm and 0.18 mm thick, with ordinary printer paper or copy paper approximately a tenth of a millimetre thick.[7]

5. References 

  1. ¬†“17th General Conference on Weights and Measures (1983), Resolution 1”. International Bureau of Weights and Measures. Retrieved¬†3 December¬†2013.
  2. ¬†“CJK Compatibility”(PDF). Retrieved¬†3 December¬†2013.
  3. ¬†“How do I read a ruler?”. Retrieved¬†3 December¬†2013.
  4. ¬†“Accuracy of Calipers”. Retrieved¬†3 December¬†2013.
  5.  Huang, Kao-Cheng; Wang, Zhaocheng (2011). Millimeter Wave Communication Systems. ISBN9781118102756.
  6. ¬†“How Small Can the Naked Eye See?”. Focus Magazine. Retrieved¬†3 December¬†2013.
  7. ¬†“Thickness of a Piece of Paper”. Archived from¬†the original¬†on 8 June 2017. Retrieved¬†3 December¬†2013

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