# Weights and Measures Act 1985, Metric units


Kilometre =
1000 metres.
METRE
for which the symbol “m” is used, is the SI unit of length, defined by taking the fixed numerical value of the speed of light in vacuum c to be 299 792 458 when expressed in the unit m/s, where the second is defined by taking the fixed numerical value of the caesium frequency ΔvCs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s-1.
Decimetre =
1/10 metre.
Centimetre =
1/100 metre.
Millimetre =
1/1000 metre.

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Source: https://www.legislation.gov.uk/ukpga/1985/72/schedule/1/part/I/crossheading/metric-units (the official version)
Page: https://openlegislation.uk/weights-and-measures-act-1985/schedule-1/part-I/crossheading-metric-units
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.