# Weights and Measures Act 1985, Metric units


Tonne, metric tonne =
1000 kilograms.
KILOGRAM
for which the symbol “kg” is used, is the SI unit of mass, defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 x 10-34 when expressed in the unit J s, which is equal to kg m2 s-1, 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.
Hectogram =
1/10 kilogram.
Gram =
1/1000 kilogram.
Carat (metric) =
1/5 gram.
Milligram =
1/1000 gram.

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