Weights and Measures Act 1985

SCHEDULE 1 Definitions of Units of Measurement

Sections 1(2), 8(1). Part I Measurement of Length Imperial units . . . | . . . . . . | . . . . . . | . . . . . . | . . . 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. Part II Measurement of Area Imperial units . . . | . . . . . . | . . . . . . | . . . Metric units Hectare = | 100 ares. Decare = | 10 ares. Are = | 100 square metres. SQUARE METRE= | a superficial area equal to that of a square each side of which measures one metre. Square decimetre = | 1/100 square metre. Square centimetre = | 1/100 square decimetre. Square millimetre = | 1/100 square centimetre. Part III Measurement of Volume Metric units CUBIC METRE = | a volume equal to that of a cube each edge of which measures one metre. Cubic decimetre = | 1/1000 cubic metre. Cubic centimetre = | 1/1000 cubic decimetre. Hectolitre = | 100 litres. LITRE = | a cubic decimetre. Decilitre = | 1/10 litre. Centilitre = | 1/100 litre. Millilitre = | 1/1000 litre. Part IV Measurement of Capacity Imperial unit . . . | . . . . . . | . . . Pint = | 0.568 261 25 cubic decimetre. . . . | . . . . . . | . . . Metric units Hectolitre = | 100 litres. LITRE = | a cubic decimetre. Decilitre = | 1/10 litre. Centilitre = | 1/100 litre. Millilitre = | 1/1000 litre. Part V Measurement of Mass or Weight Imperial unit . . . | . . . . . . | . . . OUNCE TROY= | 0.031 103 476 8 kilogram. 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. PART VI Definitions of certain units which may not be used for trade except as supplementary indications Measurement of length Mile | = | 1760 yards. Furlong | = | 220 yards. Chain | = | 22 yards. YARD | = | 0.9144 metre. Foot | = | 1/3 yard. Inch | = | 1/36 yard. Measurement of area Square mile | = | 640 acres. Acre | = | 4840 square yards. Rood | = | 1210 square yards. Square yard | = | a superficial area equal to that of a square each side of which measures one yard. Square foot | = | 1/9 square yard. Square inch | = | 1/144 square foot. Measurement of volume Cubic yard | = | a volume equal to that of a cube each edge of which measures one yard. Cubic foot | = | 1/27 cubic yard. Cubic inch | = | 1/1728 cubic foot. Measurement of capacity Bushel | = | 8 gallons. Peck | = | 2 gallons GALLON | = | 4.54609 cubic decimetres. Quart | = | ¼ gallon. Gill | = | ¼ pint. Fluid ounce | = | 1/20 pint. Fluid drachm | = | 1/8 fluid ounce. Minim | = | 1/60 fluid drachm. Measurement of mass or weight Ton | = | 2240 pounds. Hundredweight | = | 112 pounds. Cental | = | 100 pounds. Quarter | = | 28 pounds. Stone | = | 14 pounds. POUND | = | 0.453 592 37 kilogram. Ounce | = | 1/16 pound Dram | = | 1/16 ounce. Grain | = | 1/7000 pound. Pennyweight | = | 24 grains. Ounce apothecaries | = | 480 grains. Drachm | = | 1/8 ounce apothecaries. Scruple | = | 1/3 drachm. Metric ton | = | 1000 kilograms. Quintal | = | 100 kilograms. Part VII Measurement of Electricity 1. | (a) AMPERE | for which the symbol “A” is used, is the SI unit of electric current, defined by taking the fixed numerical value of the elementary charge e to be 1.602 176 634 × 10-¹⁹ when expressed in the unit C, which is equal to A 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. (b) OHM | is the electric resistance between two points of a conductor when a constant potential difference of 1 volt, applied between the two points, produces in the conductor a current of 1 ampere, the conductor not being the seat of any electromotive force. (c) VOLT | is the difference of electric potential between two points of a conducting wire carrying a constant current of 1 ampere when the power dissipated between these points is equal to 1 watt. (d) WATT | is the power which in one second gives rise to energy of 1 joule , where the second has the meaning given in the definition of “AMPERE”. 2. | Kilowatt | = 1000 watts. Megawatt | = one million watts.