Weights and Measures Acts are acts of the Parliament of the United Kingdom determining the regulation of weights and measures. It also refers to similar statutes of the kingdoms of England and Scotland and the medieval Welsh states. The earliest of these were originally untitled but were given descriptive glosses or titles based upon the monarch under whose reign they were promulgated. Several omnibus modern acts have the short title "Weights and Measures Act" and are distinguished by the year of their enactment.

Background There have been many laws concerned with weights and measures in the United Kingdom or parts of it over the last 1,000 or so years. The acts may catalogue lawful weights and measures, prescribe the mechanism for inspection and enforcement of the use of such weights and measures and may set out circumstances under which they may be amended. Modern legislation may, in addition to specific requirements, set out circumstances under which the incumbent minister may amend the legislation by means of statutory instruments. Prior to the Weights and Measures Act 1985, weights and measures acts were only concerned with trade law where the weight or size of the goods being traded was important. The 1985 act, however, had a broader scope, encompassing all aspects covered by the European Economic Community (EEC) European Commission directive 80/181/EEC.

, the current primary legislation in the United Kingdom is the 1985 act, which was last amended by statutory instrument in 2025. Statutory instruments made under the authority of the act do not amend the act , but regulate particular areas covered by the act.

The act is currently enforced by the 200 Trading Standards offices managed by local authorities around the country. Definitions of units of measurements and the technical equipment relating to weights and measures are provided by the National Measurement Office, an agency of the Department for Business, Innovation and Skills.

Statute measure Historically, many units had various customary definitions—by locality or trade, for example. Where these units also had a standard, legally defined definition, such as given in a weights and measures act, this was known as the statute measure. So a land area might be given as 24 acres—statute measure, to clarify that it was the acre defined in statute, rather than a customary acre of a different size, that was being used. Units that had statute-defined measures as well as customary measures were the acre, mile, perch, pole and ton. The level of legal enforcement of statute measures achieved between the mid nineteenth and the beginning of the twentieth centuries meant that only "statute mile" and "statute ton" needed qualifying beyond then. The statute mile still needed to be differentiated from the nautical mile, but the others, and the term "statute measure" itself, are now only used in a historical context.

Metric units of measure

The Weights and Measures (Metric System) Act 1897 (60 & 61 Vict. c. 46) provided that metric units could be used in addition to the traditional imperial units for purposes of trade. In practice, the actual choice of units was restricted by price marking orders which listed packaging sizes and pricing structures that might be used in specific circumstances. For example, as of April 2012, wine for consumption on premises may only be sold in 125, 175, and 250 mL glasses while draught beer may only be sold as , , or pint and integer multiples of pint. Prior to 1973, when the United Kingdom joined the EEC, such specifications were almost all in imperial units.

As part of its attempt to harmonise units of measure between the member states of its Internal Market, the European Commission (EC) issued directive 80/181/EEC which set out the units of measure that should be used for what it called "economic, public health, public safety, and administrative" purposes. To comply with this directive, the Weights and Measures Act 1985 extended the scope of Trading Standards responsibilities from just matters related to trade to all aspects of the directive. For example, it was the Trading Standards Office that criticised the use of sub-standard weighing machines in NHS hospitals.

To help ease the EC's desired transition from sole use of imperial units to sole use of metric units, the directive permitted the use of what were termed "supplementary indicators"—the continued use of imperial units alongside the metric units catalogued by the directive (dual labelling). The initial intention was to prohibit dual labelling after the end of 1989, with metric units only being allowed after that date. This deadline was later extended: first to the end of 1999, then to the end of 2009. Finally, in 2007, the European Union (EU, as it had become) and the EC confirmed that the UK would be permitted to continue indefinitely to use imperial units such as pints, miles, pounds and ounces as at present. The Gloucestershire County Council Trading Standards Department confirmed the EU ruling that the previous deadline for ending dual labelling had been abolished.

There are still a few cases where imperial units are required to be used and where metric units are not permitted within the scope of the Weights and Measures Act, such as the pint for the sale of draught beer and cider, and miles and yards for distances on road signage. Milk in returnable containers may be sold by the pint and the troy ounce may be used for the sale of precious metals. In addition, British law specifies which non-metric units may be used with dual labelling (for example the imperial gallon, but not the US gallon).

England

Acts of the Witenagemot

Numerous acts of the Saxon kings are known to have been lost. Those that have survived include:

10th century 2 Edgar c. 8 (sometime between 959 and 963):

The statute also survives in a few other Old English and Latin copies, some which omit mention of London and describe "the measure held at Winchester", an indication that a standard ell or yard was nominally in use:Thorpe (1840), p. 525.

John Quincy Adams's 1821 report on the history of English weights and measures notes of this act that "it was never observed".

Acts of the Royal Council

11th century 3 William I c. 7 (1068):

12th century 9 Richard I c. 27 (1197):

Acts of Parliament

Statutes of uncertain date

The statutes of uncertain date () are generally dated to the mid-to-late 13th century.

The Assize of Bread and Ale () Sometimes dated to 51 Henry III (1267–68). Statute I - Section III:

(The Statute concerning Bakers, et cetera)

Also known as the , ("The Composition of Weights"), ("Assize of Weights and Measures") or the Weights and Measures Act 1303. In the Latin and English text, "hundred" (and the Latin numeral ) is used for four separate concepts: the Germanic long hundred of 120, the short hundred of 100, several units of either value, and a separate unit (the hundredweight) of 108 pounds. The form in which it appears in Cotton Claudius D2 where it is dated to 31 Edw. I (1303) is:

Magna Carta Although signed in 1215, Magna Carta was not ratified by Parliament until 1225, by which time it had become substantially abridged. Chapter 35 of Magna Carta of 1215 (which dealt with weights and measures) became chapter 25 of Magna Carta of 1225.

14th century 14 Edw. 3 Stat. 1. c. 12 (1340)Ruffhead (1763a), p. 227.

18 Edw. 3 Stat. 2. c. 4 (1344)Ruffhead (1763a), p. 241.

25 Edw. 3 Stat. 5. c. 9 (1350)Ruffhead (1763a), p. 264.

25 Edw. 3 Stat. 5. c. 10 (1350)

27 Edw. 3 Stat. 2. c. 10 (1353)Ruffhead (1763a), p. 279.

A chapter of the Statute of the Staple that provides for justices to be appointed to hear charges of measuring fraud at the staple ports. Those found guilty were liable for quadruple damages and 2 years' imprisonment. 31 Edw. 3 Stat. 1. c. 2 (1357)Ruffhead (1763a), pp. 290–291.

4 Ric. 2. c. 1 (1380)Ruffhead (1763a), p. 348.

13 Ric. 2. Stat. 1. c. 9 (1389)Ruffhead (1763a), p. 387.

15 Ric. 2. c. 4. (1391)Ruffhead (1763a), p. 401.

16 Ric. 2. c. 3. (1392)Ruffhead (1763a), p. 405.

15th century

1 Hen. 5. c. 10 (1413),Ruffhead (1763a), p. 485. An Act concerning the true Measure of Corn.

2 Hen. 5. Stat. 2. c. 4 (1414)Ruffhead (1763a), p. 499.

First notice of troy weight in statute.

8 Hen. 6. c. 5 (1429)Ruffhead (1763a), pp. 542–544.

18 Hen. 6. c. 16 (1439)Ruffhead (1763a), p. 594.

18 Hen. 6. c. 17 (1439) Vessels of Wine, Oyl, and Honey, shall be gauged.

11 Hen. 7. c. 4 (1494). An Act for Weights and Measures.

12 Hen. 7. c. 5 (1496)Evans (1836), pp. 312–313. An Act for Weights and Measures.

16th century Verdict of the Pyx 18 Henry VIII (1527)

23 Hen. 8. c. 4 (1531) An Act that no Brewers of Beer or Ale shall make their Barrels, Kilderkins or Firkins within them, and how much the same Barrels, et cetera shall contain.

24 Hen. 8. c. 3 (1532)Pickering (1763d), p. 252. An Act for flesh to be sold by weight, and the prices limited.

24 Hen. 8. c. 4 (1532) An Act concerning sowing of Flax and Hemp.

5 & 6 Edw. 6. c. 6 (1552) An Act for the true making of Woolen Cloth.

4 & 5 Ph. & M. c. 5. par. IX (1557–58) An act touching the making of woolen clothes.

23 Eliz. 1. c. 8 (1581)Pickering (1763f), p. 342. An Act touching the true melting, making and working of Wax.

35 Eliz. 1. c. 6 (1593)Pickering (1763f), p. 433. An Act against converting of great Houses into several Tenements, and for Restraint of Inmates and Inclosures, in and near about the City of London and Westminster.

This is the codification and namesake of the statute mile.

35 Eliz. 1. c. 10. par. III (1593)Pickering (1763f), p. 444. An act for the reformation of sundry abuses in clothes, called Devonshire kersies or dozens, according to a proclamation of the thirty-fourth year of the reign of our sovereign lady the Queen that now is.

17th century

16 Cha. 1. c. 19 (1640) An Act for the better ordering and regulating of the Office of Clerk of the Market, allowed and confirmed by this Statutes; and for the Reformation of false Weights and Measures.

22 Cha. 2 c. 8 (1670) An Act for ascertaining the Measures of Corn and Salt. First mention of the Winchester bushel in statute.

22 & 23 Cha. 2. c. 12 (1670)Pickering (1763h), pp. 353–355. An additional Act for ascertaining the Measures of Corn and Salt. 8 & 9 Will. 3 c. 22. s. 9 (1696–7)

First definition of the Winchester bushel in statute (≈2,150.42 cubic inches).

18th century

11 Will. 3. c. 15 (1700). An Act for ascertaining the Measures for retailing Ale and Beer.

1 Ann. c. 9 (1701)Raithby (1811), p. 349. An Act to ascertain the Water Measure of Fruit.

Great Britain

Acts of Parliament

18th century

(6 Ann. c. 27)Raithby (1811), p. 607. An Act for continuing several Subsidies, Impositions and Duties and for making Provisions therein mentioned to raise Money by Way of Loan for the Service of the War, and other Her Majesty's necessary and important Occasions, and for ascertaining the Wine Measure.

This statute is the origin of the US gallon, also known as the Queen Anne Gallon, Queen Anne Wine Gallon, or pre-1824 British gallon.

(10 Geo. 3. c. 44). An Act for more effectually preventing Traders in exciseable Commodities from using false Weights and Scales and for explaining and amending several Acts of Parliament relating to Hackney Coaches and Chairs.

(35 Geo. 3. c. 102) An Act for the more effectual Prevention of the Use of defective Weights, and of false and unequal Balances.

(37 Geo. 3. c. 143) An Act to explain and amend an Act made in the thirty-fifth Year of the Reign of his present Majesty, intituled, An Act for the more effectual Prevention of the use of defective Weights, and of false and unequal Balances.

19th century

(55 Geo. 3. c. 43)Evans (1836), pp. 325–327. An Act for the more effectual Prevention of the Use of false and deficient Measures.

(5 Geo. 4. c. 74). (The date of coming into effect was 1 May 1825).