Myths about metric internationally

It is not uncommon that myths about metric usage abroad are used as justifications for keeping imperial in the UK.

Mythical octupus

On the continent, markets use imperial pounds.
In several languages a half kilogram is nicknamed a ‘pound’ however this still means they are using grams and kilograms. Read more

Even metric nations use non-metric units.
Non-metric units are used rarely in specialised sectors. Read more

The United States uses imperial units.
US customary measures overlap with imperial but are not identical. Read more

The United States does not use metric.
The US has made some limited progress in adopting metric. Read more

Other countries have not criminalised the use of imperial units.
It is normal for countries to have penalties for using non-legal units. This applies to imperial units where they are non-legal. Read more

On the continent, markets use imperial pounds

It has been noted that some markets on the Continent may have labels referring to ‘livre’ or ‘pond’ and it is implied that imperial pounds are being used there while being forbidden on UK weighing machines.

The truth is that when metric was adopted on the Continent expressions like ‘livre’ or ‘pond’ were used as colloquial expressions for half a kilogram. Weighing machines on markets use grams and kilograms and not imperial pounds.

It has been argued that these units are not permitted by the EC Directives. However, it is important to note that these terms do not have any legal standing. To argue against colloquial terms is like saying we should not use terms like ‘quid’, ‘bob’, ‘fiver’ (or ‘buck’ and ‘penny’ in the USA), because these have never been legal terms of currency.


Even metric nations use non-metric units

This is partly true and warrants closer examination. In many cases, it is the historical dominance of the USA in particular fields that has forced the rest of the world to fall into line. Examples are:

  • Computer screens labels (though European companies often include the centimetre size as well)
  • Guns & ammunition – obviously these have to be mutually compatible, and some imperial calibres become self-perpetuating
  • Car wheels – the past dominance of the US car industry
  • Plumbing fixtures – a few European countries use inch-based parts
  • Aircaft heights and speeds, engine thrusts in pounds force – US industry dominance again


The United States uses imperial units

Many people believe that imperial units in Britain are the same as US customary units. This is only partially true and there are some key areas where imperial and customary units differ:

Imperial Customary
1 fluid ounce = 28.415 mL 1 fluid ounce = 29.575 mL
1 pint = 20 fluid ounces 1 pint = 16 fluid ounces
1 gallon = 160 fluid ounces 1 gallon = 128 fluid ounces
1 hundredweight = 112 pounds 1 hundredweight = 100 pounds
1 ton = 2240 pounds 1 ton = 2000 pounds

Note also that the imperial gallon, hundredweight and ton are no longer in use in the UK.

Note also that the United States has two variations of the foot – the international foot and survey foot which differ very slightly. Also the ‘stone’ as a unit of weight is not known in the US.


The United States does not use metric

Although the USA has made only erratic progress towards metrication (like the UK), it has nonetheless advanced. Its wine and spirits industry made the change back in the 1970s, the car industry went metric in the mid-1980s (with considerable savings), and many goods are appearing in shops in rational metric sizes. Dual-labelling of goods is now mandatory for most products. The semiconductor industry is metric, and U.S. Government programs, such as NASA, are required to use the International System of Units for measurement “except where impractical”. The Apollo Guidance Computer, onboard the Apollo 11 Lunar Module that landed on the Moon in 1969, used SI units for powered-flight navigation and guidance calculations.

The US is ahead of the UK in one significant area: that of road signs. They repealed the legislation which forbade metric units on signs over a decade ago and authorise metric distances and speed limits as alternatives. For more detail on practical examples of the changes happening in the USA, see Jim Frysinger’s Metric Methods site.


Other countries have not criminalised the use of imperial units

It is up to individual nations how transgressions of national laws are penalised. In the EU, Directives were established to harmonise units of measurements across the member states in order to facilitate trade. The actual legislation to enact these requirements is the responsibility of each member state, as are the penalties for breaches.

The penalties within the UK have not changed substantially since the 1963 Weights & Measures Act, and the most severe are reserved for offenders who persistently give misleading information. All that has changed is the list of permitted units. So someone persistently advertising by the bushel or peck could have been fined after 1968, even before the 1995 metrication legislation was enacted.

Further afield, in New Zealand, breach of the regulations can result in a fine of up to NZ$5000.