Reasons why Britain should complete metrication

Britain has made significant steps towards adopting the metric system but has not completed the changeover. Metric units are used almost universally in manufacturing, are commonplace in the retail sector, but are barely visible on Britain's roads and in some of the news media. Some key reasons to complete the adoption of the metric system include:

  1. We need a single system that everybody understands and uses
  2. The metric system is simply a better system of units than imperial
  3. Consumer protection
  4. Metric is international
  5. Helps the public understand health and safety
  6. Supports education especially calculation and numeracy skills

For a more detailed discussion see our Why metric? section.

We need a single system that everybody understands and uses

Every country needs a system of weights and measures. What we don’t need is two incompatible systems, with some people using one system and other people using a different system. This leads to incomprehension, conversion errors, accidents and additional costs.

Metric is simply a better system of units than imperial

Common sense would suggest that Britain should make use of the best system of units available. The metric system is better than imperial so therefore it makes sense to complete the conversion to metric as soon as possible.

The metric system is a consistent and coherent system of units. In other words, it fits together very well and calculations are easy because it is decimal. This is a big advantage for use in the home, education, industry and science.

Comparing metric with imperial

Metric Imperial
It is consistently based on decimal numbers It uses different number systems (base 3, 8, 12, 14, 16, etc)
Works well with percentages Percentages are difficult to work out (Try deducting 10% from your body weight in stones and pounds!)
Able to deal with very large and very small quantities (using prefixes based on powers of ten) Large units limited in size and have an awkward relationship to smaller units. Small quantities handled with awkward fractions

One sort of unit for weight:

  • gram (and its muliples)

Two systems of weight:

  • avoirdupois pounds, ounces, etc
  • troy pounds, ounces, etc

One system of volume:

1000 millilitres = 1 litre,
1000 litres = 1 cubic metre

Two systems of volume:

  • fluid ounces, pints, quarts, gallons
  • cubic inches, feet and yards

(How many pints in a cubic foot?)

Handles mechanical and electrical quantities No electrical units. Mixing imperial mechanical units and metric electrical ones is messy
Units are the same internationally

Some units differ between UK and US

  • different pints and gallons
  • different tons
  • different fluid and dry ounces
Simple calculations such as floor area, energy consumption and volumes are easy Simple calculations such as floor area, energy consumption and volumes are needlessly complicated

Consumer protection

In 1971, Britain made the switch from Roman-style currency (pounds, shillings and pence - £.s.d.) to decimal currency. Although many pundits predicted that the changeover would be a disaster, it was a major success. Two key reasons for this success were: firstly that the Government provided lots of useful information both in the run-up to the changeover and during the changeover period; secondly the old coinage was rapidly withdrawn from circulation thereby helping the public confront change as soon as possible.

Britain's metric conversion, in contrast, has failed to follow these critical success factors. There has been negligible and poor information provided to the public in order to prepare for change and old units have been left in circulation. Indeed although labelling and measurement in metric has been compulsory since 2000, supplementary labels in imperial have been allowed indefinitely subject to a review in 2019.

The result is a disaster for the consumer. Many retailers price only in imperial (an illegal practice) and some advertise prominently with imperial prices. Shoppers are frequently unable to compare the prices of similar products without using a calculator to convert imperial into metric.

Worse still, if a customer notes an imperial price in a supermarket, they cannot check whether they have been correctly charged at the checkout.

Imperial price label How does the customer know if the advertised price matches the price actually charged at the checkout? Check out receipt

Britain's slow changeover from imperial to metric has opened the door to practices that undermine the consumer. The consumer will benefit if the changeover is completed sooner rather than later.

(See more about this issue in our shopping section.)

Metric is international

During the second half of the twentieth century most countries that had previously used traditional units adopted metric. Japan abandoned traditional units in 1955 and India started to adopt metric in the late1950s. With Britain announcing its plans to go metric in 1965, the rest of the Commonwealth from Australia to Zambia made plans for a metric conversion (if they did not already have plans underway). Even the USA has made a start on metrication

The metric system is important for British trade and therefore also for British jobs. 88% of Britain's trade is with metric countries.

Pie chart

Source: extracted from Monthly Trade Statistics, March 2004.

Use of a common system of units facilitates cross-border collaboration in design, engineering, science and medicine.

The further development of the metric system is international. The development of the metric system is governed by the Metre Convention; which Britain signed in 1884. British scientists have contributed to the development of the metric system in the past and continue to do so.

Helps the public understand heath and safety

A good grasp of measurement units such as temperature, mass and distance is fundamental to health and safety. Britain's muddled mix of metric and imperial hinders the public's understanding of health and safety issues.

There is currently great public concern about the growth of obesity in Britain. The medical profession uses body mass index (BMI), calculated from an individual's mass in kilograms and height in metres, to assess whether a person has a healthy figure. People who measure themselves in metric can quickly assess whether their BMI is healthy or not. People who weigh themselves in stones and pounds and measure their height in feet and inches face a more complex calculation.

There are concerns today about the amount of salt and sugar people consume. Food contents are labelled by the number of grams of ingredient per 100 grams of product. People who measure food in pounds and ounces can only track their salt and sugar content with extra calculation.

Many drugs require a dosage based on a patient's body mass. The dosage of the drug is usually specified in milligrams of drug per kilogram of body mass. If patients give their weight in stones and pounds, healthcare professionals have to convert to kilograms to work out the correct dosage.

Health and safety regulations in the workplace are metric. Yet both the Government and the news media usually communicate with the public using imperial. This undermines public understanding of rules designed to protect them.

Conversions can also impact on safety. A brain surgeon piloting a private aircraft in Shoreham ran out of fuel and crashed on a house because he had incorrectly converted the capacity of his US-made fuel tanks from US gallons to litres and had not bought sufficient fuel (see the news report on the BBC website).

Many Britons like to walk in mountains, moors or coast paths for recreation. If they are lost in fog they risk falling off a precipice or into a bog. Thus good navigation is essential for safety. Britain's Ordnance Survey maps - used by walkers - are based on a kilometre grid. Thus understanding distances in metric is essential for outdoor safety. For more information, read an article from one of Scotland's best-known mountaineers.

maps1.gifMacdonalds distance sign

However, Department for Transport's traffic sign regulations forbid the use of metres for indicating distances. Ironically, metre-based signage is commonplace in the private sector.

Completing the metric conversion would help the British public to understand their medical records, observe health and safety regulations and enjoy the great outdoors safely.

Supports education especially numeracy and calculation skills

All political parties in Britain pay lip service to improving education standards in Britain. Concerns have been expressed about numeracy standards and the inability of one in three adults to perform basic practical calculations like area. Attaining proficiency in numeracy depends on the consistency between decimal numbers, decimal currency and the metric system of measurement. The continued use of imperial measures undermines and disrupts that essential base by constantly giving children and adults confusing mixed messages on measurement.

This schizophrenic approach means that the world of calculation is divorced from everyday life. Children therefore fail to apply their numeracy skills in their day-to-day experience. The workforce of the future needs to have sound skills in decimal calculation and measurement.

Completing the metric conversion in Britain would assist the improvement of mathematical skills by providing an environment that constantly reinforces what is taught in the classroom.

For more information read the views of an educational advisor.