METRICATION: 100% complete
Metric Non-metric
All British Standards in metric terms.
Industrial training in metric.
Design in metric.
Production in metric.
Products and materials in metric.

In 1965, the Government announced its full support for the metrication of British industry:

“… the Government consider it desirable that British industries on a broadening front should adopt metric units sector by sector, until that system can become in time the primary system of weights and measures for the country as a whole … The Government hope that within ten years the greater part of the country’s industry will have effected the change …”

Douglas Jay – 24 May 1965

Even before 1965, British industry had already begun the switch to metric production. Export markets required metric-sized products, and the UK was already playing a part as a member of the International Standards Organisation (ISO) in the development of international standards for many engineering products.

The UK had played an active role in the development of the International System of Units (SI) itself, the modern iteration of the metric system which was approved by Conférence Générale des Poids et Mesures in 1960. Six SI units are named after British scientists and engineers.

The British Standards Institution (BSI) lead the way with the publication of new metric standards for industry, and the updating of existing British Standards with metric specifications. By 1971, 1200 British Standards had been re-drafted in metric terms.

Throughout the 1960s, The BSI worked with the International Standards Organisation (ISO) on the development of new international standards. In industry, it was never going to be enough to be merely using the same measurement system as the rest of the world, to facilitate international trade it was also important that countries adopted common standards.

For example in 1963, the BSI issued BS 3643 to incorporate the ISO recommendations that had been agreed up to that date on ISO metric screw threads. (see p78 BSI book)
In effect, international standard metric threads were now the British Standard for threads on screws, nuts, bolts and fastenings in general.

In March 1966, the BSI published Metric Standards for Engineering, a guide book for engineering firms planning the switch to British metric standards.

In July 1968, the BSI published, after widespread consultations through trade associations and in other ways, an agreed metrication programme and guide for the engineering industry. This set a target of 75% metric production by the end of 1975. However, progress was slower than planned, and the target was not met.

In April 1979, the main conclusions of a study meeting entitled Metrication – An Investment in Efficiency’, sponsored jointly by the Confederation of British Industry and the Metrication Board, were that:

  • There are no legislative barriers to the industry changing, but the agreed engineering target of 75%, metric production by end-1975 has not yet been reached;
  • some imperial production will be required for many years to provide spares and replacements for existing equipment;
  • prolonged general working in the two systems of measurement harms efficiency and imposes substantial cost penalties;
  • there is an urgent need to combine a programme of plant and equipment modernisation with metrication;
  • manufacturing, wholesaling and retailing have to move together in the change; and,
  • there is a clear need for a more positive commitment to metrication by Government.

The Metrication Board reported that leaders in the engineering industry attached importance to the early completion of the metric programme throughout the economy as a whole.
Metrication in industry could not easily be completed in isolation from the rest of society. The rate of progress was greatly affected by progress in other sectors, especially retail trade. Industry leaders were of the opinion that the phasing out of imperial units for retail sales would quickly bring about the use of metric units in everyday life and powerfully influence the changeover in industry.

Until metric production was the norm, for all but spares and replacements for existing equipment, companies would continue to compete at a disadvantage with overseas suppliers.

Many reported extra costs in working to dual standards, double stock holding, conversion problems and waste due to errors and scrap on the shop floor. The President of the Institute of Purchasing and Supply estimated that fastener manufacturers and stockists alone had £40 million tied up in dual stocks.

In June 1979, the Director General of the Confederation of British Industry (CBI), while recognising that industry itself had a part to play in bringing about the completion of metrication in the economy as a whole, commented, ‘there’s no room for two measurement systems in an efficient trading nation – one for the housewife and one for the businessman … at the moment we are in the worst of both worlds’.

In 1980, the Metrication Board collaborated with a firm of management consultants in a survey to try to quantify the costs of:

  • changing to metric, and
  • working in imperial as well as metric.

Over 800 firms have taken part in the survey. Preliminary analysis of the replies indicated that:

  • over 50% of production was still in imperial;
  • the costs of dual working are nearly 3% of the annual value of home sales;
  • and the capital costs of metricating could be recovered in less than two years.

Industry metrication leaflet – 1968

Industrial metrication programmes

Industrial metrication programmes leaflet – 1970

General programmes

1969 1970 1971 1972 1973 1974 1975
Construction industry
Metric standards
Metric products & materials
Metric design
Metric construction
Electrical industry
Metric standards
Metric products & materials
Metric design
Metric production
Marine industry
Metric standards
Metric products & materials
Metric design
Metric construction
Engineering industries
Metric standards
Metric products & materials
Metric design
Metric production
1969 1970 1971 1972 1973 1974 1975

Announced programmes for products and materials

1969 1970 1971 1972
Aluminium: castings
Aluminium: foil
Aluminium: wrought
Ball and roller bearings
Board: insulating
Board: paper
Board: pasted display and showcard
Board: printing
Boxes: crates etc.
Boxes: metal
Building blocks
Cellulose film
Chemicals general: in all trade in the U.K.
Chemicals general: intrade between member firms
Concrete pipes
Copper and copper alloy : wire rod, sheet, strip, etc.
Expanded polystyrene board
Fibre board packing cases
Glass: flat
Hides and skins: unprocessed
Paper: blotting
Paper: book printing
Paper: cover
Paper: machine glazed for envelopes and posters
Paper: manilla
Paper: printing and writing
Paper: speciality coated
Paper: waterproof
Paper: wrapping
Paving flags
Photographic equipment
Photographic materials
Pitch fibre pipes
Plywood: home produced
Plywood: imported
Polythene: film
Polypropylene: film
PVC: calendered rigid
PVC: extruded film
Ready-mixed concrete
Roofing felt
Sand and gravel
Scientific and industrial instruments
Steel bars and mesh for concrete reinforcement
Stone and chalk
Synthetic rubber
Textile fibres for commercial users : wool, cotton, jute, synthetic
Timber: home grown
Timber: imported
Windows: aluminium
Windows: steel
Wire: insulated
Wood pulp
1969 1970 1971 1972
Build up.
A planned changeover period during which both current imperial and new metric sizes/quantities should be available. Subsequently, only metric sizes/ quantities will be available as standard.
A changeover period has been recommended but the precise timing and duration will be decided by individual companies.
The industry is planning to go metric on a particular date and no prolonged changeover period is foreseen.