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Metrication UK @metrication.uk · 28/08/2026

1980s/1990s-style #metrication ▶️ width ◀️ restriction signs, featuring separate roundels for 6'-6" and 2.0 m. Photographed in 2008, the signs have since been replaced with dual-unit signs. #metric @showmeasign.online metrication.uk/transport/ro...

Width restriction signs, photographed in 2008, featuring separate roundels for 6'-6" and 2.0 m.

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Metrication UK @metrication.uk · 13/08/2026

Dual units, with separate metric and imperial signs, paved the way for metric-only signs - imperial signs could be removed when all signs were dual units. However, in 1994, this #metrication route was scuppered, when the metric height roundel was withdrawn and a new dual unit sign was introduced.

On the left are two options for signing a height restriction in 1981 - imperial-only OR dual-unit (two separate signs)

On the right are two options for signing a height restriction in 1994 - imperial only OR dual-unit (metric and imperial on the sign)

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Metrication UK @metrication.uk · 13/08/2026

#OTD 45 years ago, #metric restriction signs 🚗 were introduced on 🇬🇧 UK roads. From 13 August 1981, metric units 📏 could be used for the first time, alongside imperial units, to indicate height, width and length restrictions on 🇬🇧 UK road signs. Weight restriction signs went metric on the same day.

An imperial width restriction sign indicating a width restriction of 6 feet 6 inches, together with an equivalent metric sign from 1981 showing a width restriction of 2.0 metres.

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Metrication UK @metrication.uk · 01/06/2026

Apart from medicines, which went metric in 1969, 🖌️ paint was the first liquid product to be sold to the public in metric volumes. #Metric cans of 🎨 paint first went on sale in June 1971. #metricsystem #metrication metrication.uk/industry/con...

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Metrication UK @metrication.uk · 15/02/2026

The musical film "Half a Sixpence" was released in 1967 - the same year in which the last pre-decimal coins 🪙 were minted. "Half of Two and a Half new pence" didn't have quite the same ring to it, but that didn't stop #decimalisation 55 years ago today. #OTD #OnThisDay #DecimalDay

2 decimal coins from 1971:

A 2 NEW PENCE coin, and a ½ NEW PENNY coin.

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Metrication UK @metrication.uk · 31/12/2025

56 years ago today was the last chance to use the HALF CROWN coin, before the switch to #decimal currency. There were four crowns to the pound, but crown coins weren't in general use. When learning about money, any child asking what it was worth would be told, "TWO AND SIX". #OTD #decimalisation

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Metrication UK @metrication.uk · 25/12/2025

🎄 🎅 Merry Christmas 🎁 🎄 A metric-size Robertson's Christmas Pudding 🥳 400 g METRIC PACK - circa 1980 #ChristmasPudding #metricpack #metrication #metric #metricsystem #Christmas

A Robertson's Christmas Pudding in its box

400 g METRIC PACK

circa 1980

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Metrication UK @metrication.uk · 10/12/2025

Here's a 1973 edition of the leaflet ... #GoingMetric

GOING
METRIC

Check List
for
Managers

MM1
August 1973

Metrication Board

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Metrication UK @metrication.uk · 23/11/2025

On this day 60 years ago, the British standard for screw threads 🔩 went #metric. On 23 November 1965, major sectors of British industry approved a BSI policy statement urging British firms to make ISO metric threads their first choice for all future designs. #OTD #metricsystem #metrication #ISO

a cross section diagram of an ISO metric screw thread

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Metrication UK @metrication.uk · 01/11/2025

On this day 50 years ago, breakfast cereals went #metric. On 1 November 1975, METRIC PACK sizes ⚖️ were introduced for flaked breakfast cereals 🌽❄️. Imperial pack sizes were withdrawn on 30 June 1978. #OTD #metricsystem #metrication

A 1975 METRIC PACK of Kellogg's Corn Flakes.

The back of the pack includes information about the switch to metric pack sizes:

"Kellogg's and Metrication

You will probably have noticed from the front of this packet that it has a new metric weight. It now contains 500 grammes (1.10 lb) of Corn Flakes in place of the previous 16 oz.

Since the Weights and Measures Act, 1963, we have had to pack our flaked breakfast cereals in multiples of 4 ounces. This was the main reason why Corn Flakes were packed in 8 oz, 12 oz and 16 oz packet sizes.

But now that Britain is changing to the metric weight system the Law has been amended to permit flaked cereals to be packed and sold in set metric quantities.

This Giant pack, which previously held 16 ounces, will now contain 500 grammes (one of the new set quantities). So there are now 10% more Corn Flakes in the packet."

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Metrication UK @metrication.uk · 01/10/2025

For 50 years now, the familiarity of the 1 kg bag of sugar has made it easy to visualise body weight ⚖️ changes in kilograms To visualise weight changes in stones 🪨, we have ... oh! The sale of #METRIC PACKs of sugar was first permitted 50 years ago today, on 1 October 1975 #thinkmetric #OTD #KISS

A 1976 Silver Spoon 1 kilogram METRIC PACK of sugar

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Metrication UK @metrication.uk · 29/09/2025

No 50th anniversary special #stamps from the Post Office today, but here's an event day cover ✉️, from 50 years ago, commemorating the Post Office's 🏤 very own M-Day.

A British stamps "Day of Event" Cover, commemorating the #metrication of the Post Office #metrication on 29 September 1975.

The envelope bears the words, "THE POST OFFICE GOES METRIC".
The 8½p stamp is franked with the words, "NATIONAL POSTAL MUSEUM 29 SEP 1975 LONDON EC1".

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Metrication UK @metrication.uk · 29/09/2025

#OTD On this day, 50 years ago, the Post Office 🏤 went #metric 📏. On 29 September 1975, all ⚖️ weight-based 📮📦 postal tariffs switched to the #metric system. POSTER: "Mail goes metric from 29 Sept" metrication.uk/post-office/

A 1975 Post Office poster titled, "Mail goes metric from 29 Sept".

Some examples of the new weight steps

INLAND
letters
60g 100g 150g 200g 250g 300g 350g 400g 450g 500g 750g

parcels
1kg 2kg 3kg 4kg 5kg 6kg 7kg 8kg 9kg 10kg

OVERSEAS
air-letters - Europe
20g 50g 100g

air-letters - Outside Europe
15g 30g 40g

Imperial equivalents for the new weight values are given in brackets.

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Metrication UK @metrication.uk · 21/09/2025

That diagram misses out cubic inches and cubic feet. Here's an amended one, plus the equivalent in #metric ...

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Metrication UK @metrication.uk · 06/09/2025

2025 is the 50th anniversary of Rugby's switch to the #metric system for all measurements. In 1975, the 25-yard line became the 22-metre line, and the crossbar height was set at 3.0 metres. passport.world.rugby/laws-of-the-...

A diagram of a Rugby Union pitch showing all dimensions in round metric values. It includes the 22-metre and 10-metre lines.

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Metrication UK @metrication.uk · 17/08/2025

METRIC PACKS of Homepride flour in the "Homepride Selection" catalogue leaflet, 1979 bsky.app/profile/oldu...

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Metrication UK @metrication.uk · 17/08/2025

Sugar in 1 kg METRIC PACKS first appeared in the shops 49 years ago, in the summer of 1976: bsky.app/profile/oldu...

A 1 kilogram METRIC PACK of sugar - 1976

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Metrication UK @metrication.uk · 16/08/2025

This is the leaflet mentioned in the advert: metrication.uk/shopping/foo...

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Metrication UK @metrication.uk · 13/08/2025

At that time, metric restriction signs could only be used in combination with, and positioned below, an equivalent imperial sign. 44 years later, despite dual-unit signs being compulsory on all new signs installed since 2016, imperial-only signs are still in use.

Road sign diagrams from the TSRGD 1981.

Diagram 530
Headroom at hazard.
Permitted variant: Metric units may be substituted for imperial units within the warning triangle.

Diagram 629
Vehicles exceeding width indicated prohibited.
Permitted variant:
Metric units may be substituted for imperial units within the warning triangle.

#metrication #roadsigns

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Metrication UK @metrication.uk · 13/08/2025

#OTD 44 years ago, #metric restriction signs 🚗 were introduced on 🇬🇧 UK roads. From 13 August 1981, metric units 📏 could be used for the first time to indicate height, width and length restrictions on 🇬🇧 UK road signs. Weight restriction signs went metric on the same day. #metrication #roadsigns

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Metrication UK @metrication.uk · 26/07/2025

In 1969, Minister of Transport, Richard Marsh, announced plans to switch road 🚗 speed limit signs to kilometres per hour. hansard.parliament.uk/%E2%80%8CCom...

A diagram with 3 images, showing one method for the #metrication of speed limit signs.

The first image is of an imperial 50 mph sign - a red roundel showing the figure 50.

The second image is of a transitionary metric 80 km/h sign - a red roundel showing the figure 80, with a supplementary plate below the roundel showing a symbol km/h.

The third image is identical to the second, but with the supplementary km/h plate removed.

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Metrication UK @metrication.uk · 26/07/2025

#OTD 57 years ago, the Government confirmed that 1975 would be the end date for the UK's #metrication programme. Speed limits were to go #metric in 1973, but that date was postponed. 50 years after the 1975 target date, we are still waiting for the Government to complete its metrication programme.

The Government agree that programmes for the different sectors of the economy can be properly co-ordinated only if there is some general guidance on the timing. They therefore accept the end of 1975 as the target date for all provisional programmes, with the qualification that if this date proves to be unreasonable for any particular sector, the programme may aim at an earlier or later date.

Anthony Wedgwood Benn, Minister of Technology
26 July 1968

METRICATION
HC Deb 26 July 1968 vol 769 cc1167-711167

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Metrication UK @metrication.uk · 26/07/2025

For fun, here's an expanded version of the diagram, with a few more imperial units added, like cubic inches. How many people know all the imperial conversion factors? For anyone daunted by learning the metric system 📏, the equivalent #metric chart is included alongside.

A diagram comparing imperial and metric units of volume.

1 quart = 8 gills
1 firkin = 4.5 pecks
1 pint = 34.677 cubic inches

1 litre = 1000 millilitres

@metrication.uk

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Metrication UK @metrication.uk · 19/07/2025

The 440 yards (402.34 m) hurdles in 1966, was replaced by the 400 metres hurdles in 1970. The 220 yards (201.17 m) in 1966, was replaced by the 200 metres in 1970.

A page from an athletics programme for the 1970 Commonwealth Games in Edinburgh.

It shows the competitors for the semi-finals of the 400 metres hurdles, together with the previous games winners for the 440 yards hurdles that this event replaces.

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Metrication UK @metrication.uk · 19/07/2025

55 years ago this month, the Commonwealth Games went #metric. In July 1970, athletics and swimming events switched to the metric system. In track events 🏃, metres replaced yards. In field events, metres (to 2 decimal places) 📏 replaced feet and inches. In swimming 🏊, metres replaced yards.

Four athletics programmes for the 1970 Commonwealth Games in Edinburgh.

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Metrication UK @metrication.uk · 01/07/2025

The report noted: "the serious loss of time incurred by English school children in having to learn the complicated system of tables of existing weights and measures. ... no less than one year’s school time would be saved if the metrical system were taught in place of that now in use." 🏫 #metric

A diagram comparing imperial and metric units of mass.

The relations between 11 different imperial units of mass are shown, including:

1 pound = 291.67 pennyweights
1 ton = 2722.2 troy pounds
1 stone = 3584 drams

This is contrasted with the simple decimal relations of metric units of mass, such as:

1 kilogram = 1000 grams

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Metrication UK @metrication.uk · 17/06/2025

#OnThisDay #OTD 55 years ago, the first British decimal stamps 🏤📮 were issued. A 10p stamp might not seem "high value" today, but when stamps went #decimal in 1971, a 2nd class stamp ✉️ was 2½p. The 10p, 20p and 50p stamps served as 2/-, 4/- and 10/- stamps until D-Day - 15 February 1971.

A Post Office poster picturing the three new high value decimal stamps that were available from 17 June 1970. It reads:

"Decimal High Value Definitive Stamps

Three new high value decimal stamps 10p 20p and 50p will be on sale here from 17 June 1970"

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Metrication UK @metrication.uk · 24/05/2025

#OnThisDay #OTD 60 years ago, President of the Board of Trade, Douglas Jay announced the Government's intention for the UK to switch to the #metricsystem 📏 ⚖️ within 10 years. #metrication

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Metrication UK @metrication.uk · 20/05/2025

The posters highlight how metrology is driving innovation across multiple disciplines, topics covered by the posters include quantum technologies ⚛️ and advancements in health 🏥, industry 🏭, and energy ⚡.

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Metrication UK @metrication.uk · 20/05/2025

20 May 2025 is World Metrology Day. #OnThisDay #OTD 150 years ago, 17 nations signed the International Treaty of the Metre 📜📏, aka the Metre Convention. This marked the establishment of the BIPM, the 🌐International Bureau of Weights and Measures ⚖️📏. #BIPM150 #metrication #metric system

A poster promoting World Metrology Day
20 May 2025

150 years of the Metre Convention

"Measurements for all times, for all people"

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Metrication UK @metrication.uk · 05/05/2025

#OnThisDay in 1975, rail traffic went #metric. On 5 May 1975, #rail traffic switched to metric measurements for loads, capacities, tare weights and brake force.

A 1975 British rail #metrication information leaflet titled "Tons and Tonnes".

The leaflet includes the following text:

"On the traffic side of the railway we are chiefly concerned with distance and weight. As to distance, no metrication is planned for the time being. Unless the Government decides to change from miles to kilometres on the roads, we too will go on using miles, chains and yards - and of course speeds in miles per hour.

With weight measures the situation is different. Already the railway sales people have for some time been quoting rates for freight in metric weights, because so many of our customers are dealing in them, Now it is time for them to come into use on the operating side as well. From 5 May next, metric weights will become the standard for loads, capacities, tare weights and brake force".

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Metrication UK @metrication.uk · 13/04/2025

#OnThisDay in 1668, "An Essay Towards a Real Character, and a Philosophical Language", by John Wilkins, was published by the @royalsociety.org . It proposed a universal #decimal system of weights and measures, including a new Standard unit of length 📏, almost exactly equal to our modern day #metre.

"An Essay Towards a Real Character, and a Philosophical Language", by John Wilkins.

With highlighted extract:

"39 inches and a quarter ...
Let this Length therefore be called the Standard; let one Tenth of it be called a Foot; one Tenth of a Foot an Inch; one Tenth of an Inch a Line. And so upward, Ten Standards should be a Pearch; Ten Pearches, a Furlong; Ten Furlongs, a Mile; Ten Miles, a League, &c."

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Metrication UK @metrication.uk · 01/04/2025

The switch to the #metric system for timber was just one element of a comprehensive #metrication programme for the construction industry 🏗️🏠 which began in 1968 and was largely complete by 1972.

A #metrication information leaflet for the construction industry, published by the Ministry of Public Building and Works in 1968.

The leaflet details the metrication programme prepared by the British Standards Institution and agreed by all members of the construction industry.

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Metrication UK @metrication.uk · 01/04/2025

Do you still think of timber in terms of 2-by-4s? If so you are probably showing your age. #OnThisDay #OTD 55 years ago, timber 🪵 went #metric. From 1 April 1970, all sawn softwood 🪚🪵 was sold in cross sections in millimetres, and round metric lengths.

A 1970 #metrication information leaflet published by the Timber Research and Development Association.

The leaflet details the new metric standard range of sizes for sawn timber available from 1 April 1970.

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Metrication UK @metrication.uk · 05/03/2025

#OnThisDay #OTD 56 years ago, Minister of Transport Richard Marsh announced plans to switch road 🚗 speed limit signs to kilometres per hour. "We propose, subject to further consultation, that speed limits should become #metric in 1973." #metricsystem hansard.parliament.uk/%E2%80%8CCom...

A diagram with 3 images, showing one method for the #metrication of speed limit signs.

The first image is of a current imperial 50 mph sign - a red roundel showing the figure 50.

The second image is of a transitionary metric 80 km/h sign - a red roundel showing the figure 80, with a supplementary plate below the roundel showing a symbol km/h.

The third image is identical to the second, but with the supplementary km/h plate removed.

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Metrication UK @metrication.uk · 28/02/2025

Didn't going #metric mean that we would never need to know HOW BIG an #acre is? 🤷 Here's a handy diagram of antiquated units of area to decypher the acre used by today's estate agents 🏡 and TV shows 📺. Or, maybe they could just use square metres and #hectares. #KISS #keepitsimple #metricsystem

A diagram comparing imperial and metric units of area.

1 acre = 4 roods
1 rood = 40 perches
1 perch = 30.25 square yards

1 hectare = 10000 square metres

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Metrication UK @metrication.uk · 14/02/2025

Truly a man ahead of his time. In 1668, The Royal Society published another of his works, "An Essay Towards a Real Character and a Philosophical Language", in which he laid out the core principles of what would become the decimal #metric system, over 120 years later. metrication.uk/more/history...

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Metrication UK @metrication.uk · 10/02/2025

50 years ago this month, carpets 🚗🐕🐈 went #metric. In February 1975, #carpet retailers agreed to switch to metric unit pricing for carpets and floor coverings. But a failure to back up the voluntary move with legislation allowed the process to be reversed in 1977.

A 1970s #Metrication Board advertisement with a consumer guide to buying carpets and fabrics in metric units.

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Metrication UK @metrication.uk · 30/01/2025

Initially viewed as an interim standard, before the introduction of fully-modular metric bricks 🧱, the 1970 BS 3921 standard metric brick 🧱 has now been in use 👷🏠🏢 for more than 55 years.

Building Metrication News - 27 February 1970

30 January
Bricks and blocks: the new British Standard on bricks, BS 3921, is based on a format of 225 mm × 112.5 mm × 75 mm. This has not been reached without some controversy and further research on modular brick sizes is to be conducted. Findings on this could be arrived at in two to three years when it is anticipated that the present standard may be completely revised.

For blocks the standard format is for a length of 300 mm, a height of 225 mm and widths of 62.5, 75, 100 and 150 mm. Hollow blocks for floors have a length of 300 mm, a width of 300 mm and a depth varying from 75 mm to 250 mm in 25 mm increments.

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Metrication UK @metrication.uk · 30/01/2025

Bricks 🧱 officially went metric 55 years ago this month, when the new #metric British Standard on bricks was published. The new metric system size was already in use by the late 1960s, having been previously proposed by the Brick Development Association 🧱 in 1967.

The metric standard brick is based on a module size of 900 mm × 300 mm

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Metrication UK @metrication.uk · 20/01/2025

#OnThisDay #OTD 20 years ago, speed limits in Ireland 🇮🇪 went #metric. On 20 January 2005, all road speed limits 🚗 in the Republic of Ireland switched from mph to km/h.

Department of Transport, Ireland, information leaflet. Speed limits go metric from 20 January 2005.

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Metrication UK @metrication.uk · 01/01/2025

#OnThisDay #OTD 🥂 30 years ago, wine 🍷 serving sizes went #metric. From 1 January 1995, wine 🍾 served in glasses 🍷 was required to be sold in serving sizes of 125 ml or 175 ml, or multiples of either of these two amounts. Standard serving sizes enable customers to compare prices easily.

A large glass of white wine, filled to the 250 ml mark. The glass is graduated with 3 lines - at 125 ml, 175 ml and 250 ml.

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Metrication UK @metrication.uk · 01/01/2025

#OnThisDay 50 years ago, salt 🧂 went #metric. Salt in round metric pack sizes was first permitted #OTD on 1 January 1975. Imperial pack sizes ceased to be authorised on 30 June 1978.

A 1975 metric pack of Sifta table salt, labelled "METRIC PACK 750 g 1.65 lb"

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Metrication UK @metrication.uk · 25/12/2024

🎄 🎅 Season's Greetings 🎄 Did you know that Corn Flakes 🌽❄️ were one of the first food items to go #metric? - Switching to round metric pack sizes in 1976, and metric-only labelling in 1980.

Three metric Corn Flakes boxes: one from 1976 labelled "METRIC PACK 500 grammes 1.10 lb", one from 1980 labelled "500 g", and a "Season's Greetings" box from 2022.

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Metrication UK @metrication.uk · 21/12/2024

Switching ALL speed limits to km/h would be particularly beneficial at this time, given the current focus on reducing speed limits in built-up areas. For speed limits under 30 mph (48 km/h), the only practical current option is 20 mph. Whereas, with #metric, there are THREE possible choices.

Available speed limits lower than 30 mph - imperial vs metric

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