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Only the USA, Liberia and Myanmar still use imperial weights and measures

February 25, 2021 — BarryK

Here in Australia, we get those TV shows from the USA, house restoration, building off the grid, etc., and I find it amusing when they talk in imperial units.

For example, they will measure a length of timber as 5 foot, 3 and 3/8 inches. The thing is, math calculation is messy when doing it in fractions. It is also messy to have non-metric conversions, for example 12 inches equals 1 foot.

Then there is ounces, which could mean a weight or a volume. Messy again.

And of course there is degrees Celsius -- so much neater to have zero degrees the freezing point of water, and 100 degrees the boiling point.

Australia converted to the metric system of measurements in the 60s, and today I wondered what countries in the world are still using imperial measurements -- got reminded of this today when publishing weights in grams in the previous blog post.

According to this link, only the USA, Liberia and Myanmar:

However, most countries that were previously part of the British Empire are still using imperial measurements here and there. There are some measurements where it was just more convenient to stay with imperial. TV screen size for example.

The UK, where the imperial measurements originated, is still using miles-per-gallon, and gallons when filling up the petrol tank.

There were apparently moves in the USA to become metric, and I wonder why it didn't happen. I was in high school here when it happened, and I recall the government mandating that things like measuring tapes had to become metric -- in other words, the Federal Government forced it to happen. In the USA, the homeland of the "rugged individual" and "free will", perhaps the government did not have sufficient authority (or cohesiveness, or motivation) to force it? or were the State governments insufficiently aligned to force it to happen? Just speculating.

EDIT 2021-02-26:
David, in the UK, commented:

We buy petrol in litres but range is mpg. We buy beer in the pub in pints but litres in cans.

John G., in the UK, clarified that petrol has been sold in litres since the 1980s:

In the UK petrol has been sold in litres, rather than gallons, ever since the 1980s! See

For fuel consumption, the UK still uses miles per gallon rather than miles per litre or even kilometres per litre. Bizarrely the EU uses an inverse measure, litres per 100 kilometres.

Yes, we also use litres per 100km here in Australia. The link sent by John G. is very interesting, it has information about Australia:

...which shows conversion milestones in 1971 and 1974. My memory, though, is of conversions happening while I was still in high school, in the late 60s.

Now I'm curious, is my memory faulty? Found this:

...ah, it started in 1966, with change from pounds, shillings and pence, to dollars and cents.

The Wikipedia also explains the situation in the USA, Canada and the UK:  

EDIT 2021-02-28:
David W. in the USA commented that the US has embraced metrication somewhat:

I'm in the States, and do recall an attempt in the mid-1970s to sell
gasoline by the liter, but it failed -- I believe because of massive
pushback by the public.

Since then it's been a series of baby steps. Goods are often labeled
with both imperial and metric measurements, in that order.

Speedometers have been labeled with miles *and* kilometers for decades.

The only metric measurement I can recall Americans having more or less
fully embraced is vehicle engine size. You basically don't hear it
referred to in cubic inches anymore, just liters. And of course,
Americans have fully embraced motorcycle engine sizes in cubic
centimeters for at least 50 years.

Yes, engine sizes in litres ("liters" in the US) is something that I noticed on those TV shows from the US where they restore old cars, or greatly enhance a car. Just looking at Channel 96 here in Perth: "Garage Squad", "Overhaulin", "Diesel Brothers" -- shows from the US. There is one from the UK, "Wheeler Dealers" -- where I picked up the info about the UK is still using miles and mpg.

Michael A. in Australia commented that the car manufacturers probably pushed back metrication attempts in the US:

You have to take into consideration that back in the 60s/70s the BIg 3 car manufacturers here were GM, Ford and Chrysler (Leyland was a drop in the bucket, plus a couple of others like Lightburn - niche car really)  - I'm sure they would have pushed back _hard_ against metric, extra cost involved in converting speedometers, fuel gauges etc.

So I believe that metric wasn't mandated for cars until 1974, and that is about the time we saw 'speed limit 35' signs disappear replaced by 60 within the red circle. I was 9 years old then! 

I had assumed that NASA, a scientific organization, would be using metric units, but did a check today and found that is not so, they use a mix of imperial and metric:

On 29 March 2010, NASA decided to avoid making its proposed Constellation rocket system metric-compliant, especially due to pressure from manufacturers; ultimately the program was discontinued. It had been predicted that it would cost US$368 million to convert to metric measurements for parts made by both NASA and external companies. Constellation would have borrowed technology from the 1970s-era Space Shuttle program, which used non-metric measurements in software and hardware.[16] NASA's non-compulsory position has contributed to at least one major mission-failure: in 1999, a contractor's use of pre-metric units caused the disintegration of NASA's $328 million Mars Climate Orbiter.[17] Despite NASA's non-compulsory policy, commercial space manufacturer SpaceX currently designs its systems (e.g. Dragon and Falcon 9) using metric units.

...that has really surprised me. Good that SpaceX is using metric units.  

EDIT 2021-03-01:
Feodor commented about the US auto industry:

GM in Detroit experimented with the metric system in the 1970th. Yes, it failed
when imperial screws, washers and nuts got mixed up with metric counter parts.
Same problem existed with the 1/2" tools for the metric system. A friend of my
parents named Karl Bohmer who lived in Windsor/Ontario worked all his life for
GM in Detroit. His job was to fix every thing that showed up broken at the end
of the assembly line. He was very happy when that metric mixing match ended. 

EDIT 2021-03-2:
Amitav commented from India:

Very interesting discussion on Metric and Imperial units! In India, everything is in metric, as we are a relatively young country. With one exception: The Aviation industry seems to still work in Imperial! I started as an engineer in the automotive industry, and my company started its first aerospace products in 2014. One big - and annoying - barrier was suddenly everything, including even nut and bolt sizes, had to be in Inches, and weird fractions :) . I would be interested to know if the Australian Aviation Industry use Metric measures?

I imagine that it would be mixed, as Australia acquires a lot of aviation (and military) hardware from the USA. Did a quick search, Found this at a technical college:

Exposure and use is given to imperial and metric units as used in the aviation industry.

After successfully completing this unit, you should be able to:
1. to describe how factors such as weight, wing area, engine power, drag and high lift devices effect aircraft performance and to apply basic estimation techniques to determine an aircraft configuration to meet a specified mission,
2. to compose gust and manoeuvre diagrams,
3. to describe the principles behind jet transport performance in an airline environment and how they affect the cost of operation,
4. to be able to use imperial units in basic engineering calculations.

It looks like the same problem as in India. Young people coming into the college course would have mostly used metric units at school. 

Have received more feedback, but calling a stop to this blog post!     

Tags: ethos