Talk:United States customary units

ml or mL

I know it says "mL" on US soft-drink bottles, but isn't ml the more correct, internationally accepted term? The article mixes these two different ways of "spelling".

From BIPM:

This unit and the symbol l were adopted by the CIPM in 1879 (PV, 1879, 41). The alternative symbol, L, was adopted by the 16th CGPM (1979, Resolution 6) in order to avoid the risk of confusion between the letter l and the number 1. The present definition of the litre is given in Resolution 6 of the 12th CGPM (1964).

As I recall, they also recently reaffirmed that it isn't proper to use a script/italic l as a symbol.

Since both lower-case and capital are equally correct as far as BIPM is concerned, the difference is semantics. The US (and possibly Canada, don't know) tends to use the capital L, Europe seems to prefer the lower-case l or the disallowed script l. Guppy313 23:34, 29 October 2005 (UTC)

The symbol used to be a lower case L but the USA objected (rightly, in my opinion) that it was too easily confused with the digit 'one'. The use of the upper case L was legitimised by the BIPM and both symbols are now acceptable. Here in UK I see mostly lower case L when preceded by prefixes (e.g ml) and upper case when on its own (e.g. 2 L bottles of carbonated drinks). I wish we would just switch to the upper case L and use it consistently. Blaise 22:38, 28 March 2007 (UTC)

IMO this came from usuall style of handwriting in english-speaking countries. English-speaking people usually write "1" only as one vertical line, instead of full "1" and they write with lowercase letters instead of cursive writing. "12l" written like this iss indeed exactly same as "121". —Preceding unsigned comment added by 88.101.76.122 (talk) 13:09, 21 January 2008 (UTC)

Both l and L are correct, but that doesn't mean we cannot have a view on which is preferred for WP articles. I agree with Blaise that L is less ambiguous. Thunderbird2 (talk) 17:05, 21 January 2008 (UTC)

Actually, I thought that it was capital L because it was a derived unit. The only base SI units with capital letters are named after people, and every derived unit I can think of is a capital letter or a greek letter. In America, everyone uses capital L, even in mL. That is, everyone who doesn't Instant Message or text 24/7. Exp HP (talk) 01:20, 6 October 2008 (UTC)

The problem could be avoided entirely by using the equivalent cubic length unit of dm³ derived from the standard volume unit m³  :) - Parsa (talk) 16:59, 24 August 2010 (UTC)

I agree with the last poster - I thought the SI units are m, s, kg, A (plus something for light), litres being a derived unit. So should that section not just use m^3? —Preceding unsigned comment added by 128.232.133.79 (talk) 20:08, 10 May 2011 (UTC)

The US is the only industrialized nation ...

"The US is the only industrialized nation that does not mainly use the metric system in its commercial and standards activities"

• Well, on a de facto level, Canada also doesn't mainly use the metric system in its commercial and standards activities, its about 50/50.

99.238.33.85 (talk) 21:27, 19 May 2009 (UTC)

It would be a really hard issue to put a number on. For example, would you go by number of units sold or by cost? If shoppers seem to pay attention to the customary number on the label, but it would be illegal to market the item without an SI quantity on the label, does that count as customary or SI? Lots of tricky questions. --Jc3s5h (talk) 22:06, 19 May 2009 (UTC)

Well, when you say "3 inches" you are actually saying "3 x 25.4 mm" since "inch" is defined in terms of mm. The "inch" does not exist as an independent/organic unit of measurement, but merely as a multiple of the metre. I guess you could label products with a little bit of mathematics: what's to stop a label saying "LENGTH: 101.6 mm = 4 x 25.4 mm"? That is totally SI compliant, and the fact that 1 inch = 25.4 mm is something everyone using inches should know anyway (education system notwithstanding). 118.90.25.232 (talk) 10:58, 21 February 2010 (UTC)

I could think of something to stop a label saying "LENGTH: 101.6 mm = 4 x 25.4 mm". JIMp _talk·cont 01:21, 17 February 2011 (UTC)

Why is the US the only developed country to stand out against the international metric system? It always seemed odd to me that American's should hold so steadfastly to a pre-1824 British system of weights and measures. Talk about being backward... — Preceding unsigned comment added by 124.197.15.138 (talk) 20:14, 27 August 2011 (UTC)

Maybe for the same reason that some people still grow their own vegetables, shop organic, and prefer heirloom varieties to the corporate agribusiness foods that the big supermarket chains sell. Or for the same reason that the Chinese, Japanese, Koreans, Russians, Arabs, Hindus, and Israelis still aren't using the "modern" alphabet. Zyxwv99 (talk) 18:32, 26 November 2011 (UTC)

You're an ass.Jersey John (talk) 09:06, 29 November 2011 (UTC)

Hmm... I think this sentence is somewhat misleading. According to the source:

"At this time, only three countries - Burma, Liberia, and the US - have not adopted the International System of Units (SI, or metric system) as their official system of weights and measures. Although use of the metric system has been sanctioned by law in the US since 1866, it has been slow in displacing the American adaptation of the British Imperial System known as the US Customary System. The US is the only industrialized nation that does not mainly use the metric system in its commercial and standards activities, but there is increasing acceptance in science, medicine, government, and many sectors of industry."

Even in this discussion, at least one person has made the mistake of thinking the US is the only country not to adopt SI units. I think the first fact is more solid; "mainly" as a description is both ambiguous and subject to change. --Carbon Rodney 06:57, 28 August 2012 (UTC)

Often?

"... and U.S. medical practitioners often use degrees Fahrenheit for body temperature."

I think you'd be hard pressed to find a hospital, clinic, or doctors office in the US that doesn't use F. Saying often seems to underplay the near ubiquity of F in medical use. Maybe change often to generally or usually or almost always? 76.226.202.228 (talk) —Preceding undated comment added 06:38, 11 February 2010 (UTC).

My recollection in the last few years is some US medical treatment locations use Celsius, some use Fahrenheit. I think a source is needed that conducted some kind of survey in order to know the best word to use. Jc3s5h (talk) 16:00, 11 February 2010 (UTC)

Questionable Opening paragraph

"The U.S. is the only industrialized nation that does not mainly use the metric system in its commercial and standards activities"

Thats a very loose statement, as it also applies to the UK‎ because usage of Imperial unit is widespread; body height (measured in feet, inches).. body weight (measured in pounds, stone).. road sign distance (measured in yards, miles).. car speed (mph)... beer/milk (measured in pints).. petrol (gallon).. etc etc. Its a misnomer that the UK‎ has "officially adopted the metric system" because Imperial is used throughout (for example its illegal to have road signs in metric). The only thing the UK has agreed to (to appease Europe) is to allow metric appear ALONGSIDE imperial measurements in SOME cases... but everyone uses imperial anyway. StiffyAdams 19:52 Feb 15, 2010 (UTC)

The part about the UK using customary units for petrol and road signs seems to be true, from what I've read, but that's only one small part of "commercial and standards activities". In the market, milk is only a small part of what is offered for sale. In a pub, the beer is sold by the pint; I imagine few of the other items for sale in a pub are measured out to the customer (I'm pretty sure I'd never hear a server in a pub say "here's your 400 g of bangers and mash"). The pub itself most likely buys all its supplies in metric units. And personal measurements are not commercial when used in casual conversation; they would only be commercial if health professionals use feet, inches, stones, and pounds, because the health professionals are getting paid. So are feet, inches, stones, and pounds, used in professional health care settings?

I think the weakest part of the phrase is "standards activities" because a great deal (maybe a majority) of US standards activity is conducted in metric. Jc3s5h (talk) 22:32, 15 February 2010 (UTC)

When I lived in the UK, from 2002-2006, a law had been passed that all goods and items sold would have the metric measure labelled as the PRIMARY unit. However, they still listed the old imperial units in smaller print. You would find such oddities as 2.1 Litres of milk (instead of just 2) as they original bottle size was in pints or whatever. It is therefore not a misnomer, but an official UK law to use the metric system first and foremost. However, there is a lengthy conversion process to go through for cars, street signs etc. Fortunately in Australia we've been using the metric system much longer, and it's only the old people who still use a few antiquated measures, mainly for body heights and weights. —Preceding unsigned comment added by 202.89.162.154 (talk • contribs) 13:05, 6 November 2010

The only things I'm aware of that officially use imperial in the UK are road signs (miles and mph) and beer (in pints). Everything else officially uses metric (though the milk is sold in 578ml bottles which happens to be the same a pint), and though beer is in pints, wine and spirits are sold in ml. Petrol certainly hasn't been sold in gallons for 20 years or more, and though many people describe themselves as 6" the docotor would record 1.8m (such as to calculate BMI, which is metrically defined). —Preceding unsigned comment added by 128.232.133.79 (talk) 20:21, 10 May 2011 (UTC)

Mass

Is the pound considered to be a unit of force or mass in the U.S. ? Here in the UK the lb is obsolete, but it was legally defined as a unit of mass, equivalent to a stated fraction of a kg in the Weights & Measures Act (1963), and there is never any ambiguity about it. But judging from what I have seen on the internet this is a matter of controversy and confusion in the USA. Do you have anything equivalent to an Act of Parliament over there which gives an authoritative answer to this question ? A related point is that historically in England, up until 1963, the pound Avoirdupois was considered to be a force or weight. So the historical aspects of the main article are incorrect in discussing the historic English unit under the heading of mass. Anyone who is interested in the history of this unit would be sensitive to this matter, so I think it should be corrected. In anticipation of any dispute over this, I will refer to the Weights and Measures Acts of 1878 and 1958 and 1963, and also, as a matter of technical interest, to 'Useful Rules and Tables' by W J M Rankine, (Professor of Engineering at Glasgow University, and originator of the Rankine Cycle) London, 1889. Rankine defines weight as a gravitational force (p 305), and the lb as the weight of a certain piece of platinum under stated conditions of temperature, atmospheric pressure, and location (all pertinent to the weight of a certain mass) on p 97. On p 245, Rankine defines absolute units of force (as distinct from units of weight) thus - ‘Absolute units of force in the weight of an unit of mass: in British units 32.2 nearly…’ (p 245). This can be interpreted as meaning that the absolute unit of force in the British system is 1/32 lb-wt. Furthermore, in giving a rule for calculating centrifugal force (p 246), Rankine states - 'Multiply the weight of the mass by the square of its linear velocity and divide by the radius. The result will be in absolute units which may be converted into units of weight by dividing by g'. This rule only makes sense if 'the weight of the mass' is measured in pounds. Thus if we take a certain mass having a weight (gravitational force) of 1 lb-wt, rotating with a speed of 1ft/sec at one foot radius, the centrifugal force will be 1 absolute unit or 1/32 lb-wt, which is correct. The 'absolute force unit' of ~1/32 lb-wt was called the poundal in the foot-pound-second system, and was defined as the force required to accelerate a mass of 1lb at 1ft/sec^2. In the UK the pound changed from being a force unit to being one of mass in 1963; compare the Weights and Measures Acts of 1958 and 1963; the former defines the pound by reference to the W & M Act of 1878 in which the pound is a weight, while the latter explicitly states that the pound is a mass. Dr A. J. Smith CEng Sept 2010 —Preceding unsigned comment added by 82.32.49.157 (talk) 13:39, 20 September 2010 (UTC)

For purposes of trade and commerce, the pound is a mass in the US; see Refinement of values for the yard and the pound. However, it is used as a unit of force as well, and which is intended must be determined by context. Jc3s5h (talk) 14:45, 20 September 2010 (UTC)

MONDAY, December 17th, 1792.

Agreeably to the order of the day, the Senate resumed the consideration of the report of the committee made April the 5th, 1792, on the subject of weights and measures, together with the motion made thereon the 6th instant—Whereupon,

A motion was made to postpone the consideration thereof, and to

Resolve, That the present measures of length be retained and fixed by an invariable standard; that the measures of surface remain as they are, and be invariable also as the measures of length to which they are to refer; that the unit of capacity now so equivocal, be settled at a medium and convenient term, and defined by the same invariable measures of length, that the more known terms in the two kinds of weights be retained, and reduced to one series, and that they be referred to a definite mass of some substance, the specific gravity of which never changes; and that a committee be appointed to bring in a bill accordingly—and after debate,

Ordered, That the consideration of this motion be deferred until tomorrow.

6th. That the unit of weights shall be a pound, which shall be equal to the pound Avoirdupois, now in use, and shall be equal in weight to a quantity of rain water, twenty cents of a foot square, and forty cents deep, or sixteen thousand cubic cents of a foot, measured and weighed in a cellar of uniform natural temperature.

-- Journal of the Senate of the United States of America: being the second session of the Second Congress, begun and held at the city of Philadelphia, November 5th, 1792, and in the seventeenth year of the sovereignty of the said United States.

Printed by John Fenno, 1792 - 100 pages

Zyxwv99 (talk) 02:30, 18 November 2011 (UTC)

Calories

Why are calories listed here? These are metric. JIMp _talk·cont 22:08, 16 February 2011 (UTC)

According to this federal register notice the official interpretation of SI for the U.S. may be found in NIST special publications 330 and 811. In S.P. 811, section 5 table 11 indicates the calorie is outside the SI and not acceptable for use with it. Since SI is the only form of the metric system officially recognized in the US, then what can we call the calorie? It is traditionally used in the U.S. and falls in the same category as the foot, inch, BTU, etc., in that the government is aware of it but the Congress has never enacted, there is no current federal legislation recognizing any measurement system other than SI. Jc3s5h (talk) 22:25, 16 February 2011 (UTC)

The calorie is the amount of energy required to heat one (kilo)gram of water up by one degree Celcius. It's metric. There's nothing US customary about it. If the US government doesn't recognise non-SI metric units as actually metric, that doesn't make them customary ... it just makes the US government mistaken. They could write a law defining a carrot as a fruit, that wouldn't mean that it is a fruit. JIMp _talk·cont 01:18, 17 February 2011 (UTC)

• You're right, but the 2 calories lines are in the "Other units" section. -Fnlayson (talk) 02:47, 17 February 2011 (UTC)

There is not now, and never has been, any systematic federal definition of American customary units. American customary units are whatever units Americans customarily use. The calorie has been around about as long as other heat and energy units, and indeed, a large fraction of the period of independence of the U.S. So who is to say it can't be metric and customary at the same time? No one can say that officially the calorie isn't a customary unit because there is no official definition of a customary unit. Since NIST is the main force behind any measurement laws, and NIST is anti-customary, it is unlikely that Congress will ever pass an official definition of customary units. NIST just wants to ignore them and hope they eventually go away. Jc3s5h (talk) 03:01, 17 February 2011 (UTC)

Troy weights

This is not correct:

"To alleviate confusion, it is typical when publishing non-avoirdupois weights to mention the name of the system along with the unit. Precious metals, for example, are often weighed in "troy ounces", because just "ounce" would be more likely to be assumed to mean an ounce avoirdupois."

Look at the troy ounce article. There's a picture of a gold bar that has the word "ONE OUNCE FINE GOLD" stamped on it. Go to Google Images and try finding a picture of a bar of gold that has the word "troy" on it. Lots of bars denominated in ounces, but they don't say troy. In the precious metals trade, when you say "ounce" people just assume you mean troy. In academic, encyclopedic writing, you would of course be more specific, but I mean "in the trade" which is essentially common usage.Zyxwv99 (talk) 01:57, 18 November 2011 (UTC)

The case of ounce being stamped into gold bullion (or any other precious metal) is an excellent example of the context clearly meaning the weight is not avoirdupois. But having "ounce" written generally, or associated with most household or industrial goods would almost certainly imply avoirdupois. —EncMstr (talk) 03:59, 18 November 2011 (UTC)