Talk:Metric and Imperial equivalents

See also: Talk:Metric and Imperial equivalents/archive

Boxes in the Temperature section

The Temperature section looks pretty crap with three boxes of different sizes and styles, all formatted differently, with only a tiny bit of regular text in the section. Essentially all three boxes aim to do the same thing: give the reader who only knows one system a rule of thumb for understanding the other system. Do we really need all three? Or is there some other way to fix the craptastic layout in this section? Texugo (talk) 18:18, 6 August 2014 (UTC)

I agree. The information is useful but the layout sucks. The poem could be turned into a quote at put the top of the section and then either of the comparison boxes could be discarded. ϒpsilon (talk) 18:41, 6 August 2014 (UTC)

The poem is exactly the sort of thing that we use infoboxes for. The tables are both useful; I don't see one replacing the purpose of the other. Powers ^(talk) 21:10, 7 August 2014 (UTC)

I don't mind keeping all three necessarily, but without more text in that section, I am at a loss as to how to make the layout look decent. Do you have any other idea, Powers? It does strike me that the tables could somehow be combined, but I'm probably not the guy for the job. Texugo (talk) 21:54, 7 August 2014 (UTC)

I suppose it would be best to present each one in order, with explanatory text separating them. Powers ^(talk) 00:45, 13 August 2014 (UTC)

Inofficial non-metric units

In some places ( I personally know for certain about Nicaragua) there are units of volume mass or distance that are not metric at all or "metricized" variants of customary units (a "Zentner" in German at exactly 50 kilogram comes to mind). How and where should we mention these, especially if their use is regional and they aren't really "standardized" in any way. e.g. a "vara" can be (in Nicaraguan parlance at least) a) a unit of distance (somewhere in the 10 (exp) 0 meter range) b) a unit of money (usually 1 Cordoba, but not necessarily) c) a unit of weight (I don't know how much).

I think it might be a good idea to give at least a hint that official use and policy don't necessarily determine the "reality on the ground" and maybe make a subsection "measurements" in country articles where appropriate. btw. this is less than trivial the NASA once lost a space probe due to a confusion between Newton (as the NASA uses) and pound-force (as Boeing, the company that wrote the program for the probe, uses) Hobbitschuster (talk) 16:34, 28 January 2015 (UTC)

These should definitely be mentioned if travellers are likely to encounter them. Whether they're mentioned at the national, regional or local level should be determined by the degree to which these measures are widespread. Ikan Kekek (talk) 06:58, 29 January 2015 (UTC)

Guide?

I wonder what needs to be added to upgrade this article to Guide status and make it a FTT candidate? The article is really short, but on the other hand, can anyone come to think of anything more to say about Metric and Imperial equivalents? Also, if we want to expand the article to cover other units (similar to ons, vara, jin etc. that are mentioned in the article) that are used elsewhere in the world, then the name of the article should maybe be just "Units". ϒpsilon (talk) 10:26, 24 August 2016 (UTC)

Maybe "Units of measurement" instead of "units". Hobbitschuster (talk) 16:46, 24 August 2016 (UTC)

Yes. :) ϒpsilon (talk) 18:12, 24 August 2016 (UTC)

I wouldn't expand to cover other units. Metric and U.S. standard / Imperial is all you need in any generic travel situation. The others are highly situational and best covered in the individual articles to which they apply. Powers ^(talk) 00:40, 25 August 2016 (UTC)

OK, so if we won't expand this one to other units, then is there something more to say about metric and imperial ones? ϒpsilon (talk) 13:44, 1 November 2016 (UTC)

I don't know that there's anything missing, per se, but what's here could use some better organization and some standardization of grammar and layout. Powers ^(talk) 15:15, 1 November 2016 (UTC)

Any other comments? Andre? ϒpsilon (talk) 17:25, 5 June 2017 (UTC)

Good looking out, Ypsi, as usual. It's not perfect, but I'd say it's a Guide. As Powers said, it's oddly laid out, but then again, by their very nature a lot of travel topic articles tend to be. -- AndreCarrotflower (talk) 17:30, 5 June 2017 (UTC)

Nautical Miles

This edit removed nautical miles. Do you agree that no mention is necessary? I think it might be useful to avoid confuses between miles and miles. Hobbitschuster (talk) 19:47, 14 March 2017 (UTC)

I agree with you. It's been restored. Powers ^(talk) 00:43, 16 March 2017 (UTC)

Wind speed approximations

I am not convinced it is important to give the exact figures for conversions between km/h, mph and knots. I know by myself, who often do quite advanced arithmetic in the head, cannot always be bothered to do the 3.6 exercise. Finding that dividing by four to get m/s is close enough made my life simpler. I am afraid showing the exact numbers make many people avoid the exercise. Sure, you can divide by four and then add 10 % to get about 1/3.6, but how many are going to do that even on a number like 56? On the other hand I'd be impressed if you estimated wind speed with an error of only 10 % (56/4=14, 56/3.6=15.6 m/s, both 7 Bf).

The mph is trickier, as 2:1.6 is off by 20 %, often landing on one Beaufort more or less, but still I'd think that is close enough, especially if one is aware of the error – and if we keep the table, the more exact values are there.

I think offering a simple model helps more than stating the true conversion factors, and the clutter of parenthesis – and the exact numbers themselves – makes fewer readers grip the model; in my experience people are too obsessed with exact numbers, especially when they cannot judge their importance.

--LPfi (talk) 19:35, 7 June 2017 (UTC)

Name change

I think Metric and Imperial equivalents is a bit of a misnomer, as although the U.S. customary and British Imperial systems are similar, they are not the same. In addition, we also cover some units that are not part of either system, such as the traditional Chinese system of measurements. I therefore propose that we re-name this article "Systems of measurement", and redirect "Metric and Imperial equivalents" to the new article name. What does everyone think? The dog2 (talk) 20:22, 30 August 2017 (UTC)

Possibly "Metric unit conversions" or "Metric unit equivalents). This removes the debate about Imperial units (used in the UK) and Customary Units (used in the US). Martinvl (talk) 20:58, 25 August 2022 (UTC)

Metrication by year graphic

The graphic was removed by a relatively new user claiming it to be inaccurate. Is it? Hobbitschuster (talk) 21:12, 26 November 2017 (UTC)

Well the image file for the graphic has several "This image requires updating because:..." templates plastered on it, and as a Brit I know that despite the graphic showing that the UK metricated in 1965, it is still only partially metricated. The problem may lay in the stated source for the data used, self-published data from the American metrication advocacy group, the US Metric Association. And although I haven't been active on Wikivoyage, I have made almost 15,000 edits on English Wikipedia and 18,000 edits on Commons over the last 12 years. DeFacto (talk) 22:47, 26 November 2017 (UTC)

I can't judge whether it's accurate or not, but I am wondering whether a map showing the current status instead of dates would be more useful to the traveler. Wikipedia uses such a map (File:Metrication.svg). There are a handful other maps on commons, but I think that one would be the most useful. What do you think? Drat70 (talk) 05:06, 25 January 2018 (UTC)

The date of metrication is irrelevant to the majority of travellers who don't have a TARDIS at their disposal. The file proposed by Drat70 is infinitely more useful, and will help to tackle common misconceptions. --ThunderingTyphoons! (talk) 12:34, 25 January 2018 (UTC)

Well a more recent date might indicate more lingering old style measurements, whether officially or in the heads of older folks. Hobbitschuster (talk) 19:48, 25 January 2018 (UTC)

True. I hadn't thought of that. But that information might be better conveyed in prose rather than as a map. Then again, it might not. Some people's brains are more visual than others'. ThunderingTyphoons! (talk) 19:53, 25 January 2018 (UTC)

New temperature chart

To be honest, I liked the previous temperature chart better—I thought it was visually clearer and easier to use for a general sense of what temperature corresponds to what and how Fahrenheit and Celsius match up. The new one is cluttered with a lot more numbers arranged in a less straightforward way, and it takes a lot more mental energy for me to try to understand it. What do others think? —Granger (talk · contribs) 13:46, 7 February 2018 (UTC)

I think I agree, at least somewhat. The beauty of the previous chart is that it looked visually like a thermometer, with the numbers simply increasing in both scales. The new version with text describing ranges is much harder to read and understand. It could be nice to flip the chart to be vertical, like a regular thermometer, but that does take up a lot of visual space on the page. --Bigpeteb (talk) 17:54, 7 February 2018 (UTC)

I've put back the previous chart. If someone finds a way to make it vertical while still keeping it easy to process and understand, that would be fine with me. —Granger (talk · contribs) 12:51, 10 February 2018 (UTC)

I changed the chart to begin with because the temperature descriptions didn't match international conventions and had problems working with the horizontal chart. I'll try again working with the horizontal chart format.Lcmortensen (talk) 02:30, 18 February 2018 (UTC)

What do you mean by "international conventions" in this context? Hobbitschuster (talk) 20:14, 18 February 2018 (UTC)

The conventions I followed is from the Köppen-Trewartha climate classification system. The problem was temperatures at the bottom end of the scale were too high to match their descriptions, so using the previous scale you would have the likes of Atlanta with "cold" winters and Edmonton with "frigid" winters.Lcmortensen (talk) 00:23, 20 February 2018 (UTC)

I don't think I'd call 23C hot, and isn't 0C freezing by definition? Obviously most of these temperature terms are inherently subjective, but overall the previous scale seems better to me. —Granger (talk · contribs) 00:35, 20 February 2018 (UTC)

I leave the words to native speakers, but I think it is odd that some of the versions had equal distance from 0°C to -40 and to +10 (which may in fact give the impression cold is cold, instead of realising that very cold and very very cold are different things). With vertical versions we do not have to shrink the scale. Having the table push down all text and fact boxes is also not that pretty. --LPfi (talk) 06:27, 20 February 2018 (UTC)

23C is definitely not hot! I'd call 30 hot and 27 is mildly hot. Ikan Kekek (talk) 07:05, 20 February 2018 (UTC)

I don't care for these numbers from Köppen-Trewartha. They may be useful and accurate for describing climate in terms of vegetation, but for travel most people are concerned with their bodies. --Bigpeteb (talk) 17:13, 20 February 2018 (UTC)

@Ikan Kekek: - the previous version had 24°C defined as "hot", so there has been no change there. All the changes have been at the lower end of the scale. Lcmortensen (talk) 03:38, 21 February 2018 (UTC)

OK, so the previous chart was designed by polar bears who can't stand merely mild temperatures. :-) Ikan Kekek (talk) 04:43, 21 February 2018 (UTC)

20-23 is room temperature, not "warm". Ikan Kekek (talk) 04:58, 21 February 2018 (UTC)

Depends on where you live - a house which can maintain at least 18°C inside is considered warm in New Zealand. Lcmortensen (talk) 13:53, 21 February 2018 (UTC)

When I was in primary school, 18°C was the recommended room temperature, but nowadays most people here (southern Finland) seem to agree with IK. I am a little confused by -10°C described as "very cold", but I am probably one of the polar bears. Suitably for the winter vacations we have wonderful winter weather with the sun shining and -18 in the morning and -8°C in the afternoon. I'd call that cold (not English winter, which we've seen a lot of lately, but cold enough for the snow to be dry) – I have even used my winter coat. If memory serves -15 was the limit in school for mandatory outdoor breaks and ice skating. Below -25 could be called very cold. I think parents are told not to have their babies take naps outdoors when it is below -20. --LPfi (talk) 16:22, 21 February 2018 (UTC)

Common prefixes

We seem to disagree about what the "most common" prefixes are (listed in the new section "Metric units"). Mega, giga and tera are common in the computer world (GB, Mb/s), but that is just one use, and one where everybody is using them (except for the 1024=2¹⁰ vs 1000=10³ thing). If somebody needs to be told about them, then it is in the context of memory cards, not in Metric and Imperial equivalents. --LPfi (talk) 08:45, 20 May 2018 (UTC)

It seems pointless to list those because, as the title says, they're common so everybody with enough intelligence to travel will already know milli, kilo, mega, and so on. Of course there is the confusion of 1024 bytes being referred to as kB whereas you'd expect them to be 1000 bytes, but that's not a relevant issue for travelers anyway because it's an ambiguity that only exists in computer storage capacity. ArticCynda (talk) 10:01, 20 May 2018 (UTC)

Has there ever been a measurement of computer storage not based on either 1000 or 1024? Hobbitschuster (talk) 08:52, 21 May 2018 (UTC)

512 B is common for disks :-) And bytes came in different sizes. But in practice I think the answer is no. And the difference between GB and GiB is not the most important issue with sizes, as the relevant thing is SD storage and similar, which have a lot of hidden storage (to not "shrink" when parts of it becomes too worn). But for metres, litres and grams the prefixes are important. If the prefixes are less known to US readers, they should probably be explained quite in the beginning. I am not sure the current format is ideal. --LPfi (talk) 21:19, 21 May 2018 (UTC)

Machine "words" came in different sizes; "bytes" were always two "nybbles" or eight "bits". K7L (talk) 03:28, 22 May 2018 (UTC)

The French translation for "bytes" is significant - they use the word "octet" which implicitly implies "eight". Martinvl (talk) 15:49, 1 March 2021 (UTC)

Yes. And octets are used in the internet RFCs too, exactly because bytes are not always 8 bits. w:Byte says "... that most commonly consists of eight bits" and that a byte usually was understood to be the size of a character. In communication I think what was transferred by 8+N+1 was a byte, and likewise with 7+parity or 6+parity. But that is quite irrelevant here.

The question was about the table of "common prefixes", which makes most of the section "Metric units" (really strange section name in this context). I cannot think of any traveller relevant context where T, G or M would be used (outside computing). Hecto is used in Sweden, perhaps nowhere else. Micro may have some use, but nano? Virus size and nanotechnology, but for travellers?

–LPfi (talk) 19:09, 1 March 2021 (UTC)

The prefix "M" is useful when expressing internet bandwidth - this might be important for some travellers. Martinvl (talk) 21:43, 2 March 2021 (UTC)

Yes, and G for flash memory size. But they will have used those at home too (or seen them in our internet and photography articles). They can of course be included for completeness. –LPfi (talk) 22:36, 2 March 2021 (UTC)

I don't even think we need to include them for completeness. The point of this article isn't to teach the metric system. It's to help people from the US, Liberia, Myanmar (as well as older folks from the UK and Canada) visit the rest of the countries in the world, and help the rest of the world visit those countries. We should be covering the kinds of measurements people use in their everyday lives; anybody needing measurements for, say, their work should be looking them up as needed and not trusting a travel guide! I have no idea why this article covers such obscure things as nautical miles, furlongs, surface area (the only use I can imagine for most travellers is the size of their lodgings), acre-feet, or horsepower (unless you're renting a sports car, but again, they can just look it up). --Bigpeteb (talk) 17:56, 3 March 2021 (UTC)

Furlongs should probably be handled in the horse racing article, but nautical miles are commonly used at sea, and if your destination is an island, it is good to know them. Area is useful to get a feel for the size of e.g. national parks. But yes, this is a kind of article that collects cruft. –LPfi (talk) 21:04, 3 March 2021 (UTC)

I've been to islands by plane and by ferry, and I've never needed to know nautical miles. I think that too is specific to Cruising on small craft or a similar boating article; not something travellers need to know unless they're navigating a boat or an airplane. --Bigpeteb (talk) 18:38, 4 March 2021 (UTC)

Symbol vs Abbreviation

The letters "km/h" are a symbol, not an abbreviation because they are the same regardless of language. For example, in Italian, "kilometers per hour" is "chilometri all'ora", but the shorthand form is "km/h" even though the letters "k" and "h" do not appear in the full Italian text, hence it is a symbol, not an abbreviation. Section 5.2 of the SI Brochure 9th edition clarifies this with the text "Unit symbols are mathematical entities and not abbreviations" (English) or "Les symboles d’unités sont des entités mathématiques et non des abréviations" (French). Martinvl (talk) 23:06, 16 February 2021 (UTC)

Should we use ml or mL?

Wikivoyage guidelines state that we shoull use the units of measurement that are most commonly used in the locality about which we are writing. The guideline goes on to state that the symbol "L" rather than "l" should be used for the litre, preceded by a prefix where appropriate. The official guidance appears to be:

• BIPM, in the SI Brochure states that either "L" or "l" can be used as a symbol for the litre. The SI Brochure contains the definitive description of SI.
• NIST, in their translation of the SI Brochure into (US) English state that "L" and "mL" are the preferred symbols for the litre and millilitre in the United States.
• British Government legislation permits either "L" or "l" to be used as a symbol for the litre but appears to favour the use of "L" for litres where there is no prefix and the use of "l" where there is a prefix.

I had a look at the markings on pharmaceutical, hygiene products, DIY product, gardening product, beverage (alcoholic and non-alcoholic), condiment, dairy product and fuel packaging. All used a lower-case "l" for millilitres, but an upper-case "L" for litres. (I live in the South of England). From my memory of having worked in Germany, Italy and the Netherlands and also having been on holiday in France, Italy, Australia and South Africa they do likewise. I therefore feel that Wikitravel should use "L" for litres, but "ml" for millilitres, except where local usage is otherwise. This is of course different to the English Wikipedia where the above arguments suggest that "L" should be used in all cases, but in my view, under their WP:ENGVAR rules, "mL" should be used where US English is used and "ml" should be used where British English is used. This matter is currently the subject of a RFC introduced by User:Beland. Martinvl (talk) 21:29, 27 February 2021 (UTC)

Firstly, this is Wikivoyage, not Wikitravel. I'll assume that was a slip of the tongue.

Secondly, I'm going to go out on a limb and say that since we're a travel guide, not an encyclopedia, it's not worth our limited time to standardize this. We're fine with lively colloquial writing rather than dry technically-precise prose, and I don't think our guides are substantially improved by consistent usage of "ml" or "mL". --Bigpeteb (talk) 21:58, 27 February 2021 (UTC)

UK

Apparently the UK is considering to go back to the imperial according to this. SHB2000 (talk | contribs | meta.wikimedia) 09:59, 18 September 2021 (UTC)

The Government had a consultation. The results were:

• Go back to the imperial system - 0.4%
• Allow more choice - 0.9%
• retain the status quo - 81.1%
• Complete the metrication process - 17.6%

Martinvl (talk) 22:00, 23 February 2024 (UTC)

Relevance to travel?

I'm wondering how relevant this point is to travel?

"Unlike almost all other units on this list, km/h is not the most commonly used unit for its purpose in science – there m/s dominates, keeping to SI base units. One meter per second is exactly 3.6 km/h. To give an intuitive approximation, world class sprinters do the 100 meter sprint in 10 seconds or less - which works out to 10 m/s."

It seems to me to be more suitable for Wikipedia. What do others think? Is there other text here that might not be useful to travellers? Ground Zero (talk) 22:11, 18 September 2021 (UTC)

Suits more to Wikibooks, but it could be useful for those travelling to do a marathon but that's what WB exists for. SHB2000 (talk | contribs | meta.wikimedia) 23:18, 18 September 2021 (UTC)

It seems to me this isn't relevant to travel. —Granger (talk · contribs) 09:17, 19 September 2021 (UTC)

A lot of people have the default assumption "metric is scientific". That is not entirely true (at least not with how metric is used in practice) for the cases of Kelvin for temperature and meters per second for speed. But figures that GZ would oppose what I do here on principle... Hobbitschuster (talk) 15:20, 19 September 2021 (UTC)

The principle being "relevance to travel". I understand the point you are making about assumptions regarding the scientific nature of the metric system. Is this relevant for travellers specifically? Ground Zero (talk) 16:00, 19 September 2021 (UTC)

What do other people with some experience from mph countries think? Does somebody have an opinion? –LPfi (talk) 17:59, 26 September 2021 (UTC)

In the US, for scientific things, they use the metric system, and that might explain why (from my personal experience). I can't speak for the UK, Belize or Liberia though. SHB2000 (talk | contribs | meta.wikimedia) 06:04, 27 September 2021 (UTC)

I have seldom seen m/s used in the UK. In cricket, the speed of the ball is usually given in mph, though occasionally if there is a direct feed from Australia for and England-AUstralia match, in km/h. Skiing events, which are often broadcast from the ALps (or other Continental European locations) will display a speed in km/h. Formula One motor racing also gives speeds in km/h (to three decimal places making mph conversions a pain). Martinvl (talk) 20:42, 25 August 2022 (UTC)

"The symbol for "kilometres per hour" is "km/h" regardless of how it is written in full in the local language"

I dispute that statement, because I remember seeing km/j on my trip to Malaysia during 2018 (think the j stands for jam?). These signs [1] [2] also seems to confirm that too. Should that sentence just be removed, or should Malaysia get a mention. (cc @The dog2, Ikan Kekek: as both of you know Malaysia better than I do). --SHB2000 (talk | contribs | meta.wikimedia) 06:30, 13 January 2022 (UTC)

Yes, they use km/j in Malaysia. The j does stand for "jam", which is the Malay word for "hour". The dog2 (talk) 06:36, 13 January 2022 (UTC)

So removing that statement? SHB2000 (talk | contribs | meta.wikimedia) 06:46, 13 January 2022 (UTC)

No. We could clarify it to "The symbol for "kilometres per hour" used by Wikivoyage is "km/h" regardless of how it is written in full in the local language". I don't think it would be helpful for readers to start using other symbols, although the local symbols can always be explained in text. Ground Zero (talk) 06:59, 13 January 2022 (UTC)

I think the sentence in the article is intended as travel advice for readers, not as a Wikivoyage style guideline. The style guidance would belong at Wikivoyage:Measurements. I support editing the sentence to clarify that it is evidently not true in all countries. Not sure we need to mention Malaysia specifically, but we could. —Granger (talk · contribs) 18:31, 13 January 2022 (UTC)

Yes, you're quite right. I misread this discussion. I support a clarification. Ground Zero (talk) 18:37, 13 January 2022 (UTC)

Percipitation

I did a quick check on units of measure by means of a Google search "Rainfall XXXX" where XXXX was the name of a British newspaper. All reports that I found after polling the Times, Telegraph, Guardian, Express and Mail gave rainfall in millimetres, though some reports included the inch equivalent. The Met Office warnings are always in millimetres.

I did a similar poll for snow. I only got one or two hits - entirely in centimetres. This is understandable - many Brits ski in the Alps (there is no real skiing in England and for people living in London and the SE, it is as almost as easy to get to the Alps as to Northern Scotland and the Alps have a much bigger selection of slopes. Apline snow reports are always in metric units.

Martinvl (talk) 20:22, 31 August 2022 (UTC)

Symbols, not abbreviations

Metric units do not have abbreviations, they have symbols. The subtle difference is that the "shorthand" used for any unit is independent of language, thus for the Italians "km/h" means "chilometri all'ora". On the other hand "VAT" is an abbreviation for "Value added tax" - in Italian this translates to "IVA" is an abbreviation for "Imposta sul valore aggiunto". Martinvl (talk) 20:41, 5 September 2022 (UTC)

Exact equality and approximate quality

Conventions used in article

A = B	A is exactly equal to B
A ≈ B	A is approximately equal to B

The lead section contains the sentence «Not all the conversions below are exact, even though the "=" is used». I propose deleting this sentence and adding the box that you see alongside this posting. This box would be added at the top of the first first sub-section ("Metric units"). Thus we could write:

• 1 ft = 30.48 cm

or

• 1 ft ≈ 30 cm

Either could be used, depending on whether we were trying to convey an exact equivalence to the user or a quick rule of thumb. Martinvl (talk) 22:38, 23 February 2024 (UTC)

The problem is that "≈" is not easy to type on most keyboards. We have the symbol in the symbols section of the special characters menu above the edit window, one can copy and paste, or one can use the HTML ≈ or the equivalent TeX code, but all these require some expertise, and the difference is seldom essential for travel needs. On the other hand, the page is quite well developed, so there is not necessarily any great need to add those characters (other than once, changing the equal signs to ≈ where appropriate). What do you think? –LPfi (talk) 08:43, 26 February 2024 (UTC)

How difficult is it on a normal Windows keyboard, though? On a Mac, it's as simple as using opt+X. --SHB2000 (talk | contribs | meta) 09:33, 26 February 2024 (UTC)

As User:LPfi says, it is likely to be a one-off exercise. If anybody needs to make an update after the main edit has been done the easy way for the novice editor will be to copy and paste the "approximate symbol" from elsewhere in the text. I was about to make the changes myself, but I thought it best to float the idea past other first, particularly the bit about the info box. Martinvl (talk) 17:20, 26 February 2024 (UTC)

I like the stringency aimed for with the proposal. I understand that stringency often is counterproductive in travel writing, but I am happy when I can achieve it without it disturbing the flow or enjoyability of the prose. I don't find the info box intrusive and I think its educative value makes it worthwhile in this specific type of article. The biggest danger in stating how a word (or whatever) is used in an article is that later editors don't follow that standard, which can get very confusing or misleading. In this case, I think the risk is small, but if it sets a precedent, the risk has to be acknowledged. –LPfi (talk) 09:29, 27 February 2024 (UTC)

Mostly we should give quick rules of thumb. Stating that something happens to be strictly equal is useful, so that those who need the figure don't have to look it up elsewhere. The exact figures can be given beside the approximation when the approximation is bad or the exact figure is easy, usually as a complement to the approximation (1 NM = 1852 m, 1 in = 2.54 mm). LPfi (talk) 09:39, 27 February 2024 (UTC)

Conventions used in article

A = B	A is exactly equal to B
A ≈ B	A is approximately equal to B
Approximations that are greater than 2% are noted in brackets

@LPfi: I agree with most of what you say, but I don't think we should go overboard with complementing the approximations. I suggest that we extend the box as shown. This we would write:

• 1 yard ≈ 1 metre (-10%)
• 1 inch ≈ 2.5 cm

I have chosen the value of 2% as this will allow the conversion factors of 2.54 and 454 to be quoted as approximate without further qualification.

Martinvl (talk) 15:23, 27 February 2024 (UTC)

I support using the symbol ≈ where appropriate, but I'm not so sure about the parenthetical percentages. I think something like "1 yard ≈ 1 metre (-10%)" is more likely to be confusing than helpful. If we want to provide exact figures in parentheses, I'd say we should provide them straightforwardly and precisely rather than as an approximate percentage adjustment. Still, I'm not sure how useful the exact values are for this article – if I'm on the road and need to convert units exactly (a rare occurrence) I just type "4 inches to cm" or whatever into Google rather than looking up the conversion and multiplying on a calculator. (In contrast the approximate conversions are useful to a traveller for intuition, memorization, and quick mental math, when exact precision is not needed.) —Granger (talk · contribs) 16:01, 27 February 2024 (UTC)

I don't think we should rely on travellers using Google, Siri or the like for doing conversions. What I meant is that I like that the °C/F formula is exact and that I don't need to ask Google, an encyclopaedia or the like to see that, when I want to check whether my rounding is too much off. Similarly with winds in knots and m/s and other cases where we happen to give the correct translations and not approximations. –LPfi (talk) 16:29, 27 February 2024 (UTC)

In fact, I like us giving the exact figures once (just once) and a rough measure of the "offness" where appropriate, such as the present

• 1 yard (1 yd) = 3 feet = 90 cm

[…]

• 3 miles = 5 km (off by 5%)

Much editorial sense is needed to avoid too much detail, too many examples etc., but I don't think we need very specific rules.

We don't need to tell that a furlong is 201.168 m; "1 furlong = 1/8 miles = 220 yards ≈ 200 m" suffices very well, as we already give the metric equivalent to a mile; we want to avoid figures with (many) decimals. And why do we tell that "Everest is about 8,848 m (29,031 ft) above sea level"? "Nearly 9,000 m (30,000 feet)" is much clearer.

–LPfi (talk) 16:50, 27 February 2024 (UTC)

I think that we are nearly singing from the same hymn-sheet. Under my proposal, we woudl have written:

• 1 yard (1 yd) = 3 feet ≈ 90 cm

[…]

• 3 miles ≈ 5 km (-4%)

Since the difference between 90 cm and 3 feet is less than 2%, I have not quoted the difference. However 3 miles is equal to 5*0.9654 km (ie 3.5% less than 5 km, whch is greater than 2%, so I have rounded the value. I have also put in the sign (minus) to show that 3 miles is less than 5 km and reduced the amount of text. Martinvl (talk) 17:55, 27 February 2024 (UTC)

I think the way to help travelers most is to give exact equivalents and approximate ones. Ikan Kekek (talk) 23:12, 27 February 2024 (UTC)

I think Ikan's approach works best. --SHB2000 (talk | contribs | meta) 07:16, 28 February 2024 (UTC)