Category talk:Conversion templates

Naming convention

I suggest using CamelCase names for the sake of readability as most of these are intended to be used within #expr (see m:ParserFunctions). The main reason I suggest CamelCase is that it keeps function names from breaking across lines (no spaces; yes you can use underscores but that gets ugly fast). If/when this grows large enough, it would probably be wise to protect these fully and create a single reference doc for this API (probably as part of a new WikiProject; maybe Wikipedia:WikiProject Template Functions?). See also Template:IsLeapYear (edit | talk | history | links | watch | logs) (which also uses CamelCase). —Locke Cole • t • c 01:52, 15 April 2006 (UTC)

one way conversion

I think it's unnecissary to have conversion-templates two-way, I think that it only need to be conversion to SI-units, not from. For example you might need to convert from mile, but whan do you need to convert to? _→AzaToth 15:40, 15 April 2006 (UTC)

Suppose a user in England is writing the article. Their references are going to list things in kilometers, but they might think to provide the value in miles for readers who still use imperial units. --CBDunkerson 20:35, 15 April 2006 (UTC)

<joke mode on> Oops, I'm going to write a policy right now.... P: Avoid using miles (What about WP:AUM? Oh noes! already taken). Sorry for me being childish... --Ligulem 21:12, 15 April 2006 (UTC)

=) —Locke Cole • t • c 21:55, 15 April 2006 (UTC)

Yup, that's why I thought they might be needed. =) —Locke Cole • t • c 21:55, 15 April 2006 (UTC)

I belive that imperial units should only be used if the source data was using those, and no exact SI-eqvivalent is found. _→AzaToth 22:21, 15 April 2006 (UTC)

Speaking as someone living in a country using Imperial units everywhere, I respectfully disagree. Using conversion templates we can have both formats in an article with no excuse for excluding one or the other (if you only have the imperial unit value available, use a conversion template to convert to the metric system; and vice versa). Then readers from nations which don't utilize one system or the other can still read/understand the article without whipping out a calculator (this also saves editors from performing conversions improperly). —Locke Cole • t • c 06:04, 20 April 2006 (UTC)

I agree, but do think that SI units should generally be listed first with the imperial in parentheses -> e.g. '10 m (32.81 ft)'. The SI are more 'internationally common' and used to some degree even in countries which haven't fully converted. --CBDunkerson 10:24, 20 April 2006 (UTC)

I'd rather avoid measurement system holy wars, but if you feel like tackling it, be my guest. =) FWIW, I agree with you that SI first and Imperial in parens makes sense, but I suspect a debate on which goes first may get ugly (ala Wikipedia:Eras). —Locke Cole • t • c 10:38, 20 April 2006 (UTC)

It certainly might. There are a lot of us who insist that as a general rule, the original measurement should go first, followed by any conversions. That means, of course, that even within one article, some measurements might be English units first, some Fred Flintstone non-SI metric units such as calories or Pferdestärke (PS) first, and some SI units first (and a few articles even have original measurements in other units neither English nor metric, such as the shaku). Of course, there are many cases when either could be considered original, and there are various levels of being original (what was used as a source by a particular editor adding the information, vs. the units in which the original measurement was made, etc.) but those are different issues. Gene Nygaard 14:38, 22 April 2006 (UTC)

The original measurement should go first, and a conversion should be included in parentheses if needed. (There is no need in a scientific article to convert to imperial units, but in an article about road lengths or car engines it might be appropriate.)

I also like the fact that CBDunkerson's example has linked units. Can this be added to the templates?

• {{km to mi|100}}

creates

• {{km to mi|100}}

but should create

• 100 kilometers (62.1 mi)

— Omegatron 13:59, 5 April 2007 (UTC)

Significant Digits

Is there a policy regarding the use of significant digits within these templates? I was reading the article, California_Southern_Railroad#Cajon_Pass, and saw the following nonsensical text:

...until reaching the summit 6 mi (9.656 km) further...

Now, I know that 1.000 miles equals 1.609 kilometers, and therefore 6.000 miles equals 9.656 kilometers, but "6 miles" is absolutely not the same as "6.000 miles" and therefore does not equal 9.656 kilometers. Implicit in the expression "6 miles" is the notion of "± 0.5 miles", therefore the number of kilometers represented by "6 miles" could be in the range of:

• 5.5 miles = 8.9 kilometers
• 6.0 miles = 9.7 kilometers
• 6.5 miles = 10.5 kilometers

...so the number of kilometers is something like 9.7 ± 0.8 kilometers. Given the wide implied error in the miles measurement, going down to the precision of a single meter in the kilometer measurement is just silly.

It seems to me that the most correct conversion would be 10 kilometers, although the given the low value of units involved and the difference in the implied error based on the different scale of the units, this would run the risk of overstating the distance because "10 kilometers" implies "between 9.5 and 10.5 kilometers" which only represents the high end of the range shown in the list above.

I must have too much time on my hands, but this bugs me. Can anyone suggest a solution? Mmccalpin 16:18, 12 July 2006 (UTC)

I'd suggest trying to get a more precise initial measurement, saying 'approximately 6 miles (9.656 km)', or leaving it as just '6 miles' with no conversion. As you note, trying to maintain significant digits in the converted value requires an assumption about how the original was rounded. I like the 'approximately' method because it makes clear that an exact measurement is not intended and then translates '6 miles' for those more familiar with SI units. --CBD 01:15, 13 July 2006 (UTC)

It should say:

...until reaching the summit 6 mi (10 km) further...

— Omegatron 14:04, 5 April 2007 (UTC)

Use "{{mi to km | 6 | precision = -1 | abbr = yes}}" to get "{{mi to km|6|precision = -1|abbr = yes}}." Sdsds 15:22, 5 April 2007 (UTC)

Universal vs. specialized conversion templates

The following has been copied from User talk:CBDunkerson

Hi, CBD! Recently, for no apparent reason at all, I thought that having some conversion templates would have been nice. Unfortunately, it did not occur to me to do a prior research, so I failed to notice that a collection of such templates is already available at Category:Conversion templates. Before I found that category, I produced the following templates: {{km to mi}}, {{mi to km}}, {{m to ft}}, {{ft to m}}, {{km2 to mi2}}, {{mi2 to km2}}, {{m2 to ft2}}, {{ft2 to m2}}, {{C to F}}, and {{F to C}}. Now, these are much nicer and more convenient than some of the templates that have been created so far ({{FootToMetre}}, for example), so at least part of my work has not been in vain. However, their functionality is not much of an improvement over {{conv-dist}} and the likes which you created. Hence, I don't see a point for me to continue with this. I only have one request for you: could you incorporate some of the functionality of my templates into your topical templates? Mine allow the users to specify whether they want the output to show full or abbreviated unit names, whether the unit names should be spelled in American or Commonwealth English if full unit names are output, whether the unit names should be wikified, and allow to specify the precision of the result. If you could do that, we can deprecate my templates and then clean the whole Category:Conversion templates up. Cheers,—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 17:49, 7 March 2007 (UTC)

Hi Ezhiki. Yeah, there are several different variants on conversion templates. The options you describe all sound doable, but one difference between the templates you've created and 'conv-dist' not noted above is that 'conv-dist' only works properly when substituted while yours are designed to not be substituted (if they were they'd copy in all the conditional logic). Converting 'conv-dist' to a 'not substituted' format is easily accomplished, but I haven't been able to get it to work as both - only one or the other. I've been sticking with the substituted version because it leaves an end result which is just the actual text of the measurement(s) in whatever format specified. On the other hand, unsubstituted templates are easier to use and spread faster because people see their syntax on pages and re-use them. Any thoughts or preferences on this? --CBD 03:14, 9 March 2007 (UTC)

Having had several discussions on the topic with various people since the time I posted my original message to CBD, I now think that having both universal and specialized templates makes sense. The people I talked to all had different opinions—some really liked the functionality {{Convert}} provides, others liked it but found it unfit for certain purposes (such as using it from inside another template), others liked the {{km to mi}} type of templates. All in all, I think if we have one universal template ({{Convert}}), several general templates (such as {{Conv-dist}}), and a set of little single-purpose templates (such as {{m to ft}}), it should cater to everyone's needs. My only remaining concern is about substitution: obviously, huge resource-intense templates such as {{Convert}} should be substituted, but what about the single-purpose ones? On one hand, something like {{mi to km}} does not really eat up a lot of resources, but if it starts being regularly used, what happens then? As of now, the single-purpose templates cannot to be substituted (to my shame, I did not test them correctly; thanks to CBD for enlightening me—it was not as much by design as it was a design flaw). Anyway, the bottom line is that I'll happily create more single-purpose templates if there are no serious objections to that.—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 16:25, 9 March 2007 (UTC)

Thinking on the idea of having both 'convert' and 'm to ft' style templates (and keeping them consistent) I came up with a new design. See {{conv}}, {{m-ft}}, and {{format measurement}}. The 'conv' template there just calls 'm-ft' and similar templates and thus would be entirely optional... people could use either {{conv|7|m|ft}} or {{m-ft|7}} and get exactly the same results / have all the same options. The 'format measurement' template does all the work of formatting the output, but receives its instructions for doing so from 'm-ft' rather than huge switches for every possible combination. It thus has a much smaller 'transclusion footprint' than {{convert}}. Under this format there'd be one template per conversion type ('m-ft', 'm-km', 'g-lb', 'mph-kph', et cetera), all of which would call and be formatted by 'format measurement' and could optionally be called by 'conv'. Only the 'm-ft' template has been created currently, but the others could be easily cloned and updated from that. In addition to that structure I'd then suggest a single large template along the lines of {{conv-dist}} to handle cases where conversions should be substituted - the template size wouldn't matter as after substitution only the resultant text would remain. Thoughts? --CBD 19:20, 10 March 2007 (UTC)

I was looking for you CBD, and this was the last thing you did earlier today. Turns out I was giving kudos on Ezhiki on these a few days ago. I'm darn certain if they're stabilized we can find some interested customers on Wikiversity and Wikibooks for them, along side the many here. I'm not sure it's necessary to subst even big-boys like convert so long as the article isn't all that complicated, and I would suspect these sorts of things aren't on large articles. Is there anyway to detect when a page is starting to reach large pre and post expansion template limits without looking at the HTML? Or do things just break after a certain point as I'm given to understand from the discourse late last summer that generated the template doc page pattern?
  I put a feature request in as a follow-on to some email conversations we had for a self-subst: Magic word. That is it only executes when encountered within template flow, but will clean up the source calling text, and just patch in the results of the current expansion much like Special:ExpandTemplates. I also asked for them to implement it so that it doesn't include unnecessary residue logic... I'm thinking in terms of {{indent}} (switch based) and {{catlst}} (if-then-else chain) when say Indent was asked for five spaces and similarly in catlst, only five or six of the If statements would evaluate as true...
  The two comments I've to make is the {{m to ft}} and {{ft to m}} are probably going to be the most used by the lay editor, in matters geophysical, and should have as small include footprint as possible. And like many of the utility or tools templates, these all need somekind of publicity... a handbook page, so as that's a goal of WP:TSP, suggest you sign up! <G> Cheers! // FrankB 03:30, 11 March 2007 (UTC)

Hey Frank. The smallest 'footprint' can be achieved by having each template fully self-encapsulated... but that becomes difficult to keep consistent. People will add a new feature to one template, but then people try to use it on others and it doesn't work or (worse) it is implemented differently there. The greatest consistency is created by having one template, but then you run into transclusion problems if it gets used alot on one page. I believe the best compromise is the aforementioned method of having one template for formatting and then individual templates for each conversion type. Only a little bigger than fully autonomous templates and nearly as easy to keep consistent as a single template. Some better means of handling parserfunctions and the like in substitution would be a major boon. As to transclusion limits, so far as I know looking the current transclusion size up in the page source or seeing the broken templates when the limit is exceeded are the only ways to know. --CBD 19:34, 11 March 2007 (UTC)

The {{m-ft}} idea is absolutely great! I just want to mention that one of the requests I received was to add a new formatting option to the templates—one that's compliant with this WP:MOSNUM clause—and make it default. You might want to consider that as well before you start mass-producing the rest of the templates.—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 18:22, 12 March 2007 (UTC)

request for conversion: km to NM

Could someone who understands this stuff make a template for converting km to NM (nautical miles)? This would be useful in both nautical and also aerospace contexts. Thanks! Sdsds 05:46, 11 March 2007 (UTC)

You can currently use, {{subst:conv-dist|35|km|naut mi|4}} or {{convert|35|km|nmi|4}}... each also has various other formatting options. --CBD 19:28, 11 March 2007 (UTC)

Testing: {{km to NM|1|precision=4}} → . Good opportunity to learn more about templates! Rursus 13:37, 15 March 2007 (UTC)

Testing: {{NM to km|1|precision=4}} → . Rursus 13:53, 15 March 2007 (UTC)

Testing more: {{NM to km|1|precision=4|wiki=yes|abbr=no}} → and {{km to NM|1|precision=4|wiki=yes|abbr=no}} → . Errors reported here (I'll watch!). Rursus 14:02, 15 March 2007 (UTC)

Note: I didn't understand very much, template language is a nightmare even for LISP hackers, I just copy-and-pasted from Template:km to mi, then tortured the servers by previews until my mess served me the text I wanted. Rursus 16:42, 15 March 2007 (UTC)

I'm afraid it's not the template language itself but my style of writing this kind of code that gave you a headache :) Sorry about that!—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 17:01, 15 March 2007 (UTC)

Not one chance in the entire history of Universe to make readable code with a language where a variable reference to var is {{{var}}} ;^#), however proficient the template guru! Rursus 17:48, 15 March 2007 (UTC)

However unreadable it may be "under the hood," these templates rock! Check out negative values for precision: and : and . This is too cool for words. Thanks!! Sdsds 18:33, 15 March 2007 (UTC)

conversion: ly to pc

Very specialized for astronomy: {{ly to pc|4.31}} → {{ly to pc|4.31}}. Rursus 14:32, 15 March 2007 (UTC)

{{convert|4.31|ly|pc}} → "4.31 light-years (1.32 pc)". JIMp _talk·cont 13:25, 24 February 2009 (UTC)

Multiple Dimension conversion

Are there Conversion templates for two or three dimensional conversions such as sculpture measurements. I ask because I have recently created several sculpture articles including this week's WP:CHICOTW, Crown Fountain. TonyTheTiger (t/c/bio/tcfkaWCDbwincowtchatlotpsoplrttaDCLaM) 22:27, 14 June 2007 (UTC)

I'm afraid not. However, if you point me to the appropriate formulae and let me know the most convenient name for such templates, I'd be happy to create those for you. Best,—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 12:27, 15 June 2007 (UTC)

Basically, I think 2D and 3D versions of {{Ft to m}}, {{Inch}} & {{in to mm}} would be useful for most pages that use {{Infobox Sculpture}} or {{Infobox Painting}}. Crown Fountain is an example of why. A versatile one that might handle either 2 or 3 D and any of the above would be optimal. TonyTheTiger (t/c/bio/tcfkaWCDbwincowtchatlotpsoplrttaDCLaM) 16:24, 15 June 2007 (UTC)

So, just to make sure, the templates you need should look as following (or similar):

• {{3D ft to m|16|16|16}}, producing 16 ft x 16 ft x 16 ft (5 m x 5 m x 5 m)
• {{2D in to mm|6|6}}, producing 6 in x 6 in (152 mm x 152 mm)

...and you'll need them in both 2D and 3D for ft-m, m-ft, in-mm, mm-in, in-cm, and cm-in conversions; making it the total of twelve templates. All templates will have their usual parameters available (abbreviation, spelling, precision, and wiki). A universal template can certainly be created, but I think the end result will be cumersome to use, so I recommend separate templates for each type of conversion.

Please confirm if separate templates will be fine. I'll probably be able to make them next week, unless something urgent comes up. I'd also welcome ideas for better names for these templates ("2D ft to m" looks kind of weird). Best,—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 17:31, 15 June 2007 (UTC)

Actually, I've just thought that instead of separate sets of 2D/3D conversion templates, I could amend existing templates by adding a "dim" parameter. Its default value would be one (which would having to modify the templates); dim=2 would be used for two-dimensional conversions, and dim=3 — for three-dimensional. It would be possible to easily add more dimensions later should that ever become necessary. Best,—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 17:39, 15 June 2007 (UTC)

OK, after trying a few more ideas out, having the "dim" parameter turned out to be redundant. Here is what I've come up with so far:

{{ft to m|10|15}} →{{ft to m|10|15}}

Alternatively, this can be written as:

{{ft to m|l=10|w=15}} →{{ft to m}},

where "l" and "w" are, respectively, length and width. All other existing parameters (spelling, wiki, etc.) are supported, and, as an added bonus, I fixed the template to show feet in singular when "l" or "w" are equal to one:

{{ft to m|1|1}} →{{ft to m|1|1}}

Please let me know if this is going to work for you. I will then add the third dimension, and update all the templates to handle multi-dimensional conversions. Thanks.—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 21:55, 16 June 2007 (UTC)

Sorry I didn't get back. I check my talk page many times daily (except weekends). It looks like you have some great ideas. It sounds like having x parameters lead to x dimensions should work. I think the 12 you mention are sufficient if the changes can accomodate all 12 we will be in good shape. TonyTheTiger (t/c/bio/tcfkaWCDbwincowtchatlotpsoplrttaDCLaM) 15:22, 20 June 2007 (UTC)

Looking at the usage section of {{Ft to m}} you may want to try {{ft to m|10:15}} →{{ft to m|10|15}}. What do you think? TonyTheTiger (t/c/bio/tcfkaWCDbwincowtchatlotpsoplrttaDCLaM) 15:26, 20 June 2007 (UTC)

Such syntax would be very convenient, but unfortunately the template language does not currently offer capabilities to work with strings. I'd have to parse the "10:15" parameter into "10" and "15", and that's impossible until string functions are enabled across Wikimedia projects. So, we'd have to make do with multiple parameters for now.

Anyway, I hope to present one fully re-designed template for your review next week. It will support dimensional conversions, as well as range conversions. If all goes well after testing, I'll re-design the rest of the templates after the pilot one. Best,—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 16:56, 20 June 2007 (UTC)

Well, it turned out to be less work left to be done than I had thought, so {{ft to m}} is now upgraded to v. 2.0. Please test-drive it and let me know if you find any bugs or if there is anything that's not to your liking. Hopefully everything will be in order. I'll modify the rest of the templates after we are reasonably sure there is nothing seriously wrong with it; it should be a lot quicker now that there is a finished one to work with. Cheers,—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 15:30, 21 June 2007 (UTC)

(Unindent) I am wondering about the syntax. should the word by appear and then when converted be replaced with an x. Is it possible to make it optional whether the first measure uses x or by. In infoboxes (E.g., Campbell's Soup Cans) both should be x, whereas in the text such as Chicago_Board_of_Trade_Building#Permanent_home by looks better.--TonyTheTiger (t/c/bio/tcfkaWCDbwincowtchatlotpsoplrttaDCLaM) 14:28, 22 June 2007 (UTC)

Yup, you could use the "abbr" parameter. The default formatting (using "by" for the values being converted and "×" for converted values) is per WP:MOSNUM, but you could use only "×"'s by setting "abbr" to "yes", or only "by"'s by setting "abbr" to "no". All these options are described in the template documentation, actually. Let me know if there is anything else. Cheers,—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 14:53, 22 June 2007 (UTC)

There seems to be a problems with the spacing of {{Ft to m}} now. See Large Interior Form & Fountain of the Great Lakes

Sorry about that. It's one mistake I keep making. Thanks for the heads-up; I have just fixed it.—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 23:29, 23 June 2007 (UTC)

Req for converter bbl (oil) to tonne (oil)

Many oil related articles mix units with wild abandon. LeadSongDog 22:02, 31 August 2007 (UTC)

Could you, please, give an example showing how the output of such a template should look like? Also, call me stupid, but what conversion factor should be used? From what I gather it depends on oil brand or somesuch. Thanks.—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 23:02, 31 August 2007 (UTC)

Not at all obvious. I really should have elaborated. If I've got this right,

For historical reasons, "API gravity is computed as (141.5/sp g) - 131.5, where sp g is the specific gravity of the oil at 60°F." USGS

Also, 1 bbl = 42 US gallons = 0.158 987 cubic metres. The nominal division between light and heavy crude oil is 22 "degrees API gravity" at 60 degrees Fahrenheit, hence it is equivalent to a default density of 0.921824 tonnes/cubic metre. (note-API gravity increases with decreasing density). The oil industry also uses non-SI multipliers, Mbbl for 1e3 bbl, and MMbbl for 1e6 bbl.

So
{{convertcrude |1 | MMbbl | tonne | 22}}
would return a value of 1e6 * 0.158987 * 0.921824
"1 MMbbl @ 22 API (146 558 tonne)"

Thank you for your attention.LeadSongDog 22:17, 5 September 2007 (UTC)

I ain't gonna to pretend I understand how exactly this works; the important thing is that I now have the information to make the actual template :) Thanks for the explanations anyway; they've been helpful. Please give {{bbl to t}} a test run and let me know if it works the way you need it to. Once it's polished, it'll be very easy to create {{Mbbl to t}} and {{MMbbl to t}}. Also, would a template for reverse conversion ({{t to bbl}}) be of any use? What about conversions to cubic meters ({{bbl to m3}} etc.)? Thanks!—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 17:57, 6 September 2007 (UTC)

The issue is "what density of oil are you converting?" There are about 161 different types of crude oil traded internationally, and they all differ in density. The range is generally about 800 to 960 kg/m3. 22 degrees API actually marks the borderline between medium and heavy oil and is a bit heavy for this purpose. West Texas Intermediate (WTI), which is the American standard is 39.6 degrees API or about 827 kg/m3. Brent, which is the British standard is 38.3 API or about 833 kg/m3. However, that's a bit light and most crude oil is heavier than that. Which density to use? I don't know. However, I do know where the problem came from. Americans used to ship oil by volume in barrels (blue barrels, or bbl) by railway car, whereas Europeans used to ship it by weight in ships. (The Brits used either long tons or short tons, while the French used metric tonnes, but lets gloss over that issue.) RockyMtnGuy 06:45, 10 September 2007 (UTC)

Don't look at me, I'm just a guy who made a tool according to the provided specifications :) If there is a way to make the template useful (by including lookup values tied to density, maybe?), just let me know, I'll make the modifications. If there is no workable solution, we might just as well delete {{bbl to t}} altogether.—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 17:23, 10 September 2007 (UTC)

Don't think you're not appreciated, and thanks for the clarification. I had rather hoped that by giving the API gravity as a parameter, the density could be calculated, hence the volume to mass equivalence. (Sidenote: Anyone who grasps Archimedes Principle will get the importance to ships' masters of knowing the mass loaded. The concept of a compressible fluid in a tanker is a little more difficult, but explains why they also need to know volumes.) But to the point, I'd eventually like to see a way that presentation skins recognize the converters and show the form the reader understands best.LeadSongDog 17:28, 10 September 2007 (UTC)

Don't panic! Why don't you use the same conversion factor that BP uses in its Statistical Review of World Energy? That happens to be 0.1364 (see http://www.bp.com/extendedsectiongenericarticle.do?categoryId=9017944&contentId=7033505). According to my calculations, that corresponds to an oil density of about 0.858 tonnes/m3, which corresponds to an API gravity of about 33.4 degrees, which sounds pretty average for crude oil in my experience. If you want to convert API gravity to Density, use Density = 141.5/(API+131.5). The issue here is not compressibility, crude oil not being very compressible, it's the variable composition. Some crude oil is as light as gasoline, some of it is thicker than molasses and heavier than water. The fact that it's only an average figure probably should be noted in the documentation. And you're quite right, the captain wants to know how heavy the crude is so he doesn't inadvertently sink the ship while loading it. RockyMtnGuy 19:49, 10 September 2007 (UTC)

Actually, it's Specific Gravity = 141.5/(API+131.5). S.G. (or "relative density") is a unitless measure comparing the density of a sample to the density of water at given temperatures. While the two are very close in actual value IF the temperatures are the same (e.g. Specific Gravity 20/20 or 15/15) they are not interchangeable. —Preceding unsigned comment added by 209.19.30.58 (talk) 20:54, 20 August 2008 (UTC)

The difference is academic. Water at 60°F, which the API definition of S.G. is based on, weighs 999 kg/m³, close enough to 1000 kg/m³ (1 tonne/m³) for most practical purposes. S.G. is a rather archaic unit in any case and density in SI units is more modern.RockyMtnGuy (talk) 02:31, 21 August 2008 (UTC)

Thanks! I changed {{bbl to t}} to use the conversion factor of 0.1364. You are welcome to edit the template's documentation to mention all things that need to be mentioned (I feel rather uncomfortable documenting such very specific points which I know next to nothing about). If you need to have the output tweaked in some manner, I'll be happy to help with the template's actual code. Best,—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 20:17, 10 September 2007 (UTC)

Thank you. It's usable with a fixed conversion factor, but I'd suggest either explicitly outputing for example "approximately 395 tonnes", limiting ouput to no more than 3 significant digits, or (preferably) requiring an input value for API gravity (density would provide the needed information, as they're mutually convertible representations of the same physical property, but API is the more usual reference).LeadSongDog 22:07, 10 September 2007 (UTC)

I hope I got it right this time. Please check {{bbl to t}} once again. You can now specify the API factor (and if you don't, the default of 33.4 will be used). The conversion is done as follows: OutputInTonnes=bbl*.158987*141.5/(API+131.5). As for the significant digits, it is rather tricky to implement those, but you can use the precision parameter to regulate the precision of the output manually (by default, the precision of zero is used). Also, do you need the actual API/density to show in the output? If so, what would be the best place for it?—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 15:27, 11 September 2007 (UTC)

That looks just great to me. Thank you. To address your earlier question, yes, the barrel to cubic metre converter and the reciprocal converters would also be useful. Style calls for first identifying the quantity in the units used in the cited source, so different cites require different directions of conversion.LeadSongDog 17:30, 11 September 2007 (UTC)

You are welcome. I'll make an announcement in this thread when the rest of the templates are complete (it may take me a while though). Also, are there any fine points I should be aware of when converting barrels to cubic meters?—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 17:40, 11 September 2007 (UTC)

Just what it says at Barrel (unit) and at the NIST page cited there. LeadSongDog 21:45, 11 September 2007 (UTC)

Currency conversion templates

Is there any interest to create currency conversion templates ? They would have the complication of varying conversion factors. The template for the latest factor must be updated. There could be a wish for historic factors, for example in an article about a previously built building, bridge, airport etc. If they are located outside the USA, it could be good to have the cost in local currency plus US$ with an easy conversion template. -- BIL 16:35, 30 September 2007 (UTC)

I'm not sure this would be especially helpful. If something was built outside of the US, it is straightforward enough to use then-current exchange rate to convert between local currency and the U.S. dollars, but for older buildings there is still an issue of converting these amounts to modern dollars. The way I see it, one needs reliable sources to back up this kind of conversion anyway, so for cases where currency conversion is helpful it would be easier to just type in the amount by hand instead of using a conversion template. As for only keeping track of the most recent exchange rate, relying on one person (or even on a group of people) constantly updating the rates for the template does not sound as a good way to handle this–there'll always be slips, typos, or missed updates.—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 13:54, 1 October 2007 (UTC)

List needed

Please see Wikipedia talk:Template messages#Needs direct link to conversion templates, wherein an editor (essentially) requests a list page of all the conversion templates, for easier browsing of them all. Thanks. --Quiddity 17:23, 1 October 2007 (UTC)

Hyphens

Does anyone know if there's a switch in the conversion templates for including/not including the hyphen between number and unit? WP:HYPHEN seems to mean that a hyphen is needed for '3-litre engine', but not for 'an engine of 3 litres'.

Alternatively, where're the instructions for these templates? Thanks. 4u1e 18:09, 1 October 2007 (UTC)

I am not aware of any existing conversion template with a hypen switch; one would basically have to re-word sentences as in your example above in order to use the conversion templates. A hyphen switch would be a good feature to add, however. As for the instructions, if you click on any conversion template in the category listing, you will see them (note, however, that a few of the templates are not properly documented and some may have instructions on their talk pages).—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 19:31, 1 October 2007 (UTC)

Thanks. I can't re-word for the article I'm working on (or I could, but the sentences would be much the worse for it!). I can of course just do it by hand instead, but I thought I'd ask. Re: instructions - looks like I was unlucky. Neither of the templates I'm interested in (litres and in) have instructions. 4u1e 21:21, 1 October 2007 (UTC)

Use {{convert}}, {{convert|3|l|adj=on}}, for example, gives "3-litre (0.66 imp gal; 0.79 US gal)". Jɪmp 03:51, 15 January 2008 (UTC)

Basic

I suggest as much as possible conversion templates be based in template:convert --Mac (talk) 08:26, 5 February 2008 (UTC)

I second this. Moreover, I propose that no more new templates be added to the category if their function could be covered by {{convert}}. Jɪmp 01:27, 26 March 2008 (UTC)

Error

{{convert|1|in|mm}} produces 1 inch (25 mm) instead of 1 inch (25.4 mm). 92.50.83.23 (talk) 04:00, 30 December 2008 (UTC)

It's not an error, it's by design. See the "default rounding" section of {{Convert}}'s documentation.—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 14:46, December 30, 2008 (UTC)

Force

Could there be a conversion template from lbf to N ??? Hektor (talk) 08:28, 8 July 2009 (UTC)

{{Convert}} supports it: {{Convert|20|lbf|N}}→20 pounds-force (89 N).—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); 13:35, July 8, 2009 (UTC)

2 for 1 special

Is there a way to add both km & sm in the template for ship's endurance? I've seen it convert km to nmi, but it broke on trying to add smi. Also, is there a way to convert °C to °F back & forth, when I want the number of degrees difference, & not the temperature? TREKphiler ^{any time you're ready, Uhura} 22:34, 30 November 2011 (UTC)

• multiple units return: make a list, space-separated:

{{convert|200|nmi|km mi}} → 200 nautical miles (370 km; 230 mi)

• change of temperature: use C-change etc:

{{convert|10|F-change|C-change}} → 10 °F (5.6 °C)

• See more on {{Convert}} (talk). -DePiep (talk) 10:25, 14 September 2019 (UTC)