Talk:Calorie

"Calorie" in widely used Nutritional Information Labeling
I'll bet you that the most visitors to this page are people that see "Calories" on their food-nutrition labels and come to Wikipedia to get an explanation. But, what they'll see is multisylabic, ambiguous, and unfathomable.

Instead, there needs to be a plain statement about how the label "Calories" on food labels is a Popular Misnomer; although Nutrition Labeling uses the term "Calories" for simplicity, the numbers on the labels are actually the number of kcalories; for example, 100 Calories on food labeling is actually (scientifically) 100 kcalories; some of us might prefer if food labeling were more accurate by providing the correct unit "kcalorie," but with the momentum toward making food labeling "easier," that is probably not going to happen; just as long as interested parties understand that food labeling actually lists the number of kcalories.

Even my rendition is a bit long winded, but if you're fighting against a popular misnomer, it takes an extra couple of lines to set the record straight.

Then, they can read the rest of the article to find out what a kcalorie is.

-neil- 98.21.60.222 (talk) 14:01, 6 February 2014 (UTC)


 * As far as I'm aware the calorie was first defined as the amount of heat needed to heat a kilogram of water through 1 °C. Somewhere along the line someone decided to redefine it using one gram instead.  So there were a big one and a small one. Scientists wound up preferring the small one. I suppose this was done for convenience but the big one is more convenient for food energy. So which one is correct? Just because the small one was preferred by scientists doesn't make it better.  That would be a weak argument and even weaker considering that most scientific areas have dropped the unit in favour of the SI (perhaps it's still useful in some areas of chemistry). So is the kilocalorie the "correct unit" (as suggested) or is the calorie correct? Neither, the best unit is the kilojoule. Jimp 09:55, 7 February 2014 (UTC)
 * A calorie is not the same thing as a Calorie. If a calorie used to be 1000 grams of water heated to 1 Celsius earlier is now irrelevant as the current definition is 1 gram heated to 1 Celsius. The redefinition was most likely use to avoid mixing prefixed and non-prefixed units. And keep it in line with other measures for simplicity sake. And to use a definition on the base unit, not a prefixed one. As I understand it, it seems that mostly the US uses Calories instead of kcalories for food labels and that Calories and calories are not the same thing.So one Calorie equals one Kcal which equals 1000 calories. — Preceding unsigned comment added by 62.13.26.84 (talk) 08:17, 24 November 2017‎ (UTC)

Sentence removed: dead-link ref
The sentence below was removed because is its dubious, and the only reference given is an URL with no title that is now dead: "However, it is the convention not to use the calorie without specifying the value in Joules for universal clarity.  This may be a recommendation by some teachers, books, or official bodies; but it does not seem to be a convention AFAIK. The scientists who still use kcal do not seem to care about it; and presumably those who care will use only joules. --Jorge Stolfi (talk) 04:51, 24 February 2013 (UTC)

Conversion factors & the specific heat capacity of water
This edit replaced this

"The factors used to convert calories to joules are numerically equivalent to expressions of the specific heat capacity of water in joules per gram or per kilogram."

with this.

"The factor used to convert calories to joules is equivalent to the specific heat capacity of water expressed in joules per Kelvin per gram or per kilogram."

Jimp 09:34, 3 March 2014 (UTC)
 * The word "kelvin" should be lower case.
 * There are in fact various different factors depending on the temperature.
 * It is a numerical equivalence. The conversion factor is ~4.2 J/cal (kJ/kcal or kJ/Cal) but this is one. The specific heat capacity of water is not one it's ~4.2 J/(K·g). The number is the same but the units are not.

Missing information: Which calorie is most widely used today?
I cannot find information about which definition of the calorie is "up-to-date" and thus to be used (or most widely used) today. From several sources I believed that the international steam table calorie, but with an exact value of 4.1868 (modern) joules is the "official" one (the double quotes due to the fact that the joule is the official resp. SI unit), but this and the corresponding German WP article (except for its introduction which favours the 4.1868 J figure) seam to suggest that the thermochemical calorie seems to be slightly "more official". BTW I know that the differences are far smaller than the uncertainties typically occurring in e.g. nutrition analysis.--SiriusB (talk) 05:53, 11 October 2014 (UTC)


 * The calorie is a bit like the mile. There are more "official" definitions of each than there are fingers on both of your hands.  If you want to make a precise statement, it is wise to avoid them. Dondervogel 2 (talk) 07:35, 11 October 2014 (UTC)


 * C'mon, "T-bird II", the question was about "common". Unless a standard is specified, you are counting on your audience to rely on their own knowledge or intelligence, and either rely on SI or their (good or bad) intuition. If you're talking food, you can surely count on the public misperception that "calorie" really means, well, uh, you know, what "everybody", the ignorant "man in the street" "KNOWS" it means. Perhaps that means that our article is inadequate, and that we have found a clear exception (perhaps worthy of mention there) to what I recall as implicit in our WP:Dab policy: that confusing usage of some terms is so rampant that prevalence of usage needeth-to-be-damned in their respective cases. A Modest Proposal: The WP:HATNOTE markup

accompanying this article is grossly inadequate, primarily because the primary use of the term, at least in American usage, is a misusage in light of the *popularization* of the technical term as a handy shorthand for what would more logically be called "nutritional calorie". WP:NOTADICT (am I repeating myself, bcz of an aging brain and my misapplication of the unsuitable iPad ii to the task of editing WP?), but WP:IAR. --Jerzy•t 05:44, 11 March 2019 (UTC)

Oops, needs another edit to correct formatting error Jerzy•t 05:47, 11 March 2019 (UTC)

The One & Only Calorie With An Exact kWh Equivalent
Some time ago, I corrected the article, setting the International Steam Table calorie (1956) exactly equal to 1.163 mWh, by merely replacing the wavy equal sign "≈" with the regular "=" sign. This pleasant feature may be the reason why it is the calorie preferred by dieters, as kilocalorie: 1 Cal = 1.163Wh. So Russ Rowlett in his former UNC tables of constants. This may have been the shortest possible Wikipedia edit, ever...!! hgwb 12:25, 11 March 2019 (UTC)

National differences
My observation is that in the US the kilocalorie is officially preferred (e.g. in product labelling), whereas in Australia there is an official preference for the kilojoule (although the kilocalorie is still widely used, especially due to the pervasive US influence on Australian culture and businesses.) I think some discussion of national differences in the use of energy units (at least in the field of food, exercise and nutrition) would be a valuable addition to the article. SJK (talk) 09:47, 28 May 2020 (UTC)

Calorie = 4.1868 J in the EU
In the European Union
 * 1) the official unit is joule
 * 2) calorie may be on the label (only) in addition. In this case, "calorie" is always the small calorie, i.e. 4.1868 J. This has been fixed by EU law in 1971 . Hence 4186.8 J is "kcal" and only "kcal" -- Wassermaus (talk) 20:55, 3 July 2020 (UTC)