# Why is our body temperature 98.6 degrees? **URL:** \ **Category:** Factual Questions\ **Created:** [December 9, 2009, 9:00pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633 "2009-12-09T21:00:20Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Dandmb50](https://avatars.discourse-cdn.com/v4/letter/d/ba9def/32.png) [@Dandmb50](https://boards.straightdope.com/u/Dandmb50)\ **Post date:** [December 9, 2009, 9:00pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/1 "2009-12-09T21:00:20Z")
Always wondered why our body temperature is 98.6 degrees, did we not do the calculations for temperatures correctly from the beginning? Why isn’t it 90 or 100 or something even? It’s just such an odd number. What would it be in metric measurement? Maybe that’s what is wrong. Or is it the same all over the [world?](http://i78.photobucket.com/albums/j83/dandmb50/DSC_0026-3.jpg) Huh? ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [December 9, 2009, 9:05pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/2 "2009-12-09T21:05:44Z")
98.6 F works out to precisely 37 C. I’ve heard that 37 C was the value that had been measured in Europe, and that they simply converted directly using the (9/5) C + 32 formula. The 98.6 does seem a bit too precise, given that there are only two significant digits in that 37. And human body temperature does vary a bit. edited to add: See here, under _History_ > **[Human body temperature](https://en.wikipedia.org/wiki/Normal_human_body_temperature)** > > Normal human body-temperature (normothermia, euthermia) is the typical temperature range found in humans. The normal human body temperature range is typically stated as 36.5–37.5 °C (97.7–99.5 °F). > Human body temperature varies. It depends on sex, age, time of day, exertion level, health status (such as illness and menstruation), what part of the body the measurement is taken at, state of consciousness (waking, sleeping, sedated), and emotions. Body temperature is kept in the normal range by a h... ---
**Author:** ![Rigamarole](https://avatars.discourse-cdn.com/v4/letter/r/77aa72/32.png) [@Rigamarole](https://boards.straightdope.com/u/Rigamarole)\ **Post date:** [December 9, 2009, 9:11pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/3 "2009-12-09T21:11:08Z")
Yeah, it’s not really 98.6 at all. There are significant variations from person to person, and studies usually put the true average slightly lower than that. I think it is just a byproduct of someone converting 37 C into Fahrenheit. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [December 9, 2009, 9:14pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/4 "2009-12-09T21:14:31Z")
[Cecil has written everything you’d ever want to know about it.](http://www.straightdope.com/columns/read/845/on-the-fahrenheit-scale-why-is-32-freezing-and-212-boiling) ETA: It’s pretty impressive when you Google “farenheit origin” and Cecil’s column ranks first 🆒 ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [December 9, 2009, 9:14pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/5 "2009-12-09T21:14:40Z")
It was originally 96 and/or 98 in Fahrenheit > **[Fahrenheit](https://en.wikipedia.org/wiki/Farenheit)** > > The Fahrenheit scale (/ˈfærənˌhaɪt, ˈfɑːr-/) is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit (symbol: °F) as the unit. Several accounts of how he originally defined his scale exist, but the original paper suggests the lower defining point, 0 °F, was established as the freezing temperature of a solution of brine made from a mixture of water, ice, and ammonium chloride (a salt). The other limit estab For m... ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [December 9, 2009, 9:16pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/6 "2009-12-09T21:16:54Z")
The original intention was that the zero point of the Fahrenheit scale be the freezing point of a concentrated brine, the lowest temperatore that could be reliably created at the time, and the 100 degree point be body temperature. After the scale was established, finer calculations showed that normal body temperature was something over a degree F below the 100 mark that had been established. Keeping the freezing-to-boiling point for water at exactly 180 degrees seemed more useful to the scientists calibrating it than making the exact value of body temperature an even number. Hence the 98.6 degrees temperature for the average body temperature of an average healthy human being (many people’s norm is above or below the 98.6 value by up to a degree or so). ---
**Author:** ![Bad\_Astronaut](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@Bad\_Astronaut](https://boards.straightdope.com/u/Bad_Astronaut)\ **Post date:** [December 9, 2009, 9:18pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/7 "2009-12-09T21:18:12Z")
> [@Dandmb50](#): > > Always wondered why our body temperature is 98.6 degrees, did we not do the calculations for temperatures correctly from the beginning? Why isn’t it 90 or 100 or something even? It’s just such an odd number. What would it be in metric measurement? Maybe that’s what is wrong. Or is it the same all over the [world?](http://i78.photobucket.com/albums/j83/dandmb50/DSC_0026-3.jpg) > > Huh? Edit: Polycarp’s post defeated mine. Interesting point about the strangely precise value of 98.6 being common knowledge, I never thought about it but people really might as well just say it’s 99. ---
**Author:** ![lisiate](https://avatars.discourse-cdn.com/v4/letter/l/f05b48/32.png) [@lisiate](https://boards.straightdope.com/u/lisiate)\ **Post date:** [December 9, 2009, 9:20pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/8 "2009-12-09T21:20:01Z")
When Fahrenheit originally defined his scale he defined body temperature as 96 degrees, giving him 64 degrees between freezing and body temperature (and making the subdivisions easier to mark on his thermometer). The scale was later revised so that there would be exactly 180 degrees between water freezing and boiling, this moved the body temperature point to about 98 degrees. (largely cribbed from the wikipedia article on [Fahrenheit](http://en.wikipedia.org/wiki/Fahrenheit)) ---
**Author:** ![cwthree](https://avatars.discourse-cdn.com/v4/letter/c/9de0a6/32.png) [@cwthree](https://boards.straightdope.com/u/cwthree)\ **Post date:** [December 9, 2009, 10:51pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/9 "2009-12-09T22:51:32Z")
This all explains why the Fahrenheit scale places the average body temperature where it does. But I have a related, but different question: Why is the human body temperature what it is (allowing for normal variation)? Other animals (cats, for instance) have a normal body temperature that’s significantly higher, on the average, even allowing for some variation. ---
**Author:** ![alphaboi867](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alphaboi867/32/3898_2.png) [@alphaboi867](https://boards.straightdope.com/u/alphaboi867)\ **Post date:** [December 9, 2009, 11:44pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/10 "2009-12-09T23:44:22Z")
> [@Rigamarole](#): > > Yeah, it’s not really 98.6 at all. There are significant variations from person to person, and studies usually put the true average slightly lower than that. I think it is just a byproduct of someone converting 37 C into Fahrenheit. My normal body temp is only 97 degrees. Mom said it runs in the family. ---
**Author:** ![Super\_Kapowzler](https://avatars.discourse-cdn.com/v4/letter/s/a698b9/32.png) [@Super\_Kapowzler](https://boards.straightdope.com/u/Super_Kapowzler)\ **Post date:** [December 9, 2009, 11:51pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/11 "2009-12-09T23:51:22Z")
You are all WRONG. But that’s OK, because we are all human. 98.6 comes from a song that went something like “Hey 98.6, it’s good to have you back again…” The song was good, and easy to remember, so that is where 98.6 comes from. If you have any other questions, let me know, I’m about to break out some old 33 1/2 records to research things further. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [December 10, 2009, 1:54am UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/12 "2009-12-10T01:54:12Z")
> [@alphaboi867](#): > > My normal body temp is only 97 degrees. Mom said it runs in the family. In the morning until around 11 or so mine is under 97. Normally around 96.5. Love going to DR or giving blood in the morning. I always get the are you felling OK? ---
**Author:** ![GoodOmens](https://avatars.discourse-cdn.com/v4/letter/g/d26b3c/32.png) [@GoodOmens](https://boards.straightdope.com/u/GoodOmens)\ **Post date:** [December 10, 2009, 2:34am UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/13 "2009-12-10T02:34:33Z")
I’m confused about the picture linked in the original post. Does it bear any relevance to the content of the post, other than being a random picture of a foreign person? ---
**Author:** ![Bad\_Astronaut](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@Bad\_Astronaut](https://boards.straightdope.com/u/Bad_Astronaut)\ **Post date:** [December 10, 2009, 4:09am UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/14 "2009-12-10T04:09:46Z")
> [@Dandmb50](#): > > Or is it the same all over the [world?](http://i78.photobucket.com/albums/j83/dandmb50/DSC_0026-3.jpg) > > Huh? It’s a picture of someone from the world! Maybe she owns some [possessions](http://farm4.static.flickr.com/3115/3253264935_5a1b5a9aac.jpg). ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [December 10, 2009, 4:12am UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/15 "2009-12-10T04:12:56Z")
I thought we were nominally 310ºK. ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [December 10, 2009, 4:19am UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/16 "2009-12-10T04:19:15Z")
> [@cwthree](#): > > This all explains why the Fahrenheit scale places the average body temperature where it does. > > But I have a related, but different question: Why is the human body temperature what it is (allowing for normal variation)? Other animals (cats, for instance) have a normal body temperature that’s significantly higher, on the average, even allowing for some variation. Probably because they have a faster metabolism in general. ---
**Author:** ![Bad\_Astronaut](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@Bad\_Astronaut](https://boards.straightdope.com/u/Bad_Astronaut)\ **Post date:** [December 10, 2009, 4:27am UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/17 "2009-12-10T04:27:35Z")
> [@Der\_Trihs](#): > > Probably because they have a faster metabolism in general. But presumably there must be some evolutionary adaptation at play. I assume body temperature is optimized for the various chemical reactions that need to occur in the body and maybe for other things as well. So the question is, what is different in a Cat’s body or lifestyle that makes a different temperature advantageous? ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [December 10, 2009, 4:32am UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/18 "2009-12-10T04:32:59Z")
> [@Bad\_Astronaut](#): > > But presumably there must be some evolutionary adaptation at play. I assume body temperature is optimized for the various chemical reactions that need to occur in the body and maybe for other things as well. So the question is, what is different in a Cat’s body or lifestyle that makes a different temperature advantageous? This reminds me of my high school biology class, when the question was asked why humans couldn’t be the size of elephants. The answer was that if we were, we’d overheat and die. I wondered, but didn’t ask, ‘Well, if we were the size of elephants, wouldn’t we have evolved in such a way that temperature would not be an issue?’ ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [December 10, 2009, 5:51pm UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/19 "2009-12-10T17:51:08Z")
> [@Bad\_Astronaut](#): > > But presumably there must be some evolutionary adaptation at play. I assume body temperature is optimized for the various chemical reactions that need to occur in the body and maybe for other things as well. So the question is, what is different in a Cat’s body or lifestyle that makes a different temperature advantageous? I recommend reading through this paper: [Scaling of body temperature in mammals and birds](http://www3.interscience.wiley.com/cgi-bin/fulltext/119401426/PDFSTART) (.pdf doc). Per the abstract: > [@](#): > > This study indicates a complex relationship between body mass, body temperature and metabolic rate in mammals and birds, mediated through ecology. ---
**Author:** ![Indian](https://avatars.discourse-cdn.com/v4/letter/i/c0e974/32.png) [@Indian](https://boards.straightdope.com/u/Indian)\ **Post date:** [January 1, 2011, 8:35am UTC](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633/20 "2011-01-01T08:35:50Z")
> [@cwthree](#): > > This all explains why the Fahrenheit scale places the average body temperature where it does. > > But I have a related, but different question: **Why is the human body temperature what it is (allowing for normal variation)?** Other animals (cats, for instance) have a normal body temperature that’s significantly higher, on the average, even allowing for some variation. \*\*Our standard body temperature strikes a perfect balance between maintenance of our metabolism and resistance to fungal infection.Humans and other advanced mammals are very hot compared with other animals. \*\*. From the sturdy of Arturo Casadevall, M.D., Ph.D., professor and chair of microbiology & immunology at the Albert Einstein College of Medicine of Yeshiva University. [Link](http://www.ts-si.org/biology/28221-standard-human-temperature-provides-immunity) [Next page](https://boards.straightdope.com/t/why-is-our-body-temperature-98-6-degrees/520633.md?page=2)