It’s Gettin Hot in Here…

Posted: 13 August, 2007 in Science

I was recently sitting and diligently doing my Physics, which, at the moment, is covering thermodynamics. When I came to a short section on thermometers, I allowed my mind to wander off on tangents like “What’s the normal body temperature of a human?” and “How much can that deviate from the normal before you are considered to have a ‘temperature”. Bringing myself back to the task at hand, I resolved to research to topic during my break. I’m not sure how often our “resident orthopod” reads the blog, but perhaps he could correct my youthful mistakes and add his knowledge when he comments?

Well, first off – What is the average body temperature of a human being?

That one was super easy to find. Our ‘normal’ temperature is considered to be 98.6 ºF or 37 ºC
However, this varies depending on what part of the anatomy you take the temperature:

Oral = 37 ºC Axillary (armpit) = 36.4 ºC
Rectal (if you dont know where that is… dont ask) = 37.6 ºC
Tympanic (ear canal) = 37.6 ºC

Oral readings are by far the most convenient. Axillary readings or readings taken between two folds of skin take the longest to obtain and are by far the least accurate. And rectal readings are the most accurate (since you are taking internal temperature) but on the flip side, they’re inconvenient and generally considered to be a pain in the …. Tympanic readings are just as accurate as their rectal counterparts, and very quick, but a special tympanic thermometer is necessary in order to obtain it.

As I said above, your BT can vary by around a degree depending on the time of day, hormone levels, metabolism and muscular activity. It is for this reason that temperature should always be taken only after a person is relatively rested.

What is a fever?

A rectal or otic temperature which is higher than 38 ºC
An oral temperature higher than 37.5 ºC
An axillary temperature higher than 37.2 ºC

However, these readings need to be interpreted in the light of the above mentioned factors which influence BT.

Fevers can be classified as follows:

Low-grade = 38-39 ºC
Moderate = 39-40 ºC
High grade = > 40 ºC
Hyperpyrexia = > 42 ºC (If your temperature ever reads this high and you are still conscious… your thermometer is broken 😀 )

Fevers are just one of the amazing defence mechanisms that the body uses to fight disease. Elevated or lowered BT causes unbearable conditions for pathogens and hinders their growth and harmful activity, while allowing white blood cells (leukocytes) to proliferate and function well in ideal conditions.




  1. Salomé says:

    Whoa, that’s interesting Antz! You seem to be indulged in scientific matters. When it comes to science, I’m forever grateful I’m down with school. Haha…
    Take care and have a blessed day!

  2. Jessa says:

    Wow thanks Ant. Sometimes I lie awake at night wondering what the specifics of body temperature are. Now I can rest in peace 🙂 But seriously, that really is interesting. I never knew that fevers are a body’s way of fighting bad germs.

  3. Neil says:

    Just one comment. There are different thermometers for measuring the temperature at the different sites. NEVER mistake the rectal thermometer for the oral!

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