Understand how clinical thermometers work, normal body temperature ranges, and temperature scales (Celsius, Fahrenheit, Kelvin).
Preview · progress not saved — Chapter 1 is free
Fact about replacing mercury thermometers.
Definition and usage of clinical thermometers.
The normal temperature of a healthy human body is widely known to be 37.0 °C (or 98.6 °F).
However, this isn't an absolute rule for everyone! What we call "normal" is actually the average body temperature calculated from a large number of healthy people. Your personal normal might be slightly higher or lower depending on your age, activity level, and the time of day.
Labeled diagram of a digital thermometer.
Modern digital thermometers use heat sensors instead of toxic mercury to measure body temperature safely.
Explanation of Celsius, Fahrenheit, and Kelvin scales.
Scientists have developed three main scales to measure how hot or cold a body is. The two you are most likely to encounter in daily life are the Celsius scale and the Fahrenheit scale.
Both scales use the word "degree" as their unit, denoted by a small circle (°). For example, a healthy human body has an average temperature of 37.0 °C, which is exactly equal to 98.6 °F.
Visual comparison of human body temp across three scales.
Notice that the Kelvin scale does not use a degree (°) symbol.
Warning about using clinical thermometers outside their range.
Flashcards for key terms introduced in this section.