What is a normal temperature for an adult?

Written by meaghan ringwelski | 13/05/2017
What is a normal temperature for an adult?
The average temperature becomes useful knowledge when you're feeling ill. (Getty Images)

Taking the body temperature of an adult is one of the most basic ways of determining her general health. As one of the primary vital signs, body temperature is a standard gauge used in medicine. Knowing normal and abnormal body temperatures is important in properly reading and interpreting the results when using a thermometer.

Normal temperature

In grown adults, a normal temperature can range from 36.5 to 37.2 degrees Celsius, or between 97.8 and 99 Fahrenheit. As long as the results of a thermometer fall within this range, it can be determined that a person's body temperature is normal.


When an adult's body temperature is above the normal range, he or she is considered to have a fever. Medically speaking, a fever is present with temperatures above 37 degrees Celsius (98.6 Fahrenheit) with an oral thermometer or above 38.7 degrees Celsius (99.8 Fahrenheit) with a rectal thermometer.

Types of fevers

When a person has a fever, it is usually due to an abnormal process that is occurring within the body. Often it is caused by the body's natural defence mechanisms as it attempts to fight off disease. A very high fever, however, does not necessarily indicate a serious condition. The common flu can generate fevers as high as 40 degrees Celsius (104 Fahrenheit).


Hypothermia is a much rarer occurrence. Temperatures below 35 degrees Celsius (95 Fahrenheit) are considered to be in the range of hypothermia. This condition does not occur on its own, but usually when a person is subjected to extreme cold for a prolonged period of time.


When taking body temperature, it is important to bear in mind that different methods yield different results. The normal range discussed above refers to temperatures taken with oral thermometers. If a temperature is taken rectally, the results will be about 0.3 to 0.4 degrees Celsius (0.5 to 0.7 Fahrenheit) higher. Temperatures taken under the arm usually generate results that are 0.17 to 0.22 degrees Celsius (0.3 to 0.4 Fahrenheit) lower. These subtleties must be kept in mind when interpreting the results of a thermometer reading.

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