What Is a Normal Temperature for an Adult?

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 97.8°F to 99°F, or between 36.5°C and 37.2°C. 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 98.6°F with an oral thermometer or above 99.8°F 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 defense 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 104°F.


Hypothermia is a much rarer occurrence. Temperatures below 95°F 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 0.5 to 0.7° higher. Temperatures taken under the arm usually generate results that are 0.3 to 0.4° lower. These subtleties must be kept in mind when interpreting the results of a thermometer reading.