You can take a temperature using the mouth (oral), anus (rectal), armpit (axillary), or ear (tympanic). But the temperature readings vary depending on which one you use, and you need an accurate body temperature to determine if a fever is present.
Medical research hasn't determined an exact correlation between
oral, rectal, ear, armpit, and forehead temperature measurements.
Generally, the correlation of temperature results are as follows:
The average normal oral temperature is
A rectal temperature is 0.5°F (0.3°C) to
1°F (0.6°C) higher than an oral temperature.
An ear (tympanic) temperature is 0.5°F (0.3°C) to 1°F (0.6°C) higher than an oral
An armpit (axillary) temperature is usually 0.5°F (0.3°C) to 1°F (0.6°C) lower than an oral temperature.
A forehead (temporal) scanner is usually 0.5°F (0.3°C) to 1°F (0.6°C) lower than an oral temperature.
It is important to remember:
Rectal temperatures are generally thought to be
the most accurate for checking a young child's temperature.
manufacturer of the temperature device you use, such as an ear or forehead thermometer,
provides information on how to use it. Be sure to read and follow the
instructions to obtain an accurate temperature. The information may also
include how the results of the device correlate with the results from other
methods of taking a temperature.
Plastic strip thermometers have
some uses, but they aren't recommended for general home use. Unlike oral,
rectal, and ear thermometers, plastic strip thermometers measure skin
temperature, not body temperature.
When you talk with your doctor about your temperature,
be sure to say what method was used to take the temperature.
Temperature comparison table
The temperature comparison table below will give you the range of
temperature correlation with the different methods used to take a temperature.
For information about taking accurate temperatures in infants and children, see
To use the table:
Find the method that you used to take a
Find the correct temperature range.
Look for the temperature range of the other methods that correlates to the method you used.
If your 2-year-old child's oral temperature is
101°F (38.3°C), his or her
rectal or ear temperature may be about
102°F (38.9°C). Remember, a
child has a fever when his or her temperature is
100.4°F (38°C) or higher,
axillary temperature is
100°F (37.8°C), your oral
temperature is about
Comparison of temperatures in Fahrenheit by method
Comparison of temperatures in Centigrade by method
How this information was developed to help you make better health decisions.