Rectal, ear, oral, and axillary temperature comparison

To determine whether a fever is present, an accurate body temperature is needed. Medical research has not determined an exact correlation between oral, rectal, ear (tympanic), and armpit (axillary) temperature measurements. Generally, the correlation of temperature results are as follows:

• The average normal oral temperature is 98.6°F (37°C). An oral temperature is 0.5°F (0.3°C) to 1°F (0.6°C) lower than a rectal or ear (tympanic) temperature.
• 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 temperature.
• An armpit (axillary) temperature 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.
• The manufacturer of the temperature device you use, such as a tympanic 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 are not 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 health professional 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 the topic Body Temperature.

The temperature comparison table lists only the temperature ranges found in the questions in the Check Your Symptoms section of the Fever topics so that you can answer the questions accurately.

Rectal temperature guidelines are used in Fever, Age 3 and Younger.

Oral temperature guidelines are used in Fever, Age 4 and Older.

To use the table:

• Find the method that you used to take a temperature.
• Find the correct temperature range.
• See the correlating rectal or oral temperature range to help you answer the Check Your Symptoms questions.
  • For example, in Fever, Age 3 and Younger: 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, measured rectally.
  • For example, in Fever, Age 4 and Older: If your axillary temperature is 100°F (37.8°C), your oral temperature is about 101°F (38.3°C).

Comparison of temperatures in Fahrenheit by method

Axillary (°F)	Oral (°F)	Rectal/Ear (°F)
98.4–99.4	99.4–99.9	100.4–100.9
100–101	101–101.5	102–102.5
101–102	102–102.5	103–103.5
102–103	103–103.5	104–104.5
103–104	104–104.5	105 or 105.5

Comparison of temperatures in Centigrade by method

Axillary (°C)	Oral (°C)	Rectal/Ear (°C)
36.9–37.4	37.4–37.7	38–38.3
37.8–38.3	38.3–38.6	38.9–39.2
38.3–38.9	38.9–39.2	39.4–39.7
38.9–39.7	39.4–39.7	40–40.3
39.4–40	40–40.3	40.6–40.8