Taking a temperature: What am I measuring?

Taking a temperature: What am I measuring?

When you take a temperature, you are trying to measure how hot your child is inside their body. This is called their 'core temperature'.

When you take a temperature, you are trying to measure how hot your child is inside their body. This is called their 'core temperature'.

You measure the temperature in places that are closest to the inside temperature. You measure the temperature either:

  • inside the mouth (oral), or
  • under the arm (axillary), or
  • in their outer ear canal (tympanic)

In hospital, temperatures are sometimes measured in the bottom (rectal). We advise that you do not take your child's rectal temperature at home.

The normal temperature inside your child's body is around 37 degrees Celsius. Your child's brain helps control their core temperature and to keep it around that level. After 3 months of age, body temperature changes with a daily rhythm - rising to 37.3 toward the end of daytime before dropping to 36.8 shortly after going to sleep at night and then slowly coming up to about 37 in the morning. New babies are not as good at controlling their temperature as older children.

We say that there is a fever when the temperature is more than 38 degrees Celsius. A fever by itself does not indicate whether your child is seriously sick or not.

This page last reviewed 24 November 2015.
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