As a general rule, a temperature of over 37.5C (99.5F) is classified as a fever in children.
But this can vary from child to child. Some children may be ill with a lower temperature, while others may have a higher temperature and be perfectly well.
What's most important is what's normal for your child. You know your child better than anyone – if you're concerned about their temperature, they probably have a fever.
Find out how to take your child's temperature.
Mild fevers are usually nothing to worry about, and can often be treated at home. They normally pass in a few days.
Read about how to treat a high temperature in children.
Contact your GP, health visitor or NHS 111 if: