**A fever is a body temperature of 100.4°F (38°C) or higher.**
Normal is a range, not one number: most healthy adults sit between about 97°F and 99°F, and your reading is lowest in the morning and highest in the late afternoon. Where you measure changes the result, so rectal and ear readings tend to run higher than oral, while armpit and forehead readings tend to run lower. Readings between 99°F and 100.3°F are usually called a low-grade or elevated temperature rather than a fever. In adults, how sick you feel and what other symptoms you have matter more than the exact number on the thermometer. Take your temperature before eating, drinking, or exercising, and write down the number, the time, and the method you used so you can track the pattern.
When a fever needs a doctor
Common questions
“what temperature is a fever?”
A fever is a body temperature of 100.4°F (38°C) or higher. Normal is a range: most people sit between about 97°F and 99°F, and your temperature runs lower in the morning and higher in the late afternoon. The site matters, so rectal and ear readings run a bit higher than oral, and armpit and forehead readings run a bit lower. Note which method you used. In adults, your other symptoms matter more than the exact number. Get medical care for a fever above 103°F, a fever lasting more than 3 days, or a fever that keeps returning. Any fever of 100.4°F or higher in a baby under 3 months needs same-day medical care.