What is a normal temperature?
Last updated September 3, 2026.
Normal is a range: 97.7F to 99.1F (36.5C to 37.3C), averaging 98.6F, per MedlinePlus - and it moves: cooler in early morning, warmer by evening, up after exercise, and different by measurement site. Fever starts at 100.4F (38C), and most fevers pass in two to three days. The action thresholds: call a doctor at 103F (39.4C) holding or climbing, any fever past 48-72 hours, or fevers recurring a week-plus; confusion, stiff neck, breathing trouble, or seizure with fever is an emergency; a baby under 3 months at 100.4F is always same-day. Below 95F (35C) is hypothermia territory, also an emergency. Track with the same method each time - cross-thermometer comparisons mislead. Pymander is a free AI doctor, 24/7 by text, and can read a temperature in context.
What to do
- Compare like with like: same thermometer, same site.
- 100.4F is the fever line: most pass in 2-3 days.
- 103F, 3 days, or warning signs? Call.
- Baby under 3 months at 100.4F? Same-day care, always.
Related questions
- Should I see a doctor for a fever?
- What is a normal heart rate?
- What is a normal oxygen level?
- When should I worry about my numbers?