Body Temperature Chart – Normal, Fever & Hypothermia Ranges (°C & °F)
Last updated: February 28, 2026
A complete reference guide to human body temperature ranges across age groups. All values are shown in both Celsius (°C) and Fahrenheit (°F).
Normal Body Temperature
The widely cited "normal" body temperature of 37 °C (98.6 °F) comes from a study by German physician Carl Reinhold August Wunderlich in 1851, based on over one million readings from 25,000 patients. More recent research suggests the average has shifted slightly downward, with a 2017 analysis of about 35,000 British patients finding a mean oral temperature of 36.6 °C (97.9 °F) (Obermeyer et al., BMJ), and a 2020 Stanford University study (Protsiv et al., eLife) documenting a decline of about 0.03 °C per birth decade in the United States.
Normal body temperature is not a single fixed number. It fluctuates throughout the day — typically lowest in the early morning and highest in the late afternoon — and varies by measurement site, age, sex and physical activity.
Body Temperature Ranges by Category
| Category | Celsius | Fahrenheit |
|---|---|---|
| Severe hypothermia | < 28 °C | < 82.4 °F |
| Moderate hypothermia | 28–32 °C | 82.4–89.6 °F |
| Mild hypothermia | 32–35 °C | 89.6–95 °F |
| Below normal | 35–36.1 °C | 95–97 °F |
| Normal range | 36.1–37.2 °C | 97–99 °F |
| Slightly elevated (not a fever) | 37.3–37.9 °C | 99.1–100.3 °F |
| Fever | 38.0–39.4 °C | 100.4–103 °F |
| High fever | 39.5–41 °C | 103.1–105.8 °F |
| Hyperpyrexia (emergency) | > 41 °C | > 105.8 °F |
Normal Ranges by Age Group
| Age Group | Normal Range (°C) | Normal Range (°F) |
|---|---|---|
| Newborns (0–3 months) | 36.5–37.5 °C | 97.7–99.5 °F |
| Infants (3–12 months) | 36.0–37.4 °C | 96.8–99.3 °F |
| Children (1–10 years) | 36.1–37.8 °C | 97.0–100.0 °F |
| Adults (11–65 years) | 36.1–37.2 °C | 97.0–99.0 °F |
| Older adults (> 65 years) | 35.8–36.9 °C | 96.4–98.4 °F |
Temperature by Measurement Method
Where you measure body temperature affects the reading. Rectal and ear (tympanic) measurements tend to read higher than oral, while axillary (armpit) readings tend to be lower.
| Method | Normal Average (°C) | Normal Average (°F) |
|---|---|---|
| Oral (mouth) | 36.8 °C | 98.2 °F |
| Rectal | 37.0 °C | 98.6 °F |
| Axillary (armpit) | 36.5 °C | 97.7 °F |
| Tympanic (ear) | 36.9 °C | 98.4 °F |
| Temporal (forehead) | 36.6 °C | 97.9 °F |
Fever Thresholds in Children
Pediatric fever thresholds differ from adults. The American Academy of Pediatrics uses the following fever thresholds in children, depending on the measurement method. The WHO (IMCI guidelines, children aged 2 months to 5 years) uses an axillary temperature of 37.5 °C (99.5 °F) or higher, equivalent to 38 °C (100.4 °F) rectally.
| Method | Fever Threshold (°C) | Fever Threshold (°F) |
|---|---|---|
| Rectal | 38.0 °C | 100.4 °F |
| Oral | 37.8 °C | 100.0 °F |
| Axillary | 37.2 °C | 99.0 °F |
| Tympanic | 38.0 °C | 100.4 °F |
For infants under 3 months, a rectal temperature of 38 °C (100.4 °F) or higher always requires prompt medical evaluation, regardless of other symptoms.
Factors That Affect Body Temperature
- Time of day: Temperature is lowest between 4:00–6:00 AM and peaks between 4:00–6:00 PM, with a typical variation of 0.5–1.0 °C (0.9–1.8 °F).
- Physical activity: Exercise can raise body temperature by 1–2 °C (1.8–3.6 °F) temporarily.
- Menstrual cycle: Women's basal body temperature rises by about 0.3–0.5 °C (0.5–0.9 °F) after ovulation due to progesterone.
- Age: Older adults have lower baseline temperatures and may not develop high fevers as readily.
- Ambient temperature: Extreme heat or cold can influence peripheral and core body temperature.
- Food and drink: Consuming hot or cold beverages before an oral reading can temporarily alter results.
When to Seek Medical Attention
- Adults: Fever above 39.4 °C (103 °F) or lasting more than 3 days
- Children: Fever above 40 °C (104 °F), lasting more than 5 days, or with unusual behavior or breathing problems (Cleveland Clinic)
- Infants under 3 months: Any fever at or above 38 °C (100.4 °F)
- Any age: Temperature above 41 °C (105.8 °F) — this is a medical emergency
- Hypothermia: Temperature below 35 °C (95 °F) — seek immediate medical help
Frequently Asked Questions
What is normal body temperature in Celsius and Fahrenheit?
The traditional reference is 37 °C (98.6 °F); modern measurements put the average oral temperature closer to 36.6 °C (97.9 °F). Normal ranges can vary between 36.1 °C (97.0 °F) and 37.2 °C (99.0 °F) depending on time of day, activity level and measurement method.
At what temperature is a fever considered dangerous?
In adults, a fever above 39.4 °C (103 °F) warrants a call to a healthcare provider (Cleveland Clinic). A fever itself starts at 38 °C (100.4 °F) (CDC). For infants under 3 months, any fever at or above 38 °C (100.4 °F) requires immediate medical evaluation.
What is hypothermia temperature?
Hypothermia occurs when body temperature drops below 35 °C (95 °F). Moderate hypothermia is 28–32 °C (82.4–89.6 °F) and severe hypothermia is below 28 °C (82.4 °F), which can be life-threatening.
Does body temperature change with age?
Yes. Infants and young children tend to have slightly higher baseline temperatures (up to 37.5 °C / 99.5 °F) due to faster metabolism. Older adults often have lower baseline temperatures (around 36.2 °C / 97.2 °F), which can make fever detection more difficult.
Related Temperature Conversions
Data Accuracy
Temperature ranges on this page are based on published clinical guidelines from the American Academy of Pediatrics, NHS, and peer-reviewed medical literature. All Celsius-to-Fahrenheit conversions use the standard formula °F = °C × 9/5 + 32, consistent with the International Temperature Scale of 1990 (ITS-90).
About This Page
Content maintained by the CelsiusFahrenheit.co editorial team. All conversions follow the International Temperature Scale of 1990 (ITS-90) as defined by the Bureau International des Poids et Mesures (BIPM). Calculations use IEEE 754 double-precision arithmetic. Last reviewed: February 2026.