Body Temperature Converter
About body temperature
Body temperature is commonly measured in Celsius (°C), Fahrenheit (°F), or Kelvin (K). This converter helps you switch between scales quickly and consistently.
Reminder: Kelvin is an absolute scale (0 K is absolute zero).
How the converter works
- Choose your input unit (°C, °F, or K).
- Enter a single temperature value.
- Press Calculate to see all three units.
- Use Copy or Share to save your result.
Units & scales
- Celsius (°C): water freezes at 0 °C and boils at 100 °C at sea level.
- Fahrenheit (°F): water freezes at 32 °F and boils at 212 °F.
- Kelvin (K): 0 K = absolute zero; size of 1 K equals 1 °C.
Tip: Medical thermometers typically read in °C or °F. Kelvin is mainly scientific.
Conversion formulas
Between °C and °F
°F = (°C × 9/5) + 32
°C = (°F − 32) × 5/9
Involving Kelvin
K = °C + 273.15
°C = K − 273.15
The converter applies these formulas precisely, then rounds the display for readability.
Typical body temperature ranges (adults)
Exact “normal” varies by person, time of day, and measurement site. These are common reference ranges:
Rectal readings are typically higher; axillary (underarm) typically lower than oral.
Helpful tips
- Use the same measurement site (oral, tympanic, rectal, axillary) for consistent tracking.
- Avoid hot/cold drinks 15 minutes before an oral reading.
- Take multiple readings if a result seems unusual, then average.
Common mistakes
- Mixing units (reading in °F but entering as °C, or vice versa).
- Comparing a rectal reading against oral reference ranges.
- Not waiting long enough for a digital thermometer to stabilize.
Frequently asked questions
Why does my temperature change during the day?
Body temperature follows a daily rhythm—lower in the morning, higher in late afternoon/evening.
Is a “normal” temperature the same for everyone?
No. Genetics, age, sex, activity, and measurement site affect what’s “usual” for an individual.
When should I seek medical advice?
Seek professional guidance for persistent fever, very high readings, concerning symptoms, or if you’re caring for infants, older adults, or immunocompromised individuals.
Important note
This content is informational and not a substitute for professional medical advice. Always follow your healthcare provider’s instructions.