🌡️ Temperature Converter
Type in any field — the other two update instantly.
| Category | Celsius | Fahrenheit | Guidance |
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Frequently Asked Questions
How do I use the Temperature Converter?
Type a value into any of the Celsius, Fahrenheit, or Kelvin fields — the other two fields update instantly. Below, select an age group (Adult, Teen, Child, Toddler, Infant, or Newborn) to see the relevant fever reference table and guidance for the entered temperature.
How do I convert Celsius to Fahrenheit?
°F = (°C × 9/5) + 32. For example, 37°C converts to 98.6°F. To go the other way, °C = (°F − 32) × 5/9.
How do I convert to Kelvin?
K = °C + 273.15. Kelvin has no negative values — 0 K (absolute zero) equals −273.15°C. There is no degree symbol used with Kelvin.
What is considered a fever?
A body temperature above the normal range for the selected age group (typically above 37.5–38°C / 99.5–100.4°F for adults) is generally considered a fever, though exact thresholds vary by measurement method (oral, axillary, rectal, tympanic) and the guideline followed.
Why does the fever reference change by age group?
Normal body temperature and fever thresholds vary across newborns, infants, toddlers, children, teens and adults, based on guidelines from WHO, IAP, API, AAP and NICE. Selecting the correct age group gives a more relevant reference range and guidance.
How do I track a child's exact age for fever monitoring?
Use our Age Calculator to find a child's exact age in years, months and days, which helps pick the right age group for temperature guidance.
Why is -40° the same in both Celsius and Fahrenheit?
-40°C and -40°F represent the same temperature because that's the point where the two linear scales (°F = °C × 9/5 + 32) intersect. Solving °C = °C × 9/5 + 32 gives °C = -40, so it's the only value where both scales agree.
Why do oral, axillary, and rectal thermometers give different readings?
Rectal readings run about 0.5–1°C higher than oral readings, while axillary (armpit) readings run about 0.5°C lower than oral. This calculator's fever thresholds are general guidance — always note which measurement method was used when comparing against a reference range.