Temperature Converter - Celsius to Fahrenheit

Temperature Conversion Formulas

Convert	Formula	Example
°C → °F	°F = (°C × 9/5) + 32	37°C = (37 × 1.8) + 32 = 98.6°F
°F → °C	°C = (°F − 32) × 5/9	98.6°F = (98.6 − 32) × 0.5556 = 37°C
°C → K	K = °C + 273.15	37°C = 310.15 K
K → °C	°C = K − 273.15	310.15 K = 37°C
°F → K	K = (°F + 459.67) × 5/9	98.6°F = 310.15 K

Clinical Temperature Thresholds

Fever is defined as a core body temperature ≥38.0°C (100.4°F) by the CDC and most international guidelines. In clinical practice, the measurement site affects readings: rectal temperature runs ~0.5°C higher than oral, which runs ~0.5°C higher than axillary. Tympanic temperatures are convenient but less accurate. Normal body temperature varies between individuals and throughout the day (lowest in early morning, highest in late afternoon).

Fever in Children

Fever thresholds and urgency differ by age: any rectal temperature ≥38.0°C in an infant under 3 months warrants prompt medical evaluation, regardless of how well the baby otherwise looks. For weight-based antipyretic dosing (paracetamol/acetaminophen or ibuprofen) once a child is old enough for home management, see our Pediatric Dose Calculator.

Hypothermia

Hypothermia is a core temperature below 35.0°C (95.0°F), and the CDC notes that shivering, exhaustion, confusion, fumbling hands, memory loss, and slurred speech are the warning signs to watch for. It is a medical emergency at any temperature below this threshold and can occur even in mild weather if someone is wet, exhausted, or elderly.

Fever and Pneumonia Severity

Fever is one of the classic presenting symptoms of community-acquired pneumonia, though it is not itself a scored criterion in most severity tools. If pneumonia is suspected alongside a fever, our CURB-65 Score assesses severity and helps guide the admission decision.

Note: The long-held "37°C = 98.6°F" as a universal normal has been challenged by recent research showing mean oral temperature in adults is closer to 36.6°C (97.9°F) and declines slightly with age.

Frequently Asked Questions

Why is normal body temperature not always 37°C (98.6°F)?+

37°C (98.6°F) is the classic figure from an 1851 German study, still widely taught and used as a reference point. More recent, larger studies put the average closer to 36.6°C (97.9°F), and normal temperature varies meaningfully between individuals, by time of day (lowest in early morning, highest in late afternoon), by measurement site, and by age. A single reading a little below 37°C is not necessarily abnormal.

What temperature counts as a fever in a baby versus an adult?+

The numeric threshold, a core temperature of 38.0°C (100.4°F) or above, is the same across ages, but the urgency differs sharply. In an infant under 3 months, this reading warrants prompt medical evaluation regardless of how well the baby otherwise looks, because young infants can deteriorate quickly and cannot reliably signal how unwell they are. In older children and adults, the same reading is usually managed at home unless accompanied by other concerning symptoms.

Does it matter if I round a converted clinical temperature?+

For most clinical purposes, one decimal place in Celsius or Fahrenheit is sufficient precision, temperature thresholds like the 38.0°C fever cut-off already carry some built-in tolerance for measurement variation between devices and sites. Where rounding matters more is right at a threshold: a reading of 37.95°C rounds to 38.0°C and crosses into the fever range, so it is worth using the precise figure rather than a heavily rounded one when a decision hinges on being just above or below a cut-off.