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Body Temperature Calculator

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Enter your body temperature reading to check which category it falls into.

Body Temperature Calculator

Live
Category
Normal
Converted
37.0 C
Based on oral temperature readings. Rectal and ear readings run slightly higher; armpit readings run slightly lower. This is informational only, not a diagnosis.

The classification (oral temperature)

Low (Hypothermia): under 95.0 F (35.0 C) Normal: 95.0-99.0 F (35.0-37.2 C) Low-grade fever: 99.1-100.3 F (37.3-37.9 C) Fever: 100.4-102.9 F (38.0-39.4 C) High fever - seek care: 103.0-104.9 F (39.4-40.5 C) Emergency - seek immediate care: 105.0 F+ (40.6 C+)
Example

98.6 F (37.0 C), the classic "normal" reference point, falls squarely in the Normal range.

Step-by-step guide

  1. Wait at least 20-30 minutes after eating, drinking, or exercising before taking an oral reading - these can temporarily skew the number.
  2. Enter your reading and select the correct unit (Fahrenheit or Celsius) - the calculator converts and classifies automatically.
  3. Read your category. If it's a fever, consider rechecking in 30-60 minutes to see whether it's rising, stable, or coming down.

How measurement site changes the reading

This calculator uses oral reference ranges, the most common home measurement method. But where you measure genuinely changes the number: rectal and ear (tympanic) readings tend to run about 0.5-1 F higher than oral, since they're closer to core body temperature, while armpit (axillary) readings tend to run about 0.5-1 F lower, since skin temperature is naturally cooler than internal temperature. Comparing a rectal reading against oral thresholds - or vice versa - can make a normal reading look like a fever, or a real fever look deceptively mild.

Common mistakes

Comparing a rectal or ear reading directly against oral thresholds - each measurement site has a slightly different normal baseline, so mixing them up can lead to misreading a normal temperature as feverish, or the reverse.
Taking a reading right after a hot drink, a hot bath, or vigorous exercise - all of these temporarily raise the number regardless of your actual baseline temperature.

Frequently asked questions

Is 98.6 F really "normal" for everyone?

It's the classic reference point, but individual normal temperature varies by about 1 F between people, and fluctuates through the day - typically lowest in early morning and highest in late afternoon. Some more recent research suggests the modern average may run slightly cooler, around 97.9 F.

Does the measurement method (oral, ear, forehead) matter?

Yes - this calculator uses oral reference ranges. Rectal and ear (tympanic) readings tend to run slightly higher than oral, while armpit (axillary) readings tend to run slightly lower.

When should I seek medical care for a fever?

Generally at 103 F (39.4 C) or higher for adults, or any fever accompanied by severe symptoms like confusion, difficulty breathing, or a stiff neck. Thresholds are much lower for infants - any fever in a baby under 3 months warrants immediate medical attention.

Why does my temperature seem to change throughout the day?

Body temperature naturally follows a daily rhythm, running roughly 0.5-1 F lower in early morning and higher in late afternoon or evening - a completely normal pattern, not a sign of illness on its own.

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