Normal Human Body Temperature: 37°C and 98.6°F Explained | Class 6
What Is the Normal Human Body Temperature?
Most asked question in this chapter — write this exactly
The normal temperature of the human body is 37°C or 98.6°F.
This is one of the most frequently tested facts in Class 6 Science exams — it appears as a fill-in-the-blank, a one-mark question, or as part of a longer answer about thermometers. Write both values: 37°C and 98.6°F.
37°C and 98.6°F — Understanding Both Values
The same temperature is written differently on the two scales:
🌡️
Celsius scale
37°C
used in India & science
🌡️
Fahrenheit scale
98.6°F
marked on clinical thermometers
Both values mean the same temperature — just expressed in different units. In India and in CBSE exams, 37°C is the primary value to remember. But 98.6°F is also tested, especially as a fill-in-the-blank.
💡 Memory tip: 37°C · 98.6°F · Normal body. Write this line three times and you'll never forget it.
What Is Fever?
Fever is when the body temperature rises above its normal value of 37°C. A temperature of 38°C or above is generally considered a fever and may indicate that the body is fighting an infection.
Temperature (°C)
What It Means
35°C–36.5°C
Below normal (possible hypothermia if very low)
36.5°C–37.5°C
Normal range
37.5°C–38°C
Slightly elevated — possible early fever
38°C–40°C
Fever — medical attention may be needed
Above 40°C
High fever — seek immediate medical attention
✅ Exam-ready answer
When does a person have a fever?
Show Answer
A person is said to have a fever when their body temperature rises above the normal value of 37°C (98.6°F). A temperature of 38°C or above usually indicates fever.
Why Does the Body Maintain a Constant Temperature?
The human body is designed to keep its temperature close to 37°C at all times. This is because most of the chemical processes inside the body — especially those involving enzymes — work best at this temperature.
When you are ill, your body may raise its temperature deliberately as part of fighting infection. This is what we call fever — it is the body's own defence response, not just a symptom.
💡 This concept — that the body maintains a constant internal temperature — is called thermoregulation. You don't need to use this word in Class 6, but understanding the idea helps you answer "why" questions.
Why Is the Clinical Thermometer Range 35°C to 42°C?
A clinical thermometer has a range of 35°C to 42°C. This range is deliberately chosen because:
35°C is the lower boundary — a human body temperature below this would indicate a serious medical emergency (hypothermia)
42°C is the upper boundary — a human body temperature above this is extremely dangerous and requires immediate emergency care
The range is narrow and precise — which is exactly what is needed for detecting small temperature differences that indicate illness. This is why a laboratory thermometer (range −10°C to 110°C) is not suitable for this purpose.
✅ Exam-ready answer
Why is the range of a clinical thermometer 35°C to 42°C?
Show Answer
The range of a clinical thermometer is 35°C to 42°C because this covers the complete range of possible human body temperatures — from dangerously low (35°C) to dangerously high fever (42°C). A normal body temperature of 37°C falls well within this range.
How Body Temperature Is Measured
Body temperature is measured using a clinical thermometer. Here is the correct procedure:
Wash the thermometer with cold water and antiseptic solution.
Jerk the thermometer downward several times to bring mercury below 35°C.
Place the bulb of the thermometer under the tongue and keep the mouth closed. (It can also be placed in the armpit.)
Wait for 1–2 minutes without removing the thermometer.
Remove and hold horizontally at eye level to read the mercury level.
Record the reading. Wash the thermometer again before storing.
⚠️ Common mistake
Never use a laboratory thermometer to measure body temperature.
A laboratory thermometer has no kink — the mercury falls back the moment you remove it from the mouth. You cannot get an accurate reading. Only use a clinical thermometer for body temperature.
Other Reference Temperatures to Know
Key temperatures — CBSE Class 6
Water freezes
0°C (32°F)
Normal human body temperature
37°C (98.6°F)
Fever threshold
38°C+ (100.4°F+)
Water boils
100°C (212°F)
Exam-Ready Answers
✏️ Fill in the blank
The normal temperature of the human body is .
✍️ 2-mark answer
What is the normal temperature of the human body? What does it mean if the temperature is above this?
Correct Answer: The normal temperature of the human body is 37°C or 98.6°F. If the body temperature rises above 37°C — typically to 38°C or higher — it is called fever. Fever usually indicates that the body is fighting an infection or illness.
✍️ 1-mark answer
What is the upper limit of a clinical thermometer and why?
Correct Answer: The upper limit of a clinical thermometer is 42°C. This is because a human body temperature above 42°C is extremely dangerous and would require emergency medical care — so no higher range is needed.
🎯 Multiple Choice
Which thermometer should NEVER be used to measure human body temperature?
Frequently Asked Questions
What is the normal temperature of the human body?
The normal temperature of the human body is 37°C or 98.6°F.
What temperature is considered fever?
A temperature above 37°C is generally considered elevated. A reading of 38°C or above is typically considered a fever and may indicate that the body is fighting an infection.
Which thermometer is used to measure body temperature?
A clinical thermometer is used to measure body temperature. Its range is 35°C to 42°C, which covers all possible human body temperatures from dangerously low to dangerously high.
Why is the range of a clinical thermometer 35°C to 42°C?
This range is chosen because it covers the complete spectrum of human body temperatures. 35°C marks dangerously low body temperature (hypothermia), and 42°C marks dangerously high fever. Normal body temperature (37°C) falls comfortably in the middle.
Why does the body maintain a constant temperature?
The body maintains a constant temperature of around 37°C because this is the optimum temperature for the body's biological and chemical processes to function correctly. When you are ill, this temperature may rise (fever) as the body responds to infection.
Is 37°C and 98.6°F the same temperature?
Yes. 37°C and 98.6°F are the same temperature — just expressed in different units. Celsius and Fahrenheit are two different scales for measuring temperature. In India, Celsius is the standard scale used.