The Amazing Guide to Normal Body Temperature: A Must-Read for All Ages

What is the normal body temperature range?

The normal body temperature of humans is 98.6° (Fahrenheit) and 37° (Celsius). Your body temperature may change depending on the time of day or for various other reasons. In general, elderly people’s body temperatures are lower than those of younger people.

Why does body temperature fluctuate?

Body temperature may increase or decrease for a variety of reasons. Some of the vital reasons are:

• Your body temperature typically peaks an hour before going to bed and peaks an hour before waking up.
• Your body temperature will increase when you work out.
• The temperature of women of childbearing age will be lower throughout the first half of their cycle and rise after ovulation.
• Your brain may receive a signal from spicy food that your body is overheating, causing you to perspire unnecessarily.
• Body temperatures in women are often greater than in men.
• Compared to elderly adults, younger people typically have greater body temperatures.
• The average body temperature is higher in heavier people than in lighter people.

Your body temperature changes throughout the day as you move, eat, drink, interact with others and change your surroundings.

Normal temperature in adults

The normal body temperature of an adult is between 97° – 99° Fahrenheit.

Normal temperature in children

Children typically have body temperatures of about 36.4° C. This temperature can vary somewhat from kid to child. In general, a fever of 38° C is considered high. The body naturally raises its temperature to combat diseases like colds and coughs.

Normal temperature in babies

One of the scariest signs for parents can be a fever in their baby, especially if it is high. For infants, the normal temperature is around 36.5° – 37.5° Celsius.

Normal temperature during pregnancy

During pregnancy, the usual body temperature may rise, but there won’t be a significant increase. For instance, if the temperature of pregnant women before pregnancy is 98.2° F, it would be approximately 98.4° F during pregnancy. Most medical professionals think this is typical.

How to take your temperature?

It is always recommended to take your temperature with a digital thermometer. No matter what kind of thermometer you use, follow these safety measures:

• Read the thermometer’s instructions.
• Use warm soapy water to wash your hands before using the thermometer.
• Use rubbing alcohol, soap and warm water to wash the thermometer before and after each use.
• Use a different thermometer for taking rectal and oral temperatures.
• Take your temperature at least 6 hours after taking acetaminophen, ibuprofen or aspirin, which can lower your body temperature.

Ear temperature

The temperature of the ear canal is measured using a digital ear thermometer using an infrared ray. To do this,

• First, turn on the digital thermometer. It should only go as far into your ear canal as specified in the device’s instructions.
• Hold the thermometer firmly in place until you hear it beep to let you know it’s finished.
• Note the temperature after removing the thermometer.

Oral temperature

An oral thermometer is required to measure oral temperature.

• If you’ve recently eaten or drunk, wait for 30 minutes before taking your temperature by mouth.
• Now, turn on the digital thermometer. Put your tongue under the thermometer’s tip.
• Close your mouth around the device for the appropriate period of time or until the thermometer beeps to signify completion.
• Note the temperature after removing the thermometer.

Underarm temperature

A digital thermometer can be placed under your armpit. However, armpit temperatures are usually not as precise as oral temperatures.

• Turn on the digital thermometer. Ensure the thermometer is placed under your armpit, so it contacts skin rather than clothing.
• Hold the thermometer firmly in place until you hear it beep to let you know it’s finished.
• Read the number after removing the thermometer.

Temperature of the temporal arteries

An infrared scanner is used by temporal artery thermometers to gauge the temporal artery’s temperature in your forehead. For this, turn on the digital thermometer and gently glide it across your forehead.

Types of thermometers

There are two types of thermometer, digital thermometers and infrared thermometers. The information on both thermometers is elaborated below.

Digital thermometers

A smart temperature transmitter is checked under flowing conditions and after a successful calibration using a digital thermometer. Thermistors or RTD probes are used with portable electronic thermometers (PETs) to monitor the temperature.

Digital thermometers are temperature-sensing devices with embedded digital displays, permanent probes and easy portability. A digital thermometer’s operation is based on the kind of sensor it uses. Thermocouples, thermistors and resistance temperature detectors (RTD) are examples of sensor types.

Infrared thermometers

An infrared thermometer is a type of thermometer that determines temperature using some of the thermal radiation generated by the object being measured, often known as “black-body radiation”.

Infrared thermometers are mostly used to determine a subject’s temperature from a distance. In such circumstances, the device is helpful where it is challenging to reach the object to record the temperature.

An infrared thermometer is a sensor made out of a lens that directs infrared (IR) energy onto a detector, which then transforms it into an electrical signal that can be displayed in temperature units after being adjusted for variations in the surrounding temperature.

Average temperature by age 

AGE	ARMPIT TEMPERATURE	ORALTEMPERATURE	ARMPITTEMPERATURE
Infants	Celcius – 36.7 – 37.3°C Fahrenheit – 95.8 – 99.3°F	Celcius – 37 – 37.9°C Fahrenheit – 96.8 – 100.3° F	Celcius – 36.4 – 37.3°C Fahrenheit – 94.8 – 98.3°F
Children	Celcius – 36.4 – 37.4° C Fahrenheit – 97.6 – 99.3°F	Celcius – 37 – 37.3°C Fahrenheit – 98.6 – 100.3°F	Celcius – 35.9 – 36.8°C Fahrenheit – 96.6 – 98.3°F
Adults	Celcius – 35.6 – 36.7°C Fahrenheit – 96 – 98°F	Celcius – 36.1 – 37.2°C Fahrenheit – 97 – 99°F	Celcius – 33.3 – 36.4°C Fahrenheit – 92 – 97.6°F
Adults over 65	Celcius – 33.9 – 37°C Fahrenheit – 93 – 98.6°F	Celcius – 34.4 – 37.6°C Fahrenheit – 94 – 99.6°F	Celcius – 33.3 – 36.4°C Fahrenheit – 92 – 97.6°F

Reason for change in body temperature

The following are said to be the main reasons for frequent variations in body temperature.

How active are you?

For your muscles to work, you require energy. Your body temperature rises when you engage in intense physical activity because of the heat that your muscles produce.

Change in time

The average body temperature varies throughout the day in accordance with circadian rhythms peaking in the late afternoon between 4:00 and 6:00 p.m.

The lowest and highest body temperatures of the day are in the morning and the afternoon, respectively. Your body has a sophisticated thermoregulation system that aids in maintaining appropriate temperature ranges.

Body temperature typically rises and falls on a daily cycle as part of the circadian rhythm, reaching its lowest points in the morning and its greatest points in the afternoon and evening.

Age

Our body’s composition, including our body fat percentage, muscular mass, skin and sweat glands changes as we get older. The temperature regulation of our body may be impacted by these changes.

Sex

Over 37° C is the average core body temperature for both men and women. Some research even suggests that the female body temperature is somewhat higher. However, our impression of temperature is more influenced by skin temperature, which is often lower in women.

What you’ve eaten or had to drink

As your metabolic rate rises to allow for food digestion, eating typically causes a minor rise in body temperature. As your body undergoes the chemical reactions required for digestion, your temperature may rise.

These chemical processes are responsible for raising body temperature.

Menstrual cycle

In general, the menstrual cycle may rise during the period. Most people typically have a temperature between 96° – 98° Fahrenheit just before ovulation. It may rise to 97°–99°F after ovulation.

Immediate steps to take when body temperature exceeds the limit

If your body temperature exceeds the normal range (which is typically around 97.5°F to 99.5°F or 36.4°C to 37.5°C), it could be a sign of fever or other medical conditions. Here are some immediate steps you can take:

• Measure your temperature accurately
• Rest and hydrate
• Take medication
• Cool down
• Seek medical attention

Prevention of body temperature

The following are the ways to prevent sudden variations in body temperature.

Wash your hands often

Contaminated hands can transmit a variety of contagious diseases from one person to another.

These illnesses include respiratory infections like the flu, colds and coronavirus (COVID-19) as well as gastrointestinal infections like salmonellosis.

The transmission of the bacteria and viruses that cause these diseases can be halted by thoroughly washing your hands with soap and water, particularly in young infants and the elderly.

Especially before eating

Everyone must check the food before eating it. This prevents food poisoning and other infections from affecting your body.

After using the toilet

Human faeces contain pathogens including E. coli, Shigella, Streptococcus and hepatitis A and E. It is advisable to wash your hands after every bathroom visit.

When to contact a doctor?

If your temperature is 103° F (39.4° C) or above, contact your healthcare professional right away. If any of these warning signs or symptoms appear together with a fever, get help right away from a doctor.

More than three to five days of fever. Fever-relieving drugs like acetaminophen or ibuprofen do not work to reduce fever. Other signs include fuzziness, stiff neck or light sensitivity.

Summing up

You can receive three different readings if you take your temperature using three different types of thermometers. This does not necessarily warrant concern.

So, keep in mind that your typical temperature isn’t always going to be 98.6°F the next time you reach for your thermometer.

Call your primary care physician, however, if you have any queries or worries about your body temperature.

FAQs