A digital thermometer is a modern tool that measures body temperature using electronic sensors. It gives fast and accurate readings on a clear digital screen. Unlike mercury thermometers, it is safe, easy to use, and does not have any harmful substances. It can be placed under the tongue, in the armpit, as per your convenience. This digital thermometer beeps when the reading is ready, making it simple for anyone to use. This thermometer can be used at home, clinics, and hospitals to quickly detect fever. 

1. First, wash your hands and the thermometer tip with lukewarm water. 
2. Turn on the thermometer by pressing the power button. You will see the display light up. 
3. Choose where you want to measure the temperature. Most commonly, people place the thermometer under the armpit for 60 seconds or under the tongue for 30 seconds. 
4. For under the armpit, hold the thermometer firmly in place against the skin. Keep your arm close to your body. 
5. For under the tongue, place the thermometer tip gently under the tongue, towards the back of the mouth. Keep your mouth closed. 
6. Wait patiently until you hear a beeping sound. This means the temperature reading is complete. 
7. Remove the thermometer and read the temperature shown on the digital screen. 
8. Clean the thermometer tip with lukewarm water and dry it completely. 
9. Store the thermometer in its protective case in a cool, dry place.

A digital thermometer contains a tiny sensor called a thermistor inside its tip. When the thermistor meets your skin or mouth, it senses the heat from your body. This heat causes the thermistor to change its electrical charge in it. The thermometer’s internal computer reads this change and converts it into a temperature reading. The reading is then displayed on the digital screen in degrees Celsius or Fahrenheit.

What is considered a normal body temperature? 

Normal body temperature for an adult is around 37°C (98.6°F). However, normal temperature can range from 36.1°C to 37.2°C depending on the individual. Body temperature tends to be lower in the morning and higher in the evening. Children may have slightly higher normal temperatures compared to adults.

What does a fever temperature mean?

A fever occurs when your body temperature is above 38°C (100.4°F). A fever is usually a sign that your body is fighting an infection like cold, flu, or other illness. However, not all fevers require immediate medical attention. If the fever lasts more than 3 days, is very high, or is accompanied by severe symptoms, consult a doctor.

Is it better to take temperature under the arm or under the tongue?

Both methods are accurate with a digital thermometer, but they give slightly different readings. Under the tongue (oral) readings are usually 0.5°C higher than under the arm (axillary) readings. For consistency, use the same method each time. Under the arm is safer and more comfortable for young children and infants. Under the tongue is faster and commonly used for older children and adults.

How often should I replace my thermometer?

A well-maintained digital thermometer can last many years. Replace it if the battery is dead, the display no longer works, the tip is cracked or damaged, or if it gives inconsistent readings. Most digital thermometers last 3 to 5 years with proper care.

Can I use a digital thermometer on a newborn or infant?

Yes, digital thermometers are safe for newborns and infants. For babies under 3 months, it is best to take the temperature under the arm and keep them still during measurement. Do not use the oral method for infants. Always consult your pediatrician if your baby has a fever, as this can indicate a serious infection in young children.

Why does my thermometer show different readings?

Small variations in temperature readings are normal and can happen due to several reasons. These include measuring at different body locations, moving during measurement, not waiting long enough, or using different thermometers. For accurate readings, use the same method and location each time, wait for the beep, and keep the thermometer still. If readings differ by more than 1°C from your usual temperature, the thermometer may need replacement.

1. Encyclopaedia Britannica. Thermometer | Definition, Types, & Facts. [Internet]. Encyclopaedia Britannica; 2026 Apr 24 [cited 2026 Jun 24]. Available from. 
2. Mayo Clinic Staff. Thermometers: Understand the options [Internet]. Rochester (MN): Mayo Foundation for Medical Education and Research; 2026 Jan 20 [cited 2026 Jun 24]. Available from. 
3. The Physics Classroom. Thermal Physics – Heat and Temperature: Temperature and Thermometers [Internet]. The Physics Classroom; 2026 [cited 2026 Jun 24]. Available from.