One medical gadget that holds an important place in assessing the health condition of all people, particularly in these times of COVID-19 pandemic is none other than a thermometer. Fever being the most common symptom of coronavirus, thermometer can help a person precisely indicate if the body temperature is higher or lower than normal, thereby assisting to take a prompt course of treatment and ensuring a faster recovery.

Well, having a reliable medical thermometer at home can be greatly valuable. The ability to find out if someone has a fever offers basic information about further vital actions to be taken care of. The average normal temperature of the human body is between 97 to 98.6 °F or 36.1 to 37.5°C, and temperature above 100.4°F (38°C) means that a person has a fever which is caused by an infection or illness.
A Hand Holding A Digital Thermometer

There are several types of contact and contact-free thermometers are available to choose from. This depends on the age of family members, as well as a personal choice, which helps a person to finalize which type to buy.

However, it’s also essential to understand how different types of thermometers work, before using it, as not all types work the same way or are designed to provide the same readings.

Also Read: Fever: Types, Causes, Symptoms And Treatment

Types of thermometers

Generally, there are two types of thermometers - touch and contact. Thermometers must touch the body to measure the temperature, while remote or no contact thermometers can measure body temperature without touching the skin.

Contact Thermometers

Contact thermometers are common type of thermometer, which uses electronic heat sensors to record body temperature. It can be placed on the forehead, mouth, armpit, or rectum. Most electronic thermometers have a digital display that indicates the temperature reading.

Rectal temperatures offer the most precise reading for infants,3 months or younger, as well as children 3 years of age. Temperature monitored from the armpit is least accurate. For older children and adults, oral readings are precise, if the mouth remains closed while the thermometer is in place.

Remote Thermometers

Many schools, business organizations and health care setups are regularly monitoring the visitors for fever. A remote thermometer is beneficial, as it doesn’t require any skin contact and allows people to stay further apart. Remote thermometers can be used on the forehead or the ear.

Digital Thermometers

This type of thermometer works by using heat sensors that determine body temperature. It can be used to take temperature readings in the mouth, rectum, or armpit. When measuring temperature using a digital thermometer, keep a note that armpit (axillary) temperature runs about ½ to 1°F (0.6°C) lower than oral readings. Rectal thermometers run ½ to 1°F (0.6°C) higher than oral readings.
Different types of thermometers


  • Digital thermometers offer accurate readings in about 1 minute or less


  • To get a precise reading from oral use, the tip of the device should be kept under the tongue with the mouth fully closed. For this reason, rectal readings are thought to be more accurate
  • Oral readings won’t be correct if they are checked too close when a person had any hot food or drink, as the results may be altered by the food or drink’s temperature
  • Rectal reading may be difficult to take for infants and small children
  • Remember not to use the same digital thermometer for both rectal and oral readings. You may have to purchase two thermometers and labelled them separately
  • Ensure to replace batteries periodically. Get the right type of batteries on hand for the device and get to know how to change them

Digital Ear (Tympanic) Thermometer

This type of thermometer measures the temperature inside the ear canal via infrared ray technology. The readings are 0.5°F (0.3°C) to 1°F (0.6°C) higher than oral temperature readings.


  • Tympanic thermometers offer fast and accurate readings, and it is preferable to assess both oral and rectal thermometers, especially in children


  • Tympanic thermometers are not ideally suggested for infants less than 6 months old
  • It must be placed properly to get precise results
  • Obstructions like earwax may alter the results
  • They may not suit small or curved ear canal

Forehead (Temporal) Thermometer

This type of thermometer uses infrared sensors to check the temperature of the superficial temporal artery. They are known as non-contact infrared thermometers. Forehead thermometers basically require no physical contact, thus have become very famous for use in public places like airports, stations, stores, and stadiums etc. The temperature readings run around 1°F (0.6°C) lesser than oral temperature readings.


  • Temporal thermometers offer quick results, within few seconds
  • They are easy to use, and it is highly reliable for infants, children, and adults


  • Forehead thermometers should be placed accurately as per the manufacturer’s instructions or else they will not give the right value
  • Readings can be affected by certain external factors like wind, indoor heating, and sunlight
  • Clothing such as hats or heavy coats can also alter the results

How To Measure An Oral Temperature?

To take temperature reading orally with a digital thermometer:

Wash your hands thoroughly.

Clean the thermometer and check if batteries are working.

Turn on the thermometer, slide the plastic sheath over the bottom tip of the thermometer.

The thermometer will indicate that it’s ready for use popping with a sound and light.

Place the thermometer’s tip beneath the tongue and keep your mouth closed until you hear a beep type of sound.

Take the thermometer and read the value.

Wash your hands again and clean the thermometer after using it, as per the instructions given by the manufacturer.

How To Take A Rectal Temperature?

To take the temperature rectally with a digital thermometer:

Clean your hands well.

Ensure your thermometer is clean and has good working batteries.

Cover the tip of the thermometer with a plastic heath and apply a lubricant like petroleum jelly.

Babies should be placed on their backs with legs in the air, while children and adults may find it comfortable lying on their stomach.

Turn the thermometer on and gently insert the tip of the thermometer into the rectum, not more than 1 inch.

Hold it in place and wait for the beep sound.

Remove the thermometer and read the value.

Clean the thermometer well as per the manufacturer’s instructions before storing and reusing.

Rewash your hands.

How To Take The Temporal Temperature With A No-Touch Forehead Thermometer?

No-touched forehead thermometers have a removable cap, which keeps them clean during storage.

Switch the power button, when the thermometer is ready, place it not more than 2 inches away from the centre of the forehead.

Hold the thermometer steady. The thermometer and forehead should be free of any movement to get a precise reading.

Press the temperature button, the device will beep and let you know once the temperature is ready to be read and it will take only 2 seconds.

Instructions may vary by manufacturer, so ensure to read and follow the directions given in the user’s manual that come with the device.