What Is A Digital Thermometer?

What Is A Digital Thermometer?

Last Updated on by Daniel Lawrence

You don’t have to be a medical person to own a digital thermometer. In fact, every home is expected to own a digital thermometer. In this guide, we’ll tell you all you need to know about digital thermometers.

What Is A Digital Thermometer?

A digital thermometer is a device that you use to check the temperature of the body. When your baby is showing signs of a fever, the first thing that you will resort to is a thermometer to check your baby’s temperature.

Digital thermometers are used in industry and the home, in applications including food preparation, manufacturing, medical and scientific testing, and procedures.

However, taking a baby’s temperature can be confusing to first-time parents. Having a good understanding of the different types of thermometers will help you to make the right choice.

How Digital Thermometers Work

Digital thermometers contain a small computing mechanism and a resistor. A change in temperature causes the sensor to notice a change in resistance. The computer converts the difference in resistance into a difference in temperature and offers a digital readout in degrees. The thermoresistor sensor is called a thermistor.

High-quality digital thermometers like the MOBI Flex Temp Flexible Tip Thermometer are available for a relatively low cost because good thermistors are available at a low cost. When a quality sensor is combined with other quality parts and well-designed housing, the result is a useful and accurate instrument that can serve the whole family for years.

Thermistors are used in a variety of electronic devices where temperature changes must be taken into account. They can take the place of circuit breakers or fuses to shut down temperature-sensitive electronics to prevent overheating damage. They can also be used in heating and air conditioning thermostats. In that case, they replace bimetallic strips or mercury sensors, which are more likely to fail.

Other Kinds Of Thermometers

Digital thermometers and the thermistors on which they’re based are safer, faster, and easier to read than old-fashioned mercury thermometers. Mercury inside a glass tube is perhaps the simplest kind of thermometer. As the mercury gets hotter, it expands by an amount that relates directly to the temperature increase.

While not often used in medical thermometers, there are also dial thermometers that work by showing how much a metal coil expands with heat. The higher the temperature, the more the internal bimetallic strips expand and the higher the hands on the dial read.

Electronic thermometers and the thermistors inside them have an important advantage over mercury and mechanical thermometers. Thermistors react to temperature changes almost immediately. Mercury and metallic strips take some time to react, meaning that getting an accurate reading takes from a minute to several minutes.

Plus, the computer inside an electronic thermometer can display results in Fahrenheit, Celsius, or any other units for which it’s programmed. The only downside is that the results can vary from moment to moment while mechanical and mercury thermometers are slow to move and therefore don’t have time to respond to minor fluctuations.

Let us look into some of the advantages of a digital thermometer.

Actual temperature 

A digital thermometer can measure the actual body temperature. It does not just measure the surface temperature like other conventional thermometers. You do not need the surface temperature to diagnose the fever. Also because the temperature in the armpits and mouth, where the traditional thermometers are placed gives out fluctuating readings. A digital thermometer can be placed in the ear and it uses special infrared laser methodology to record the internal temperature of the body very accurately.


A digital thermometer will give you the readings in a matter of few seconds. The old thermometers took time to give the temperature readings. It would take more than one minute to show the temperature. But, digital thermometers do not need any recalibrating or shaking and show the reading in the blink of an eye.


A digital thermometer can store almost ten of the previous readings. This will help you in comparing the improvements during a fever.


The digital thermometers are sleek and very handy. All you need to do is press a button lightly and you get the temperature readings. The mercury thermometer had to be shaken vigorously to make it work efficiently. It is also not prone to breakage like glass thermometers.


For all those people who do not understand the different scales of temperature, a digital thermometer is a boon. It shows the temperature in both degrees Celsius and Fahrenheit.

Disadvantages Of Digital Thermometers

At first glance, a digital thermometer seems to be the best choice for measuring temperatures. When choosing digital, you avoid the mercury risk of other thermometer types. Another advantage is the easy-to-read digital display. However, while there are benefits, there are also disadvantages to digital thermometers.

  • Battery Issues

Dead batteries are a drawback of digital thermometers. It is hard to determine how much power is left in a digital thermometer’s battery, which in turn makes it difficult to predict when it will die. Because they are specialized batteries, it is hard to locate replacements. And close-to-dying batteries will provide inaccurate readings. Replace your battery annually to prevent power-related problems.

  • Cleaning

While it is easy to submerge a regular thermometer in warm, soapy water, it is more difficult to do so with a digital thermometer. You have to be careful not to get a digital thermometer too wet or you will mess up the mechanical system, and it will no longer work.

Killing germs is very important when using your thermometer and disinfecting after using it rectally is also important. It is recommended you use cool, soapy water only on the tip of a digital thermometer. Some digital thermometers even come with disposable tips to help with this situation.

  • Digital Accuracy

Not all digital thermometers are as reliable as others. For example, you want to steer clear of using digital ear thermometers. At first glance, they do appear as the easier choice between taking a rectal temperature or having a fussy child hold a thermometer under his or her tongue. But sometimes, they do not register fevers at all, according to Liverpool University Institute of Child Health researchers. These thermometers can also have a one or two-degree difference compared to rectal or oral readings.

Types Of Medical Thermometers

No matter which type you choose, read the manufacturer’s instructions carefully. No thermometer will provide accurate results if it’s used incorrectly.

Never use a thermometer on a person that is meant for another purpose, such as a laboratory or meat thermometer. These won’t provide accurate readings.

If you’re a parent, you may be wondering why we’re omitting forehead strip thermometers from this roundup. Strip thermometers are inexpensive and quick to use. However, since they measure skin temperature rather than body temperature, they’re significantly less accurate and should be avoided.

  1. Oral thermometer

Oral temperature can be taken by either a digital or mercury thermometer. We’ll go over the benefits and drawbacks of mercury thermometers below.

The average oral temperature reading is 98.6°F (37°C). However, any oral temperature from 97°F (36.1°C) to 99°F (37.2°C) is considered typical. Some people run naturally cool, and others slightly warmer. It’s a good idea to know what your temperature typically is so you can assess whether you’re running a fever when you feel sick.


  • Oral thermometers are most accurate in children over 3 and in adults.


  • Small children and people with breathing issues may not be able to keep their mouths closed long enough to acquire an accurate reading.
  1. Digital ear (tympanic) thermometer

Tympanic thermometers measure the temperature inside the ear canal through infrared ray technology. Tympanic readings are 0.5°F (0.3°C) to 1°F (0.6°C) higher than oral temperature readings.


  • Tympanic thermometers provide fast and accurate readings and may be preferable to oral or rectal thermometers, especially in children.


  • Due to the size of the ear canal, tympanic thermometers aren’t recommended for infants under 6 months old.
  • They must be positioned properly to get accurate results.
  • Obstructions like earwax may skew results.
  • They may not fit properly in a small or curved ear canal.
  1. Forehead (temporal) thermometer

Forehead thermometers use infrared sensors to measure the temperature of the superficial temporal artery, which is a branch of the carotid artery.

Some are known as non-contact infrared thermometers. Forehead thermometers that require no physical contact have become very popular for use in venues such as airports, stores, and stadiums.

Forehead temperature readings run around 1°F (0.6°C) cooler than oral temperature readings.


  • Temporal thermometers provide quick readings, within several seconds.
  • They are easily administered and can be used on infants, children, and adults.
  • Some research indicates that temporal thermometers may be as accurate as rectal thermometers in children, and provide better readings than ear or armpit thermometers can. However, these findings aren’t conclusive and have been disputed in other studies’ Trusted Source.


  • Forehead thermometers must be positioned accurately and according to the manufacturer’s instructions, or they will not provide the right reading.
  • Readings can be affected by external factors, including drafts, wind, indoor heating, and direct sunlight.
  • Wearing certain clothing, such as hats or heavy coats, can skew the results.
  1. App-based thermometer

Most free phone apps designed to take temperature readings are meant for recording the temperature of environments, not people.

Phone apps that help with taking people’s temperatures rely on digital thermometers that link back to the app via Bluetooth connection.


  • Temperatures can be taken orally, rectally, or under the arm.
  • They provide readings within 8 to 10 seconds.
  • Some apps let you upload your anonymous temperature readings to a health and weather map, which can help make local authorities aware of illness spikes in your geographic area.
  • Some apps provide suggestions for medical next steps, based on the reading.
  • Most apps provide you with the ability to keep a log of multiple people’s temperatures.


  • Not every app or thermometer that connects to an app is reliable. Some manufacturers have better track records than others.
  • App-based thermometers may be significantly more expensive than digital thermometers without Bluetooth connectivity.


Digital thermometers are a popular option, which can be used orally, rectally, or under the armpit. Some no-touch forehead thermometers are also popular, especially in social settings.