Updated December 2021
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Buying guide for Best smart thermometers

A thermometer is a key piece of first aid equipment to have in the home. Monitoring your temperature can help you gain a head start on treating an illness and help you track your recovery. The design of thermometers has come a long way from glass tubes filled with dangerous mercury. Today’s thermometers have digital screens that provide fast, clear readings.

The next step forward is smart thermometers, which can store data about your temperature readings and share it with your smartphone through a Bluetooth connection. A smart thermometer’s app will track your health data so you can refer to it while monitoring the progression of an illness. You even can share this data with your doctor to help with your diagnosis.

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If you have a fever, the backlight on the smart thermometer’s screen may change from a green color to yellow, orange, or red. Other times the screen may display a warning icon when detecting a fever.

Key considerations

As you’re comparing different smart thermometers, the main consideration is whether you want a thermometer that measures body temperature or environmental temperature.

Body temperature

For measuring body temperature, think about how you’d like the smart thermometer to work as well as the level of accuracy you require.

  • Armpit: An armpit thermometer will deliver a quick reading, but it typically yields the least accurate results. Some manufacturers of smart thermometers indicate temperatures taken in the armpit register about one degree lower than the person’s actual temperature.
  • Ear: An ear thermometer has a reasonable accuracy level, although an excessive amount of earwax can throw off the reading. Do not use an ear thermometer on a child six months old or younger. If you want a general idea of a person’s temperature, an ear thermometer works fast and is only minimally uncomfortable. But these thermometers are not as precise as other options.
  • Forehead: A forehead thermometer returns a reading within a few seconds, using infrared scanning. It has a high level of accuracy, especially for small children. It’s not quite as accurate as a rectal thermometer, but it’s far easier to use. Unless a doctor specifically tells you to take a child’s temperature rectally, a forehead thermometer is a more than adequate substitute.
  • Oral: An oral thermometer is extremely accurate, delivering results in a short amount of time. However, do not take your temperature orally within several minutes of eating or drinking. Very young children may struggle to hold an oral thermometer in the proper position in the mouth for an accurate reading.
  • Rectal: A rectal thermometer is very accurate, but it can cause discomfort. For the most accurate temperature reading for a baby or toddler, doctors often recommend a rectal thermometer reading. Once you’ve used a smart thermometer rectally, be sure to disinfect it and only use it as a rectal thermometer in the future.

Smart thermometers are available in any of these designs, and many are usable in more than one way.

Environmental temperature

Other types of smart thermometers are made to measure the temperature in the immediate area, such as inside a room.

  • Smart thermostat: A smart sensor that measures the temperature in a room can work with a smart thermostat, adjusting the thermostat’s settings based on temperature readings.
  • Room monitor: Another type of smart temperature sensor is made to work in a baby’s nursery. These baby monitors measure the room temperature and send you an alert on a smartphone app if the temperature moves outside the specified range.
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Did you know?
Smart thermometers are typically made of durable plastic, rather than glass or metal.


Once you’ve settled on a type of smart thermometer, you will want to pay attention to the features of both the thermometer and its associated app.


The majority of smart thermometers use a Bluetooth connection to share data with an app. However, just because a thermometer calls itself “smart” does not mean it can share data with an app or has an app available. Always confirm that a smart thermometer has an app before selecting it.

A smart thermometer’s app may provide limited health advice based on your temperature readings, too, such as whether you should try over-the-counter medication for an illness or visit a doctor.

Ovulation monitoring

A common use for smart thermometers is tracking ovulation for women who wish to become pregnant. The smart thermometer sends its readings to an app, which creates charts to show the user the likelihood of ovulation occurring.

Data storage

Each smart thermometer is a little different, but you can expect the thermometer to save up to 20 past readings on the device itself. If you have the smart thermometer connected to your smartphone, you can keep track of an almost unlimited number of readings.

Apps should also save the date and time of readings to simplify the process of tracking temperature readings over time. With the majority of apps, you can assign a particular temperature reading to a certain family member, making the tracking process even more useful. With some apps, you can enter temperature readings manually, just in case you use a different thermometer to take a temperature.

Display screen

The small display screen on a smart thermometer will give you some information but not as much information as what you’ll find on the app. The thermometer’s display screen will show the temperature reading, and it may change color to alert you to abnormal readings.

It can be extremely helpful to have a backlit display screen so you can see the temperature reading in the dark. If your little one is sick, being able to take a temperature reading in the middle of the night without turning on an overhead light is handy.

Certain smart thermometers do not have a display screen, so you must connect to the app to see the readings.

"The majority of smart thermometers can display temperature readings in either Fahrenheit or Celsius, allowing you to set your preference."

Smart thermometer prices

When choosing a smart thermometer, you can expect to pay $20 to $100, depending on the smart features included. Thermometers with a greater number of smart features cost $50 to $100.

The only ongoing cost you should have with a smart thermometer is replacing the battery, which should cost just a few dollars every six months or so. The app associated with the smart thermometer should be free, although some apps may have in-app payment available to unlock certain features.


If you find that you’re receiving inaccurate results with your smart thermometer, it may be because you’re using it incorrectly. Here are some tips for using a smart thermometer for the most accurate readings.

  • Avoid readings after certain activities. You should not use a smart thermometer for several minutes after eating, exercising, bathing, or drinking, or it may give you an inaccurate reading.
  • Allow the thermometer to reach room temperature. If the thermometer has been in your car during extreme temperatures, don’t use it until you are indoors and the device has returned to a normal room temperature.
  • Place it properly in the mouth. If taking an oral reading, place the tip of the smart thermometer underneath the tongue at the back of the mouth.
  • School-age children can take oral temperature readings. Typically, a child around four to five years old is ready to hold the smart thermometer under the tongue properly for an oral temperature reading. Younger children will struggle with this.
  • Use rectal readings for babies and toddlers. When taking a rectal temperature reading on a baby, only insert the tip of the smart thermometer between one-half and one inch.
  • Remove clothing for underarm readings. If using the smart thermometer for an underarm reading, move the clothing so there’s nothing between the thermometer and the skin.
  • Always run updates. If you’re having problems connecting the smart thermometer to your smartphone, upgrade both devices to the latest versions.
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When cleaning a smart thermometer, use mild soap and warm water or alcohol wipes. Do not boil the tip of the smart thermometer or run it through a dishwasher cycle.


Q. How quickly does a smart thermometer work?
A smart thermometer should return an accurate reading within two to 10 seconds. Some thermometers take longer, especially for underarm readings. If you are using the thermometer incorrectly, one clue is that it may take longer than expected to return a reading.

Q. What should I do with an old mercury thermometer?
Glass thermometers with mercury in them used to be the only option for taking temperature readings. But because mercury is a toxic substance, such thermometers are no longer recommended for usage in the home. Do not throw away an old mercury thermometer that you’ve replaced with a smart thermometer. It needs to go to a hazardous waste collection site.

Q. Can I use one smart thermometer for my entire family?
You can. Just be certain you associate the reading in the app with the right family member. Always sanitize the smart thermometer after each use. Never use the thermometer for a rectal reading for a baby and then switch to an oral reading for another family member, even after sanitizing it.

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