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How to Check Body Temperature with iPhone

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Maja Nowak

Updated onAugust 7, 2023

Have you ever wondered how to check body temperature with an iPhone?

As you know, iOS offers a lot of useful applications. There are apps you can use to talk to when you’re bored, tools to transform your voice in an unconventional way or apps where the main character is a woman who does nothing but look at you. However, as body measuring equipment becomes more and more popular, we begin to expect something more from our smartphones. Research shows that we start to think about our health more often and business or entertainment applications are becoming less important. This is certainly in part a result of the pandemic.

Moreover, it is more and more often the case that smartphone manufacturers install sensors capable of measuring parameters that in the past could be only measured by separate devices, for example, heart rate monitors or oximeters. Galaxy Note 4, for example, is a smartphone that can measure your blood oxygen saturation, which makes it a convenient tool for estimating your SpO2. It’s a wonderful news for us all, since we are so strongly attached to our phones and now they can also act as our personal doctors.

Okay, but what about the measurement of body temperature?

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Reading Temperature With an iPhone

Unfortunately, it's not that simple. The iPhone itself does not have a built-in thermometer that could be used, for instance, to measure fever.

Fortunately, there are intermediary solutions. In June 2023, we received electrifying news from the University of Washington. A team of researchers led by this university has created an application - FeverPhone - that transforms smartphones into thermometers without the need for external accessories. You only need to place the smartphone screen on the patient's forehead.

FeverPhone App

How Does FeverPhone Work? AI, AI, AI, ...

The app uses the phone's touch screen and battery temperature sensors to collect data, which a machine learning model then uses to determine body temperature. According to the creators, FeverPhone estimates the average body temperature of patients with an error of about 0.23 degrees Celsius, which is within the clinically acceptable error range of 0.5 degrees Celsius.

Although the app still needs more training data, the potential of such technology is exciting for doctors. Above all, FeverPhone is easy to use - just place the phone screen on the forehead and wait for results. It is also more hygienic, as there is no need to use traditional thermometers that must be thoroughly cleaned after each use.

Reading Temperature With Accessories or External Sensors

Other popular methods of reading body temperature with an iPhone involve using the audio port or Bluetooth™ technology.

Whishbone Optical Thermometer

In the first method you connect a thermometer to the headphone port. An example of such a thermometer is Wishbone. First, connect the thermometer to the headphone port, next install a dedicated application and then place the device onto the forehead.

Optical temperature sensor Whishbone

According to its manufacturer, Wishbone is a smart thermometer that allows you to quickly and easily measure your child’s temperature.

The latest Apple phones do not have a headphone jack which is why Bluetooth™ technology has been used more and more often in external thermometers which send measurements to smartphone screen in real-time. The market offers several solutions that differ with the method of application and accuracy.

Withings thermometer

Body temperature is most often measured by taking the highest temperature reading on the temple. Such a measurement is taken by Withings Thermo. It is a medical grade product that automatically synchronizes measurement results with dedicated Health Mate app.

Withings thermometer

At first sight, Withings Thermo looks like a classical thermometer, yet the difference is significant. Its 16 infra-red sensors provide instant temperature reading from temporal artery which is considered an area which temperature correlates most closely with body temperature (taking into account forehead readings, of course).

Chest Temperature Monitor

Another interesting method of measuring temperature is using Aidmed One. It is a chest wearable sensor that can measure your temperature on an ongoing basis. It is all the more important insofar as only a 24-hour temperature measurement may reveal significant trends: Is the fever subsiding? Is it possible that I feel worse because the low-grade fever is returning?

Additionally, the measurement itself does not have to be limited to merely transferring health data. When we exercise, our body starts to heat up significantly and long overheating can have negative effects. Detecting this will be possible only if temperature is continuously monitored.

Chest-worn temperature monitor

Aidmed One takes readings directly from the chest. This area is close to heart which is why there is blood circulation there that allows very precise measurements.


To sum up, in order to enable iPhone to measure body temperature, it must be integrated with external sensors. Some of the solutions enable a simple and quick scan of the temple without a necessity of touching the skin. Others, however, have benefits that could not be obtained with use of conventional methods.

Finally, it is worth to mention a whole range of applications which can be used to record the measurements. Body Temperature Recorder is an example here. Its main functionality is saving temperature measurements from previous days. You can also draw trend lines to see how your body temperature changes over time. It’s also possible to record symptoms such as muscle soreness or sore throat that you can feel when your body temperature is increased.

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