can a smartphone be used as a thermometer

Can a Smartphone be used as a Thermometer?

Smartphones have become an integral part of our everyday lives, acting as not only communication gadgets but also entertainment hubs.

An intriguing possibility that comes up is whether or not a smartphone can be utilized as a thermometer to provide us with reliable measurements of the ambient temperature.

It is true that smartphones were not necessarily made for this function, but can you use them in that way as well? Really, can phones measure temperature?

Smartphones cannot measure temperature accurately on their own but a combination of built-in sensors, external accessories, and apps can help. 

A Bit about Smartphone Capabilities

a bit about smartphone capabilities

As well as calling someone, there seems to be no end to what an up-to-date Smartphone can do.

The latest models have wireless charging, large 6-inch plus screens and smaller overall sizes.

Multiple cameras are the new norm and 5G comes as standard. Smartphones are still evolving.

Future Smartphones will be made from the new highly flexible wonder material, graphene.

And they may also have tiny nano-tech batteries, liquid buttons, headphone surround sound and virtual reality.

Fact: Smartphones have the ability to superimpose digital data onto the physical world, allowing for novel methods of interacting with others. 

Can a Smartphone be Used as a Thermometer?

using a smartphone as a thermometer

In theory, yes, it is possible to use a Smartphone to measure temperature.

We have the sensors and we know how to use them. There wouldn’t even be difficulty fitting another sensor in although phones are getting smaller.

The problem lies with the Smartphone and the heat they produce which would be in close proximity to the sensor.

It would be almost impossible to get reliable readings but manufacturers are looking for ways around it. 

How Can Smartphones Be Used as a Thermometer?

Smartphones already have multiple thermosensors to monitor components, especially the battery which cycles through heating and cooling.

However, it is harder to use a Smartphone as an accurate thermometer to take the temperature of a room.

can smartphones be utilized as thermometers

It stays that way even if the Smartphone compensates for the impact of its own heat using clever algorithms.    

However, there are ways to use your smartphone as a thermometer.

And this depends mainly on the following factors:

  • Built-in Temperature Sensors
  • External Temperature Sensors
  • Smartphone Apps
Fact: Smartphones can store credit card information and enable contactless payments through technologies like NFC. 

Built-In Temperature Sensors

built-in temperature sensors

Although Smartphones have no air temperature sensor, every Smartphone has built-in temperature sensors.

When the battery is not being used, its temperature is stable, correlating well with ambient temperatures.

Researchers studying urban hotspots have developed their use taking body heat into account as they record temperatures as in or out of pocket. 

Ambient Temperature Sensors

Both Samsung and Motorola have had phones with ambient temperature sensors in the past. The device had to be left to cool before use.

The latest ambient temperature sensors are built into devices on Samsung’s Android platform.

They are capable of monitoring relative ambient humidity and pressure levels and levels of illuminance as well as ambient temperatures as a single value per event.

This makes the data simple to process and easy enough for any user to interpret. 

Internal Temperature Sensors (Battery and Processor)

internal temperature sensors

How much heat a phone generates depends on how it is used. Playing a game generates more heat than scrolling the news.

Smartphones have internal sensors to monitor the temperature of the battery and these produce data that, with adaptive algorithms, are used to estimate the ambient temperature of a room.

Because the data from internal sensors is very local, thermometer apps also use it to come up with good estimations of the ambient temperatures. 

External Temperature Sensors

The diffused heat generated by a Smartphone renders using its internal sensors to measure ambient temperatures a bit hit and miss.

Despite the algorithms, the readings will only ever be a good guess.

External temperature sensors overcome this and provide a way for the user to take readings that are accurate. 

Infrared Thermometer Sensors

infrared thermometer sensors

Infrared thermometers are generally accurate but because they use imaging to collect their data, they have trouble with surfaces.

Thermal imaging is essentially a heat-detecting sensor.

Called a microbolometer, this type of infrared thermal imaging sensor has recently, post-pandemic, been developed as an inexpensive component for use in any smartphone.  

Bluetooth Temperature Sensors

Many external temperature sensors support Bluetooth with apps that monitor temperature in real time.

Sensors can be linked to other devices and the data manipulated in various ways.

The user does not need to be at the location so farmers use Bluetooth sensors to monitor the ambient temperature of their barns.

Fact: Getting a reliable weather app that pulls information about the weather in your area from nearby weather stations or from the general public is always better. 

Smartphone Apps for Temperature Measurement

smartphone apps for temperature measurement

There are many smartphone apps for temperature measurement on the Android and iOS platforms.

One of the more reliable is the iThermonitor.

Smartphone temperature apps have developed for different kinds of thermometers, for example Fever Tracker measures body temperature by touching the screen.

Moreover, you can find other types of apps as well.

For instance:

  • Built-in System Apps
  • Third-Party Apps

Built-In System Apps

built-in system apps

It is usual for smartphones to come with built-in apps, some might seem pretty pointless and take up storage space however built-in temperature apps are vital.

They manage the device’s running temperature to prevent dangerous overheating, monitor the CPU, the health of the batteries, and the temperature of the motherboards. 

Third-Party Apps

Third-party apps are apps that are provided by someone other than the smartphone’s manufacturer.

They are the apps people download and there is no shortage of them.

Each app has a selection of features that allow you to manipulate the data and present it in different ways, as a graph for example.

These third-party apps often work in different ways.

For instance: 

Infrared Thermometer Apps
infrared thermometer apps

The third-party infrared thermometer apps, called pyrometers, were developed in response to the Covid 19 pandemic because almost everyone had access to a smartphone.

The various easy-to-use apps meant that individuals obeying social distancing rules could not only take their own temperatures accurately and more importantly, understand the results. 

Apps Relying on External Sensors

There is a plethora of third-party apps that provide less accurate temperature readings

They work by collecting data here and there from internal and external sources then applying compensating algorithms.

Apps that work directly with external temperature sensors are near accurate and work just as well on a desktop as they do on a Smartphone. 

Apps Using Crowd-Sourced Data
apps using crowd-sourced data

Smartphone apps have used crowd-sourced data to estimate the ambient temperature inside buildings.

This crowdsensing data is aggregated, collected from multiple Smartphones without the need for fixed infrastructures typically needed for environment and traffic monitoring.

Crowd-sourced data helps keep public transport running and lets people know the availability of parking. 

Limitations of Temperature Sensors

It is true that you can use your smartphone as a thermometer but it all depends on temperature sensors.

But, the problem is that many thermal imaging sensors cannot operate above 35°C.

limitations of temperature sensors

The smartphone industry is working to fix the situation because cheaper, more accurate and faster temperature sensing technology has serious applications in autonomous driving.

There is a reason to be wary of third-party apps accessing your phone’s internal sensors when all apps collect information about you.

Here are some other limitations of sensors used for temperature measurement:

Placement of Sensors

Achieving accurate and meaningful temperature readings depends on using the right sensor and its careful placement.

These considerations are important because these sensors measure just the temperature in the target area without interference, for example, from an open window.

To check new sensors are correctly positioned, the advice is to take several traditional thermometer readings.  

Sensor Calibration

sensor calibration

Sensors need calibrating. Sensor calibration is adjusting a sensor so that it functions as accurately as possible.

Calibration prevents errors occurring in the data making it inaccurate.

Sensors will need calibrating to ensure proper zero referencing, or to compensate for changes in the range of data or wear and damage. 

Environmental Conditions

Environmental sensors measure, monitor and detect environmental conditions or properties such as:

  • Relative humidity
  • Sound and noise levels
  • Luminosity
  • Atmospheric pressure
  • Dust
  • Temperature

These kinds of sensors require regular calibrating for optimal efficiency in the environmental conditions they are monitoring particularly when collecting reference samples. 

Use Errors

Besides poor placement and poor calibration, there are several reasons why a sensor may not be providing accurate data.

use errors

Common sensor faults, bias, drift, stuck-at, complete failure and precision degradation refer to the quality of the data.

User error is different, suggesting a mistake by the user.

Fact: Always calibrate your infrared thermometer or external sensor according to the manufacturer's recommendations. 


Can a smartphone be used as a thermometer?

Smartphones come with sensors to help measure the internal temperature.

But, it is still not possible to find a smartphone that can be used as an accurate thermometer.

However, you can still use a combination of internal sensors, external sensors, and some third-party apps to accurately measure temperature.