How to accurately measure room temperature: 2 tips using a phone and a thermometer.

When your air conditioner is set to 22°C but you still feel colder or hotter than usual, it's very likely that the actual room temperature is different from the displayed temperature. In this situation, many people need to check the room temperature to know exactly whether their living environment is truly comfortable.

In this article, you'll learn the easiest ways to measure room temperature : using a smartphone , using a separate sensor , and traditional thermometers that have been trusted for a long time. All instructions are concise and practical, helping you quickly determine if your room is cool, cold, or too hot – allowing you to adjust accordingly for comfort and energy savings.

How to accurately check room temperature

Measure room temperature using your phone.
You can use your smartphone to check the room temperature when connected to an external measuring device.

• Connect your phone to a separate temperature sensor or indoor weather station.

• Open the device's app to view the room temperature in real time.

• This method offers high accuracy because the sensor device is optimized for environmental measurement.

Use a traditional thermometer to measure room temperature.
The three most common types of thermometers are digital thermometers, glass thermometers, and bimetallic thermometers.

• Place the thermometer in the center of the room, about 60 cm from the ground, to minimize inaccuracies.

• Avoid placing it near windows, doors, fans, or air conditioners.

• Wait about 5 minutes before reading the result to get a more accurate room temperature.

The ideal room temperature for adults.

• The recommended temperature range is 18–24°C (64–75°F).

• This setting is suitable for most adults, promoting comfort, stable sleep, and energy savings when using air conditioning.

Tip 1: How to measure room temperature using a smartphone

Step 1: Notes when measuring room temperature using a thermometer app on your phone.

Thermometer apps on phones are often inaccurate.
Most smartphones today do not have sensors to measure ambient temperature .

• The internal sensors only monitor battery temperature , so they are easily affected by the heat emitted from the phone itself.

• Therefore, thermometer apps on iPhones or Android devices only give estimated results, which are often significantly different from the actual room temperature.

• Only when the phone has a dedicated environmental sensor will the app be able to take more accurate measurements.

Some common thermometer applications

• Room Temperature Thermometer

• HD Thermometer

• Real Thermometer

These apps are suitable for quick reference but should not be used as a basis for accurate room temperature measurements.

These phone models used to have sensors to measure ambient temperature.

• Samsung Galaxy S4

• Samsung Galaxy Note 3

• Motorola Moto X

• Huawei Ascend P6

• Xiaomi Mi3

The number of smartphones with actual temperature sensors is decreasing because this feature is difficult to manufacture and few users need it.

Step 2: How to use a separate temperature sensor to accurately measure room temperature.

Connect your phone to a temperature sensor or mini weather station.
For much more accurate results than a thermometer app, you should use a separate temperature sensor or weather station connected to your phone.

• Choose a device that supports WiFi or Bluetooth for direct data transfer.

• Many sensor models can also measure humidity , air quality , outdoor temperature , etc., helping you comprehensively monitor your living environment.

• Download the accompanying app to view real-time data and customize settings directly on your phone.

Advantages and disadvantages of the two types of connections

• WiFi devices: more expensive but allow you to view data from anywhere, even if you're not near the sensor.

• Bluetooth devices: cheaper, but the phone needs to be close to the device to connect.

Extended functionality when using external sensors.

• Many models can connect with Amazon Alexa or Google Home , allowing you to view room temperature by voice or sync with your smart home system.

Step 3: How to open and synchronize the temperature sensor app

Open the app that comes with your temperature sensor or weather station.
After downloading the app to your phone, you need to open and sync it to see the room temperature .

• Tap the app icon after installation is complete.

• Some devices require you to create an account to synchronize and save data.

• Follow the on-screen instructions to connect the device for the first time.

Connect correctly according to the type of device you are using.

• If the sensor uses WiFi , make sure your phone and the device are on the same WiFi network.

• If the sensor uses Bluetooth , turn on Bluetooth on your phone and hold the device close to connect.

• Wait for the app to recognize the device and display the room temperature in real time.

Note: For more accurate room temperature measurements.

• Check that the device is placed in a well-ventilated location, away from direct sunlight and air conditioners.

• Maintain a stable connection to prevent data interruptions.

Step 4: How to view room temperature in the sensor app

Access the app's home screen.
Once the device is connected, you can view the room temperature directly in the app interface.

• Open the app and go to the home screen or the temperature display section.

• Each brand has a different interface, but the room temperature indicator is usually located in a very visible position.

• Make sure you check the correct room temperature (ambient/room temperature) setting, and avoid confusing it with the weather forecast .

Choose the appropriate unit of measurement.

• Customize the unit of measurement in the settings: Celsius (°C) or Fahrenheit (°F) .

• If the app doesn't support conversion, you can quickly convert it yourself using a common formula.

Tips for more accurate tracking

• Position the sensor in a fixed location to ensure stable data.

• Familiarize yourself with the app interface to quickly access room temperature at any time.

Tip 2: How to use a thermometer to check room temperature

Step 1: Use an electronic thermometer to measure the room temperature as accurately as possible.

Advantages of electronic thermometers
Electronic thermometers are the most reliable option when you need to measure room temperature accurately .

• It responds quickly to changes in air conditions, providing almost instantaneous measurements.

• Higher accuracy compared to glass thermometers or bimetallic thermometers.

• Stable operation, minimally affected by surrounding environmental factors.

Extended features of some electronic thermometer models

• Recording temperature data hourly or daily helps you track changes in room temperature over time.

• Some devices also display humidity levels or warn you when the temperature exceeds a threshold you've set.

When should you choose an electronic thermometer?

• When you need high precision to control the environment in a bedroom, children's room, or office.

• When you want to review the temperature history to adjust your air conditioner, heater, or ventilation more effectively.

Step 2: Use a glass thermometer to measure the room temperature as an approximate value.

How glass thermometers work
Glass thermometers (also known as bulb thermometers or liquid thermometers ) use a thin glass tube containing liquid inside.

• As the temperature rises, the liquid expands and rises in the tube.

• As the temperature decreases, the liquid contracts and sinks.

• This is a traditional measurement mechanism, simple and easy to observe with the naked eye.

Important considerations when choosing a glass thermometer.

• Choose a mercury-free thermometer, as mercury is toxic and dangerous if it breaks.

• Prioritize using colored alcohol or safe liquids to avoid risks to your family.

Advantages and disadvantages of glass thermometers

• It only gives estimated results , not as accurate as an electronic thermometer.

• It reacts more slowly to changes in air temperature, so you'll need to wait longer for a stable reading.

• Suitable when you only need to refer to the room temperature at an approximate level and don't require detailed data.

Step 3: Use a bimetallic thermometer when you need one that is easy to read or for decorative purposes.

How bimetallic thermometers work
Bimetallic thermometers use a double metal strip inside.

• As the room temperature increases, the metal strip expands and bends.

• This bending causes the needle on the clock face to rotate to the corresponding temperature.

• Looking at the needle, you can immediately know the room temperature without any further action.

Advantages of bimetallic thermometers

• Easily visible from a distance thanks to its large dial and prominent hands.

• No batteries required, unaffected by electronic interference.

• There are many styles: compass-like, clock-like, sundial-like… suitable for decorating living rooms, offices or shops.

Disadvantages to note

• Their accuracy is not as high as electronic thermometers; they are only suitable for quick reference.

• Its slower response to temperature changes makes it unsuitable for intensive monitoring needs.

When should you choose a bimetallic thermometer?

• When you want a device that's easy to observe , and can be viewed even from a distance.

• When you prioritize aesthetics , decoration, or need a simple measuring device that doesn't rely on a power source.

Step 4: How to position the thermometer in the room for accurate readings.

Place the thermometer in the center of the room.
This method reduces errors and accurately reflects the actual room temperature .

• Place the thermometer in the middle of the room , not too close to a wall or corner.

• Keep away from drafty areas such as windows, doors, or fans.

Keep the thermometer at a minimum height of 60 cm.
This height is equivalent to the human sitting position, which helps to stabilize the measurements.

• Place the thermometer on a table , shelf , or stool to avoid the cold air from the floor.

• Do not place the thermometer directly on the floor because the floor is usually colder than the air.

Avoid direct sunlight and heat sources.
Light or heat-emitting devices can distort the results.

• Avoid placing it near a window where sunlight shines in.

• Avoid placing it near air conditioners, heaters, or other operating electrical appliances.

Step 5: Wait for the thermometer to stabilize before reading the result.

Allow the thermometer to acclimate to room temperature for about 5 minutes.
Most thermometers need time to stabilize before displaying the correct room temperature .

• After placing the thermometer in the correct position, wait at least 5 minutes for the device to acclimate.

• Avoid standing too close, as body heat can skew the results.

• Glass and bimetallic thermometers typically take longer to react to changes in air temperature.

Electronic thermometers display readings faster.

• Electronic thermometers typically provide results in just 1–2 minutes and are highly reliable.

• If you need to monitor room temperature regularly or want quick results, an electronic thermometer is a more suitable option.

Step 6: How to correctly read room temperature readings

Do not handle or touch the thermometer when reading the result.
Keep the thermometer on a table or shelf so that the temperature from your hand doesn't distort the reading.

• Make sure you stand a little distance away so that your body heat doesn't affect the room temperature.

• This is a crucial step to obtaining the most accurate measurement results.

The room temperature is considered comfortable.

• Most adults feel comfortable within the range of 18–24°C (64–75°F) .

• If the room temperature is outside this range, you may consider adjusting the air conditioner, heater, or ventilation.

How to read each type of thermometer

Electronic thermometer

• Look directly at the number displayed on the screen .

• This is the most accurate result, least susceptible to environmental factors.

Glass thermometer

• Position your eyes level with the top of the liquid column in the tube.

• Read the number or mark closest to the top of the liquid column to determine the room temperature .

• Avoid looking from above or below to prevent getting the wrong angle.

Bimetallic thermometer

• Observe the hands on the clock face.

• Read the number or mark that the hands are pointing to, similar to how you would read a traditional analog watch.

Tip 3: Ideal room temperature for sleep and health

Question 1: What is the ideal room temperature to maintain in a house?

Keep most rooms at 18–24°C (64–75°F).
This temperature range is considered suitable for most adults and is recommended by many health organizations, including the WHO.

• 18°C is the minimum temperature for healthy adults when wearing appropriate seasonal clothing.

• This is the ideal temperature for the living room or family room – where people often sit, relax, watch TV, or chat.

Adjust the temperature higher for sensitive individuals.
Some groups need to be kept warmer to avoid health problems.

• The elderly.

• Young children.

• People who are sick or have weakened immune systems.
  In these cases, the minimum temperature should be raised to around 20°C (68°F) to ensure safety and comfort.

Tips for maintaining a stable room temperature

• Regularly check the room temperature using a reliable measuring device.

• Minimize drafts and adjust air conditioning/heating settings throughout the day.

• Ensure the room is well insulated to avoid sudden temperature fluctuations.

Question 2: What is the ideal bedroom temperature for deeper sleep?

Keep the bedroom temperature between 15–19°C (60–67°F).
Cool temperatures help the body feel sleepy more easily because body temperature naturally decreases when entering the resting phase.

• This temperature is recommended by many sleep experts because it helps you fall asleep faster.

• If the room is too hot or too cold, the body has to adjust a lot, making it difficult to fall asleep or sleep soundly.

Why should bedrooms be "as cool as a cave"?
Experts often suggest imagining the bedroom as a "small cave" :

• Cool temperatures help stimulate the natural sleep mechanism.

• Nighttime allows the brain to release melatonin more consistently.

• Keep it quiet to minimize waking up in the middle of the night.

Tips for maintaining a stable bedroom temperature

• Adjust the air conditioner to a low but moderate setting, avoiding making the room too cold.

• Use blackout curtains and close the windows to keep the room cool.

• Check the room temperature with an electronic thermometer to know the actual level.

Question 3: What should the bathroom temperature be maintained at?

Keep the bathroom warmer, around 22°C (71°F).
Bathrooms need a higher temperature than other rooms so you don't get a sudden chill when you step out of the shower or bathtub.

• The large temperature difference between warm water and cold air can be detrimental to health.

• 22°C helps the body maintain a comfortable state, especially when using the bathroom at night or early in the morning.

Why should bathrooms be warmer?

• After a warm bath, the body is very sensitive to cold air, easily causing shivering, vasoconstriction, or discomfort.

• A warmer environment also reduces excessive condensation, helping to keep the bathroom less humid and cleaner.

Tips for maintaining a stable bathroom temperature

• Close the bathroom door to prevent cold drafts from coming in.

• If using a water heater with a fan heater, turn it on a few minutes beforehand to allow the environment to warm up gradually.

• Avoid opening windows when it's cold because drafts will cause the temperature to drop quickly.

Question 4: What is the ideal temperature setting for energy saving in the summer?

Keep your home temperature around 26°C (78°F) to reduce your electricity bill.
During the hot season, setting the air conditioner temperature a little higher is a significant way to save on cooling costs while still maintaining comfort.

• Many energy agencies recommend a temperature of 26°C as it is suitable for daytime activities.

• When sleeping, you can lower it slightly to make it easier to fall asleep.

• When you're away from home for extended periods, set your air conditioner a little higher to reduce electricity consumption.

Why does setting a higher temperature help save energy?

• The smaller the temperature difference between the inside and outside of the house, the less the air conditioner needs to work.

• Reducing the load on your air conditioner means lower electricity bills and a longer lifespan for the appliance.

Tips for optimizing electricity bills during the summer.

• Use a fan in combination with an air conditioner to increase the feeling of coolness without drastically lowering the temperature.

• Keep doors and curtains closed during peak hours to limit heat from entering.

• Regular air conditioner maintenance helps the cooling device operate more efficiently with less electricity consumption.

Question 5: What is the ideal temperature setting for energy saving in winter?

Maintain daytime temperatures around 20°C (68°F).
During the cold season, maintaining your home temperature at 20°C will keep you warm enough while saving energy.

• This temperature is suitable for daytime activities while the body is still active.

• When going to bed or going out for an extended period, you can lower the temperature by a few more degrees to further save electricity.

For long trips lasting several days: maintain a minimum temperature of 10°C (50°F).
If you're leaving home for a few days or weeks in the winter, you shouldn't turn off the heating system completely.

• The temperature should be kept at a minimum of 10°C to prevent the pipes from freezing and cracking.

• This temperature is low enough to save electricity while still ensuring the safety of the household water system.

Tips for saving electricity in winter

• Close the doors and windows and use thick curtains to minimize heat loss.

• Wear several layers of warm clothing indoors so you don't need to set the temperature too high.

• Inspect and maintain the heating system to ensure the machine operates more efficiently.

The most comfortable temperature range for most people.

If you feel it's "just right," the room temperature is usually around 22–24°C (72–76°F).
This is the temperature range within which most of the human body can naturally radiate heat and maintain a stable body temperature around 37°C .

• When the room temperature is within this range, you generally won't feel too hot or too cold.

• This temperature range is also ideal for light activities such as reading, working, watching TV, or daily routines.

Why is a temperature of around 22–24°C considered the most comfortable?

• The body doesn't need to expend much energy to regulate its temperature.

• A stable circadian rhythm helps you feel more relaxed and focused.

• Suitable for most adults in normal living environments.

References

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5. https://www.tec-science.com/thermodynamics/temperature/how-does-a-liquid-in-glass-thermometer-work/
6. https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/qj.3817
7. http://www.reachoutmichigan.org/funexperiments/agesubject/lessons/caps/thermometer.html
8. https://www.zmescience.com/other/feature-post/not-too-hot-not-too-cold-whats-the-ideal-room-temperature/
9. https://www.who.int/news-room/fact-sheets/detail/climate-change-heat-and-health
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Translated by: Rowan Hudson Le .