How to Check Room Temperature with or without a Thermometer

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The most accurate ways to find ambient temperature, plus the ideal temperature for your home
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You’ve got your thermostat set to 72 °F (22 °C), but you’re still feeling chilly. Now you’re wondering, “What’s the actual temperature of the room? Is my thermostat accurate?” Thankfully, there are a variety of tools you can use to measure room temperature (and you might have one of them in your pocket right now!). In this article, we’ll show you how to measure room temperature with your smartphone (using its internal thermometer or an external sensor) plus the best way to use 3 kinds of good old-fashioned thermometers. Now let’s see what the temp really is!

Things You Should Know

  • Check room temperature accurately with a smartphone by connecting to an external sensor or weather station .
  • Use digital , glass , or bimetallic thermometers by placing them in the center of the room (at least 2 ft (0.61 m) high) and reading them after about 5 minutes.
  • The recommended room temperature for healthy adults is between 64–75º F (18–24º C).
Method 1
Method 1 of 3:

Using Smartphone Sensors & Apps

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  1. Few smartphones have the right equipment to accurately read room temperature—their sensors only monitor the battery temperature and are affected by heat radiating from the phone. This means that thermometer apps can only give rough, often inaccurate estimates of room temperature unless they’re designed with a specific ambient temperature sensor. [1]
    • Some popular thermometer apps include Room Temperature Thermometer , HD Thermometer , and Real Thermometer .
    • Some phones with external temperature sensors are the Samsung Galaxy S4, Samsung Galaxy Note 3, Motorola Moto X, Huawei Ascend P6, and Xiaomi Mi3.
    • The number of phones with accurate sensors has been declining since it’s not a popular or easy to manufacture feature.
  2. Get an external temperature sensor or weather station for your phone. For accurate readings, connect your phone to an external thermometer. Look for devices that connect to WiFi or Bluetooth—many can also read humidity, air quality, and more. Then, download the accompanying app to your phone so you can read results and adjust settings from the palm of your hand. [2]
    • WiFi models are more expensive than Bluetooth ones, which can only work if your phone is within a certain distance of the sensor device.
    • External sensors and weather stations can also be connected to an Amazon Alexa or Google Home system if you have one.
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  3. Wait for the app to finish downloading, then tap on it to open it. Depending on the product, you may have to create an account to sync the device with the app. Make sure you’re connected to the same WiFi network as your external device if it uses WiFi. If it uses Bluetooth, connect your devices to enable use. [3]
  4. The app’s display will look different depending on which device you’re using, but the temperature reading will be easy to find. Make sure you’re looking at the room or ambient temperature and not the weather forecast. [4]
    • Adjust your settings to your preferred temperature system (Fahrenheit or Celsius), or convert the reading yourself if you feel like doing some math!
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Method 2
Method 2 of 3:

Using Traditional Thermometers

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  1. Try a digital thermometer for the most accurate temperature reading. Electronic and digital thermometers are pricier than other types, but they provide the fastest and most precise temperature readings. They react to air temperature changes very quickly, so you’ll always be confident in the current temperature. [5]
    • Some digital models store temperature data over a certain period of time so you can evaluate changes in the room’s temperature.
  2. Use a classic glass thermometer for approximate temperature readings. Opt for one that doesn’t contain mercury, since it’s highly toxic and dangerous if the thermometer ever breaks. [6] These thermometers use a glass tube (a capillary) with a liquid inside. As the temperature rises, the liquid expands and moves farther up the tube. [7]
    • These thermometers are slower to adjust to temperature changes than digital ones and can only provide an approximation of the ambient temperature.
    • Glass thermometers are also called bulb or liquid-in-glass thermometers.
  3. Try a bimetallic thermometer for a decorative or easy-to-read option. These thermometers have a display dial with a pointer (similar to a clockface) that moves to show you the temperature. They have a metal strip that expands and bends as the room temperature rises, which moves the pointer on the dial. [8]
    • The large pointer on the dial makes it easy to see the temperature from far away. However, bimetallic thermometers aren’t as accurate as digital ones.
    • Bimetallic thermometers can look relatively plain or be made to look like compasses, clocks, sundials, or feature other designs.
  4. This is the ideal spot to get an accurate reading since it’s sitting height for most people and away from the heat or cold of floors and walls. Make sure there are no drafts or heat sources near the thermometer, since these will throw off the reading.
    • Try setting the thermometer on a table or stool to keep it off the (usually cold) floor.
    • Keep the thermometer out of direct sunlight, which will produce a warmer reading.
  5. Back away from the thermometer so your body heat doesn’t influence the reading. Most thermometers, especially glass or bimetallic ones, will take at least several minutes to adjust to changing temperatures. [9]
    • Digital thermometers work fast and may show results in about 1-2 minutes.
  6. Leave the thermometer on the table so the heat from your hands doesn’t change the reading. [10] For most people, a comfortable room temperature is somewhere between 18–24º C (64–75º F). [11]
    • Digital thermometers: Read the numbers on the digital display to see the temperature. This reading is the most accurate.
    • Glass thermometers: Read the number or tick mark closest to the top of the liquid in the tube. Keep your eyes level with the top of the liquid for accuracy.
    • Bimetallic thermometers: Look at the number or tick mark that the pointer is pointing to, similar to how you would read an analog clock.
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Method 3
Method 3 of 3:

Ideal Room Temperatures

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  1. The World Health Organization (WHO) and other health groups recommend a minimum room temperature of about 64º F (18º C) for healthy adults who are appropriately dressed for the season. This range is ideal for rooms like living rooms, where people are largely sitting still while visiting or watching TV. [12]
    • For the elderly, very young, or the sick, raise the minimum temperature to about 68º F (20º C).
  2. Cooler temperatures are best for sleep since a decrease in temperature triggers your body to start feeling tired. Sleep psychologists suggest thinking of your bedroom as a “cave” to get great sleep —keep it cool, dark, and quiet. [13]
  3. This temperature keeps you comfortable when you get out of the shower or bath (stepping out into drastically colder temperatures can have negative impacts on your health). It’s also just a pleasant temperature whether you’re using the bathroom in the middle of the night or at any point during the day. [14]
  4. The U.S. Department of Energy suggests keeping your thermostat as high as comfortably possible in warm weather during waking hours. Lower your home’s temperature at night when you go to sleep for comfort, and set your thermostat slightly higher when you’re away for hours at a time to save energy. [15]
    • The smaller the difference between the indoor and outdoor temperatures, the lower your air conditioning bill will be.
  5. Save energy and money in cold months by keeping your home slightly cooler. When you’re asleep or away for long periods of time, lower your thermostat a few degrees. [16]
    • If you’re going away for days or weeks at a time in winter, keep your thermostat at a minimum of 50 °F (10 °C) to prevent your pipes from freezing and bursting.
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Community Q&A

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  • Question
    How to tell Fahrenheit?
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    This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.
    wikiHow Staff Editor
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    To convert temperatures in degrees Celsius to Fahrenheit, multiply by 1.8 (or 9/5) and add 32. However, most physical thermometers will show readings in both C and F, and digital thermometers or phone apps can toggle between the two in settings.
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  • Question
    If we only have contact thermometer, is it still okay to measure room temp by placing a glass of water and let it sit at room temp and then measure the temp of water?
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    This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.
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    Staff Answer
    Yes, but the water will have to sit for a very long time. It can take as long as 24 hours for water to adjust perfectly to room temperature (the smaller the amount of water, the faster it will acclimate).
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  • Question
    Can you use an iPhone 6 phone to measure room temperature?
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    Not very accurately, unless you connect it to an external temperature sensor or weather station. Most smartphones don't have the right hardware to take room temperature.
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      • If the temperature feels “just right” in a room, it’s probably somewhere between 72–76° F (22–24° C). This is the range where most people can radiate their body heat and keep their internal temperature at 98.6 °F (37.0 °C). [17]
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      References

      1. ↑ https://www.tandfonline.com/doi/full/10.1080/24751839.2019.1634869
      2. ↑ https://www.weatherstationadvisor.com/how-to-check-room-temperature-with-iphone/
      3. ↑ https://www.weatherstationadvisor.com/how-to-check-room-temperature-with-iphone/
      4. ↑ https://www.weatherstationadvisor.com/how-to-check-room-temperature-with-iphone/
      5. ↑ https://www.explainthatstuff.com/thermometers.html
      6. ↑ https://www.epa.gov/mercury/mercury-thermometers
      7. ↑ https://www.tec-science.com/thermodynamics/temperature/how-does-a-liquid-in-glass-thermometer-work/
      8. ↑ https://www.tec-science.com/thermodynamics/temperature/how-does-a-bimetallic-strip-thermometer-work/
      9. ↑ https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/qj.3817
      1. ↑ http://www.reachoutmichigan.org/funexperiments/agesubject/lessons/caps/thermometer.html
      2. ↑ https://www.zmescience.com/other/feature-post/not-too-hot-not-too-cold-whats-the-ideal-room-temperature/
      3. ↑ https://www.zmescience.com/other/feature-post/not-too-hot-not-too-cold-whats-the-ideal-room-temperature/
      4. ↑ https://health.clevelandclinic.org/what-is-the-ideal-sleeping-temperature-for-my-bedroom/
      5. ↑ https://www.zmescience.com/other/feature-post/not-too-hot-not-too-cold-whats-the-ideal-room-temperature/
      6. ↑ https://www.cnn.com/2019/08/20/health/thermostat-recommendations-energy-star-trnd/index.html
      7. ↑ https://www.energy.gov/energysaver/programmable-thermostats
      8. ↑ https://www.scientificamerican.com/article/why-people-feel-hot/

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