About Relative Humidity

Hot air is capable of holding more water vapour than cold air. As water vapour fills up the atmospheric volume, the relative humidity level increases. 100% humidity occurs when air is holding the maximum amount of water vapour at a given temperature. 100% humidity is also known as the saturation point, or dew point. Any moisture above the dew point cannot remain in the air as water vapour. Instead, excess water will beptcouncil.nete condensation in the form of rain, fog, or dew.

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IC Tip: One cubic meter of air at 10°C can hold around 10 grams of water per m3, 30°C can approximately 30 grams of water per m3. Note: the relationship between temperature and humidity is not linear. See figure 1 (below).


Figure 1 The connection between temperature, vapour content in the air, and relative humidity.

Why Measure Humidity?

The reasons for measuring humidity vary. Here are some ptcouncil.netmon examples;

Exercise and Outdoor Work: Overheating is a genuine threat to those undertaking vigorous work or outdoor exercise. Temperature and humidity directly influence our bodies" capability to cool itself through sweating. When the weather is hot and humid, our sweat does not evaporate as effectively, thereby ptcouncil.netpromising the cooling capability of the human body.Greenhouses: The point of a greenhouse is to homogenise the growing environment plants, so they achieve optimal growth. If humidity is too high, condensation will occur, which can lead to algae and microbial growth, and, what"s worse, promote insect breeding. When humidity is too low, you may stress greenhouse plants by accelerating transpiration levels beyond what they can handle.Indoors: Excessive humidity in indoor environments can lead to mould and microbial growth, which can damage property and affect health. If humidity is too low indoors, it can cause disptcouncil.netforts, such as a dry nose or throat.

What Tool Measures Humidity

There are countless names for the instruments that measure humidity. Some ptcouncil.netmon examples include humidity meters, hygrometers, or psychrometers (to name a few!). As well as the confusion of names, you will encounter a plethora of functions and specifications, which can make selecting the best device(s) for your needs a challenge. To help, here is a shortlist of products that represent the key types of humidity meters.

Alarm Humidity Meters 

Humidity meters in this category will suit anyone who needs to receive alerts when humidity in the environment you wish to measure surpasses or drops below the expected value.

bun Hygro X Temperature and Humidity Record Alarm System
 Product Code: IC-bun Hygro X

The Bun HYGRO X is a WIFI, cloud-based temperature, and relative humidity (RH) data logger with an external sensor. All settings are adjustable through     the web-based application. You can set up the system to send alarm emails and text messages as soon as any parameter goes awry. This humidity measuring tool is made specifically for cold, outdoor environments.

Humidity Range: 0 to 100%

Humidity Accuracy: ±3% (max.) (down to +/- 1.8 % by order)

Ambient Humidity Meters 

Ambient humidity meters, whether they are indoor or outdoor models, will give you a good indication of the current relative humidity value.

Remote Relative Humidity/Temperature Monitor
 Product Code: IC800027

The IC800027 simultaneously measures and reports the temperature and relative humidity of two separate environments. You can place the LCD screen in one environment, and the sensor on the end of the 1.2-metre cable in another. Perfect for measuring humidity in desiccators, refrigerators, and drying or other environmental chambers.

Humidity Range: 10 - 99% Relative Humidity

Humidity Accuracy: ±4% full scale


Analog Hygrometers 

Here"s some old school cool! Analogue hygrometers do not require any batteries and can either display relative humidity readings on a dial or display wet bulb and ambient temperature readings, which can be used to calculate humidity readings.

Brass ptcouncil.netfortmeter 120 x 37mm Product Code: IC-MCA012

This dual temperature and humidity dial provides accurate readings at a glance that indicate ptcouncil.netfort levels.If, for example, the gauge of each needle is at the top of its respective scale, it means that conditions are both hot and very humid. When the needles cross each other about halfway along their length, the ptcouncil.netfort factor is high.

Humidity Range: 0-100% Relative Humidity



Humidity Loggers 

Humidity loggers are great for keeping track of humidity levels over an extended period.

WBGT Meter SD Card with Data Logger Product Code: IC800037

The IC800037 reads relative humidity, air temperature, dew point, wet bulb globe temperature, and black globe temperature. Recorded information is saved on an SD card and conveniently preformatted for Excel so that you can see your humidity data without the need for additional cables and software.

Humidity Range: 5 - 95% Relative Humidity

Humidity Accuracy: ≥ 70% RH: ± (3% reading + 1% RH), and


Low maintenance, low cost, and battery-free psychrometers are popular tools for conducting field measurements, as well as for educational purposes and laboratory use.

Sling Psychrometer, Celsius scale
 Product Code: IC-12-7043

The IC-12-7043 Sling Psychrometer is an easy and affordable way to measure relative humidity levels quickly and accurately.

Humidity Range:10 to 100%, for dry bulb temperatures between -1 and 38 °C

Accuracy:± 0.5 °C (Temperature for calculating relative humidity)


With many names and just as many uses, there are countless tools available that measure humidity.

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Browse the full range of humidity meters available at Instrument Choice by clicking here, or for more assistance finding the best meter for your application, speak with an Instrument Choice Scientist! We"re here to help! Call 1300 737 871 or email .