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What is a Psychrometer?

The word “Psychrometer” is unfamiliar to most of the people. It is familiar to those who know about the tools. There are a bunch of different tools that measure the relative humidity in the atmosphere. Relative Humidity refers to the number of water vapors in the atmosphere. There is something that confuses many people regarding the psychrometer and hygrometer. “What is a psychrometer” is the first question that comes to mind whenever someone hears about psychrometer.

What is a Psychrometer?

A psychrometer is a type of hygrometer that measures the relative humidity in the atmosphere. It is different in shape than the hygrometer. Similarly, it is composed of two thermometers: dry and wet bulb thermometers. Dry bulb thermometer uses its dryness and exposure for the measurement of temperature. Whereas, wet-bulb thermometer measures temperature as the bulb dipped into the water. Both thermometers are vital to measuring the relative humidity. Two bulbs of both thermometers are connected with each other. However, precautionary measures must be taken while calculating the relative humidity.

It is important to note that psychrometers are based on traditional method. However, digital psychrometers are now available in the market. Digital Psychrometers is more accurate. However, they work with the power supply. In this article, we will talk about the traditional measurement method. You can also check What is the Humidity Today.

How to measure humidity with Psychrometer?

Sling Psychrometer consists of two bulbs of thermometers. Traditional Psychrometers also known as Sling Psychrometers. Psychrometer works on the base of the evaporation and cooling process. After removing the wet-bulb from the water, the bulb starts cooling down and water starts evaporating. Therefore, the cooling of the bulb estimates the amount of water evaporating. In most cases, the wet-bulb hardly changes its temperature. The little evaporation of water gives us the estimation. Evaporation takes place at a faster rate if the air is dry. As a result temperature of the wet-bulb drops significantly.

The maximum time to swing the hydrometer in the room is approximately one minute. After this interval time, the period temperature must be noted for both bulbs. The difference between the temperature of both bulbs is recorded. Let’s suppose the temperature of dry bulb = 38°C and wet bulb = 28°C. A graph is drawn where the y-axis shows the dry-bulb temperature and the x-axis shows the difference between both temperatures. The point where both axes meet each other gives the relative humidity. As this process is complicated, it demands practice. Therefore, an individual must be experienced enough to calculate the relative humidity. It is a good practice to measure the reading twice. In this way, there will be no confusion in the readings.

Uses of Psychrometer:

Many people prefer digital hygrometers because of the automatic system. However, psychrometers still in use in various areas over the world.

  • Psychromters are the part of ships as an alternative temperature and humidity sensor
  • Also used in Coating Industry to measure the paint sensitivity to temperature
  • Many instruments come to market with pre-installed psychrometer (Guitar, Piano, and Violin)

Psychrometer has two different types: the sling psychrometer and the aspirating psychrometer. Sling Psychrometer is also the general psychrometer and it has two bulbs. A handle controls the sling psychrometer. As discussed before, it has two thermometers. One thermometer is wet and the other one is dry. Therefore, Sling Psychrometer is considered a manual device. On the other hand, the aspirating psychrometer is battery powered. It is similar to battery-powered hygrometer.

How to measue humidity

Difference Between a Hygrometer and a Psychrometer

Many people face problems when it comes to understanding both devices. Although, both perform the same task but different in design. Moreover, both use a different method to measure humidity. 

In reality, there is no difference between hygrometer and psychrometer. A psychrometer depends on the oldest method to measure humidity. However, hygrometer uses a totally new digital approach.  When it comes to using a hygrometer or psychrometer, the priorities of the department vary. For example, weather stations use psychrometers. However, at home, a hygrometer is a good choice.

The choice of using either hygrometer of a psychrometer depends on the need. For common people, it is better to use a hygrometer or aspirating psychrometer. However, one should also know how to calibrate a hygrometer to get an accurate reading. 

Best Psychrometer to buy in 2022

If you are looking to buy a digital psychrometer then always focus on quality and price. Below is one of the best and cheapest psychrometer that you can buy easily on Amazon. Although, many psychrometers are available to purchase online but we get the best one for you.

Digital Psychrometer Thermo-Hygrometer

Digital Psychrometer Thermo-Hygrometer, LCD Mini Temperature and Humidity Meter with Dew Point have multiple features. It is a complete psychrometer and hygrometer. It uses the latest technology and helps the users to measure relative humidity.


  • An ideal psychrometer to use in industries such as Agriculture
  • Measure the relative humidity in seconds with the latest technology
  • Dual display of both temperature and hygrometer with 0.1% error
  • Data Hold and Auto Power Off Feature
  • Your first choice to get the best results

Product Details

  • Weight: 143g
  • Power: One standard 9V, NEDA 1604 or 6F22 battery
  • Sampling Rate: 2.5 samples per second
  • Display: Large 4-1/2 dual digital LCD display


  1. Measures both temperature and humidity instantly
  2. Fast response time without any hassle
  3. BIG LCD Display that works in both day and night
  4. An ideal choice for accurate measurements
  5. Two in one sensor to use in various industries


  1. It works with a battery power of 9V and no concept to use without battery
  2. The sensor doesn’t work in the presence of light
  3. Working in extreme conditions affect the accuracy of measurements
  4. Recovery takes a lot of time in the normal environment

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