All You Should Know About Hygrometers

A hygrometer is an instrument commonly used to determine the moisture content or the humidity of the air. This is a very simple to use tool for measuring the amount of humidity that exists in the atmosphere.

Hygrometers are used to measure the relative humidity and can offer an advanced warning on whether or not the heat or cold will be more severe due to humidity.

You can use those tools to help improve growing conditions in greenhouses and more. They are advanced tools that can accompany any weather forecast that you may tune into.

Types of hygrometers

There are many types of hygrometers available nowadays.

Classical types:

  • Ancient hygrometers
  • Metal-paper coil type
  • Hair tension hygrometers
  • Psychrometer (wet-and-dry-bulb with thermometers)
  • Sling psychrometer
  • Chilled mirror dew point hygrometer

Modern age types:

  • Capacitive
  • Resistive
  • Thermal
  • Gravimetric
  • Optical

However, they may be divided into three main categories – dry and wet bulb psychrometers – mechanical hygrometers – Electrical hygrometers.


Psychrometers consists of two thermometers. One of them /dry bulb/ measures the temperature in the air, the other /wet bulb/is used to determine the drops in temperature and absolute air humidity.

The relative humidity is established by comparing the results of the two thermometers.

Electrical hygrometers

Electrical hygrometers are humidity measuring devices – measure the electrical resistance of a substance, which actually is resistant to electric current depending on the level of humidity.

Humidity is determined by comparing temperature at condensation with air temperature.

digital hygrometer

A hygrometer can either indicate the relative humidity or the absolute humidity, as well as both. Simpler hygrometers will only tell you if the air is dry or damp. Hygrometers are commonly used for weather forecasting, in laboratories, storage areas, manufacturing plants and numerous other fields.

Nowadays, electric hygrometers are considered to be the most accurate tools of measuring humidity. They are simple to use and really convenient, so there is no reason why you should not try them, too.

Top 5 of Hygrometers for Home and Workplace Use

Mechanical hygrometers

There are many other kinds of hygrometers that use human hair to determine moisture content. They are commonly known as mechanical hygrometers, being based on organic substances contact.

The first hygrometer using human hair was built back in 1783, being invented by Swiss physicist and geologist, Horace Benedict. Nonetheless, this wasn’t the first hygrometer ever built. In fact, Leonardo da Vinci is the inventor who has built the first crude hygrometer in the world, back in the 1400s.

analog hygrometers

What is humidity?

To understand why a hygrometer can be extremely useful for anyone, you first need to know what humidity is. Humidity can be described as the amount of water vapor that exists in the atmosphere, caused by condensation and evaporation.

People commonly feel comfortable at a relative humidity between 35 and 65 percent.
For instance, humidity makes hot weather unbearable. This means that high humidity can make hot days even hotter. In the most extreme cases, high humidity can lead to exhaustion and even heat stroke.

hygrometers and humidity
What is humidity

Importance of hygrometers

Some facts about hygrometers:

  • A hygrometer will measure relative humidity.
  • This device needs some time to produce results, so it may take a couple of hours until delivering accurate information.
  • All hygrometers need to be calibrated before being first used.
  • For accurate results, you should place the hygrometer in the location in which you see the most visible signs of humidity.
  • Do not place your hygrometer near heat sources such as radiators, stoves, and heat registers.


Nowadays, electric hygrometers are considered to be the most accurate tools for measuring humidity. They are simple to use and really convenient, so there is no reason why you should not try them, too.