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Tips for Using and Choosing a Hygrometer

Updated on September 27, 2011

Monitoring Humidity With a Hygrometer

If you need the ability to monitor the relative humidity in your home a hygrometer can help. Whether you want to assure a humidifier or dehumidifier is doing it's job or you want to protect valuables or loved ones, they can alert you to problems.

On this page you can learn a bit more about these devices. You can find more information about why measuring and controlling the relative humidity in your home is important, get some tips on choosing a good hygrometer, and see a few models that other consumers have recommended.

About These Devices

There are different kinds of hygrometers, but they all have the same purpose. To measure the humidity in the air. For most of us, we want to measure humidity in order to alert us to either a lack of moisture or excessive moisture in our home. Certainly maintaining an ideal humidity level is important for our health and the safety of our home and belongings.

Too much moisture can encourage the growth of mold, mildew, fungus, dust mites, and so forth. These are particularly problematic for those with allergies but can have serious health consequences for everyone. Having an environment that is too dry can also be problematic. Wood can of course be effected but certainly, drying effects our skin, respiratory tract, and so forth.

In our home, a relative humidity level of 30% to 50% is considered ideal. Above 55%, the risk of mold growth is significantly increased.

Hygrometers allow you to monitor humidity, and in some cases, temperature, and dew point. (Dew point is the point at which condensation may occur.)

For one of these devices to work properly it must be calibrated. This is a relatively simple task which you can find described here. It's wise to check and recalibrate them periodically, at least once per year. It's also important to keep in mind that the humidity within your home will vary from spot to spot. For instance, if you measure humidity near the center of the room, it may be different near the wall. There is more information about types of hygrometers and recalibration included in the links at the bottom of this page.

For some people, measuring the humidity in a few choice locations suits their purpose. Perhaps they need to monitor a location where they store guitars or violins. Perhaps they need to monitor a storage closet in the basement or the baby's nursery. Small hygrometers can be mounted on a wall or set on a shelf or desk top to do this monitoring. Most of them are quite small and unobtrusive as well as affordable.

Buying Tips

As mentioned above, there are different types of hygrometers, but for the sake of the average consumer, choosing between an analog and digital hygrometer is the first step. Analog devices are sometimes preferred for their simplicity or design characteristics. Digital models are easier to read accurately. Of course you'll also want to assure that the model you choose is intended for the environment where you'll want to use it. An outdoor model will need to tolerate the more rugged conditions and be able to monitor a wider range of temperatures and humidity levels.

Of course a primary consideration when choosing a hygrometer will be it's accuracy. Manufacturers will indicate accuracy in the literature. For instance, a device that indicates it measures relative humidity between 1 and 90% within +/- 2% will be more accurate than one that measures relative humiditiy between 1 and 90% within +/-5%.

However, buyers need to be aware that they should always check/test their hygrometer and re-calibrate as necessary in order for it to be accurate. It should be checked periodically over it's lifetime as indicated above.

If a consumer wants to be able to monitor relative humidity or temperature remotely, then they will need a device that comes with a sensor. These can require that a cable or wire be run. Sensors with a cable connection will tend to be more accurate. However, wireless models are available and certainly are more convenient as far as installation.

When a wireless sensor is used, buyers should check to be sure of the distance at which it will operate.

For those who want to also be able to spot check humidity, a probe or digital pyschometer is useful.

Another handy feature on any hygrometer is it's ability to store information about minimum and maximum read outs for a given period of time, a day for instance. This means that a user can know the extremes, even if those extremes occur while they are gone or not checking the read out. Some of these units will also include an alarm or an alert that signals when a set level is exceeded. For instance, if a user wants an alert when humidity exceeds 60%, some devices can flash a warning or begin beeping.


This Extech hygrometer measures 3.9" W x 4.2" H x .78" L and can be hung on the wall with the included bracket or stood on a desk top with the built-in stand. The LCD display shows relative humidity, temperature, and dew point. It records relative humidity from 10 to 99% accurately within +/- 4% and temperatures from 14 to 140 degrees F within +/-1.8 degrees.

It also features a remote probe which extends 18" and can be used for measuring behind walls. It has a programmable alarm which can be set to give off a visual or audible alert when a high or low humidity level is exceeded. It will also recall maximum and minimum readings for you to monitor what is occurring while you're not present.

This device operate off of 2 AAA batteries.

A Closer Look at the Extech Hygrometer and Thermometer


This hygrometer from Honeywell features an easy to read LCD display with 1" numbers and high contrast. The main unit measures 4.33" W x 4.86" H x 1.08" D and can rest on a desk top or be hung on the wall. The main unit will display both temperature and humidity data for indoor or outdoor locations. It has a wireless sensor that can transmit data remotely, from as far away as 100 feet.

It senses and displays temperatures from 23 to 122 degrees F indoors and from -38 to 158 degrees F when using Lithium batteries or -4 to 158 degrees when using alkaline batteries. It displays humidity levels from 25 to 90%. The main unit requires 2 AA batteries and the remote sensor two additional AA batteries. This device is capable of monitoring up to 3 remote locations but this requires the purchase of two additional sensors. This device is able to recall minimum and maximum recorded data and comes with a one year warranty.

A Closer Look at the Honeywell TM005X Hygrometer and Thermometer

Analog Models

Western Digital offers this very affordable, small 2.5" diameter device. It requires no batteries to operate and can be re-calibrated with a small calibration screw. It has a magnetic mount.

The second item, from Chaney Instruments, is a 15" quartz clock with resin/wicker frame and flat glass lens. This indoor/outdoor clock includes a small hygrometer for measuring humidity at it's location.


This digital indoor hygrometer displays the current temperature and relative humidity in large, easy to read numbers. The unit measures 2.5" x 3" and can be set on a shelf or desk top with the fold out stand or stuck on a metal cabinet with the magnetic backing.

In addition to current readings, it also displays the daily high and low temperature and humidity readings. It operates off of 1 AA battery.

HygroSet II

This compact unit measures only 1.5"-2" across and operates off of a button cell battery. It displays both temperature and humidity. Values are refreshed every 10 seconds. The accuracy of humidity ratings is reported to be +/-2% at 65-75% humidity and temperature accuracy is reported to be +/-1 degree.

The unit can display either Celsius or Fahrenheit. It has a stick on magnet for mounting. A separate calibration kit can be purchased if desired.

P3 International P0270

This small device acts as a dew point monitor, thermometer, and hygrometer. It measures temperatures from 14 to 140 degrees (in either Fahrenheit or Celsius) with an accuracy of +/- 1% and relative humidity from 1 to 99% with an accuracy of +/- 3%. This information is then used to calculate the dew point. If dew point is 65% or greater, a visual/auditory alarm is triggered due to the potential problem of mold growth.

This device will store minimum and maximum levels and is easily reset. It measures 2.5" x 3.75" x 3.75" and operates off of 2 AA batteries.


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    • irenemaria profile image

      irenemaria 7 years ago from Sweden

      I absolutely agree. In the quite dry apartments we are living in, we need to keep track and add some water.