Seventy percent of the surface of the planet is covered in it and the majority of the human body is made out of it – water is all around us. Quite literally too, as moisture in the form of humidity is in the air you breath. The level of humidity, measured in percentage points, can have resounding effects on your home, business, and even your health. This is where the hygrometer steps in – by the end of this guide you’ll know everything you need to get the one that is right for you.
What is Hygrometer?
A hygrometers job is simple: These devices measure the amount of water vapor in the surrounding air. Coming in a variety forms, a hygrometer can do this by either using electricity, chemicals, thermometers or rely on mechanical ways. Often times these devices can measure other things such as temperature. This is especially important because the higher the temperature the more water vapor can be held in the air
Other types of hygrometers can be used to measure soil, but more often than not these devices are usually reserved for some sort of controlled space. Hygrometers can be found in everything from greenhouses, industrial areas, and humidors, while also being located in other climate areas like cellars or museums. In residential areas, hygrometers can be used to see if your home is more susceptible to mold growth, or needs the inclusion of either a dehumidifier or humidifier.
Types of Hygrometers
Hygrometers come in many different forms, shapes, and mechanisms of use. Knowing the difference between all these types will help you better purchase one that works best for you.
Resistive models of hygrometers use a piece of ceramic that is exposed to the
air. When more water vapor condenses on this piece of ceramic the electrical
resistance is increased, indicating the humidity is higher. Capacitive models,
on the other hand, use a pair of metal plates. The more moisture in the air
affects the amount of static charge between the two plates.
Using a pair of thermometers to measure, this type of hygrometer has one dry
and one wet bulb. When evaporation occurs in the wet bulb the temperature drops
– the difference in temperature between the two determines the level of
humidity in the air. This type of hygrometer works best in either storage containers
that need dry conditions or for outdoors.
- Humidity Cards:
Probably the simplest way to measure humidity and can be considered a primitive
type of hygrometer. These cards are embedded with a cobalt chlorine solution
along with other chemicals. When moisture levels change in the surrounding air
these spots will change color. Humidity cards can accurately measure anywhere
from 5 to 95 percent of the relative humidity.
Similar to a mechanical clock or pocket watch, these devices are also called
analog hygrometers. One of the oldest hygrometers, these devices require
periodic upkeep and testing to make sure they are working correctly. Can
measure humidity with a margin of error ranging from 1 to 3 percent. While they
can work outside they are usually recommended for indoor use.
This fairly inexpensive device uses a simple piece of either nylon, cellulose,
or even hair to measure moisture in the air. These fibers wind around needles,
gauges, and dials – when they expand or contract these pieces are activated.
Great for indoor and other controlled environments such as terrariums or
Also called a dew-point hygrometer, these devices are considered some of the
most precise and are often used for scientific research. Working on similar
principles of a foggy mirror after a hot shower, the small chilled mirror
absorbs the moisture in the air. Light is then scattered by the water droplets
or frost, stopping the cooling process. This type of hygrometer can also
measure things like carbon dioxide.
- Gravimetric: Another high accuracy yet an expensive option, this hygrometer is also used in many scientific studies. Using a small bit of the surrounding air and comparing it to an equal amount of controlled dry air makes these tools probably the most accurate. Often used to calibrate other types of hygrometers because of their difficulty of use.
Hygrometer vs Hydrometer
A hygrometers job, as mentioned before, is to measure the relative moisture in the air using a variety of ways. A hydrometer is often confused for a hygrometer because of the name similarity but they actually have differing jobs. A hydrometer is built to measure the density of a liquid. As imagined a hydrometer is often used in more scientific pursuits as this isn’t really useful for most residential purposes.
Even the shape of hydrometers is much different from hygrometers. Whereas a hygrometer is typically shaped in either a flat square or circle with a potential additional sensor, a hydrometer is a long glass tube that expands on the bottom that rests inside a cylinder. Most hygrometers are not waterproof, whereas a hydrometer is actually submerged into the water until the stem touches the liquid.
Top 10 Best Hygrometer Reviews of 2019
Picking a hygrometer that is great for you can be a bit of an overwhelming process with the myriad of devices out there nowadays. To help you with this process here is a list of hygrometers, each one bringing something new and unique to the table.
1. Best Digital Hygrometer: Thermopro TP55 Digital Hygrometer with Jumbo Touchscreen
The large LCD display comes in at 4 inches in height and is touch screen compatible, making this Thermopro hygrometer one of the best digital models on the market today. Accurate and highly responsive readings are made for humidity and temperature – indicating highs and lows, current levels, and the ability to easily switch between Fahrenheit and Celsius. Also incorporated are trends which give you the ability to react accordingly and adjust your thermostat.
Built into this machine are multiple mounting designs letting it work on your wall, tabletop, or via magnet. Included with this device is a pair of AAA batteries, letting you start up this hygrometer right out of the box. The manufacturer thought far enough ahead to include a backlight, allowing you to use it in dark conditions – don’t worry though because this light turns off after fifteen seconds ensuring it won’t keep you awake.
Everything considered this machine proves that affordability doesn’t mean low quality. Outfitted with all of the necessary features means you won’t be disappointed with this hygrometer.
2. Best Overall: Ideal Sciences Wireless Temperature & Humidity Sensor
Want a state-of-the-art machine that has all the bells and whistles? Then look no further than this Ideal Sciences device, which is overall the best hygrometer. Measuring humidity and temperature have never been easier with this machine as it uses wifi to allow you to remotely monitor all the essentials from any of your smart devices. Text and email alerts can also be automatically pinged to your phone.
This machine has a huge range it can measure – temperature tracking anywhere from -40F to 125F and humidity from 0 to 100%. Even when the system monitors can be customized based on too – with 5, 10, 15, 30 or 60-minute readings available. This machine is powered by a pair of AA batteries which are included.
Updates via your smart devices give a slew of data, with multiple numbers in tables, easy to read graphs, and many other features. Great for using inside of your home or at a business, this small hygrometer merely attaches to the wall or room of your choice.
3. Best Hygrometer for Home use: Ambient Weather WS-10 Indoor/Outdoor Hygrometer
Simple to read hub with not one, not two, but three remote sensors makes this Ambient Weather product the best home hygrometer right now. Ambient Weather is known for making a slew of highly advanced, yet inexpensive devices that give accurate measurements every time and this machine is no different. The uncomplicated display gives a slew of data easily understandable even at a glance.
For those that want even more accurate data, additional sensors can be purchased, allowing you to connect upwards of eight to this device. The console itself has three buttons on the bottom of it allowing you to set alarms to go off when the maximum or minimum humidity or temperature has been triggered. On the display, you’ll be able to see everything related to temperature and humidity including minimum and maximum within a certain time frame.
The sensors themselves are small and can be put anywhere from inside the home to anywhere outside and are capable of measuring accuracy between -40F and 140F along with 10% to 99% of humidity.
4. Best Humidor Hygrometer: Cigar Oasis Caliber Digital/Analog Hygrometer
A no-nonsense device that does everything you need when it comes to measuring the humidity of a given area. Being one of the best humidors means that you have both digital and analog capabilities on this machine. The analog portion is color coated – high and low extremes are red, with middle labeled yellow, and the ideal range in green. The accuracy is around 1% in either direction, with recalibration possible on the rare chance the readings get out of whack.
This small little hygrometer is easily mountable via a secure magnetic piece, while also having the capabilities to read the temperature as well. This temperature setting is switchable between Celsius and Fahrenheit – impressive amount of features considering it only has a diameter of 2.25” and a depth of 0.7”! Because of its tiny size, this hygrometer works great in calculating the humidity of the smaller area, while also being accurate in larger ones as well.
A combination of high accuracy and simple analog exterior makes this a stellar pick for just about anyone.
5. Best Runner-up: SensorPush Wireless Hygrometer Smart Sensor
Looking for a highly advanced hygrometer but you don’t want to break the bank? Then take a gander at the best runner-up model. The combination of super-accuracy mixed with 21st-century technology gives you the ability to keep track of all your home or business vitals via your smartphone. Know everything from temperature and humidity, with multiple sensors giving you multiple readings for different rooms.
The app used with this machine is beautifully made and is compatible with both Apple and IOS products. Multiple types of graphs are viewable as well – simple line graphs, box and whisker graphs, or just a cursory glance at the raw numbers. You’ll get the most accurate numbers too as the sensor has a temperature range from a frigid -40F to upwards of 140F, with a humidity range from 0 to 100%.
Capable of measuring both inside and out with over 300-foot range means that just a few sensors can cover most of your home. Keep track of dry and moist ranges and ensure your family is kept comfortable and safe with this SensorPush hygrometer.
6. Best Indoor Outdoor Hygrometer: AcuRite 01083 Pro Accuracy Temperature & Humidity Monitor
Timeless design means fast and accurate readings on your part. Because it is capable of calculating a wide range this is the best indoor/outdoor model you can find. Despite its cheap price, the sensors can give accurate readings upwards of 158F – which is even higher than more advanced models. You’ll know all of these lows and highs for the past 24 hours too, as they are easily viewed on the left side of the screen.
Accuracy is professional level – temperature being accurate within a half of degree and humidity within 2%. If you notice that the readings are starting to get slightly off you have the opportunity to manually calibrate it. These measurements are taken every 10 seconds, so you know you’re getting a play by play.
There are multiple mountable capabilities in this machine – wall and magnet mounted options available or just set it up as a tabletop device. The screen itself can be glanced at from a distance to give you all the information you need via the color coated humidity line, with large numbers to go along with it.
7. Extech 445815 Humidity Meter with Alarm and Remote
This Extech device comes embedded with everything you’ll want in a hygrometer. This display itself uses jumbo size numbers and lettering, making it a great choice for those that are sight impaired. Just the smallest cursory glance will give you the humidity, temperature, and DEW point. On the side are a pair of adjustment disks – letting you set an alarm with just a simple push up or down.
Put this hygrometer anywhere you need to go with the built-in kickstand or use the included bracket to mount it to the wall. The sensor itself is found on the upper left portion of the hub and can extend 18 inches, allowing you to peak around or into areas you couldn’t normally go. Get accurate measurements too with ranges from 14F to 140F and humidity from 10% to 99%. A straightforward machine that does its job and nothing more. The streamlined design makes it small enough to put just about anywhere while having a large enough screen to be viewed even across the room.
8. Cigar Oasis Caliber IV Digital Hygrometer
The bar-like design of this machine and the magnet mount means you can put this tiny hygrometer wherever you need it. Don’t let the simple design confuse you though, as a Cigar Oasis device this one is highly accurate – this one being within just a single percent of humidity either way. You can also get a reading on averages for the past 3 days along with highs and lows for both humidity and temperature.
This Caliber IV hygrometer is less than 4 inches in diameter and needs only a single CR2 battery to keep it powered for a long time – which is included. Over the course of its life, there is the small chance that it won’t be as accurate as when you took it out of the box. Don’t worry, as Cigar Oasis has thought of this contingency and allows for manual calibration if you need it.
The slim profile of this machine means you can stick it on things like a refrigerator or anything metal if you want to.
9. HygroSet II Round Digital Hygrometer for Humidors
A unique design for a unique hygrometer! Capable of giving you accuracy between a couple of percent from anywhere as low as 20 to 90 means you can be sure you’re getting a solid reading when you need. The temperature is even more accurate, being within plus or minus a single degree Fahrenheit. You’ll get only the most up-to-date reporting too with the measly 10-second refresh rate.
This HygroSet device is the second iteration of this model and comes with a simple to read digital display. Great for cigar humidors and many other areas, this device attaches with double-sided tape. There is a little dial on the front for easy calibration making sure you can keep this device accurate for a long time coming. At only 1.75 inches in diameter, you’ll be able to set this in a sport where it won’t look bad.
Temperature can be set at either Celsius or Fahrenheit, with an accurate range of 0 to 50C or 32 to 120F.
10. La Crosse Technology WT-137U Digital Hygrometer
La Cross is an excellent company and they’ve brought their eye for quality with this hygrometer. The snazzy double framed design didn’t crowd out the digital screen either. Large numbers for both temperature and humidity can be seen, while an analog graph for the humidity itself gives the range from dry, comfortable, and wet. For easier understanding, this graph is color coated with red in either extreme and green in the center.
The keyhole-like bracket on the back end lets you hang this device from the wall – or merely have it on a table with the stand! To get everything powered all you need is a single AAA battery. With just that 1 battery you’ll get a good reading of relative humidity ranging from 20% to 95%. Coming in at 3.5 inches squared and weighing less than an ounce means that moving this device around is super easy.
What to Know Before Purchase
If you’re looking to peruse through all the different hygrometers yourself then you should keep an eye out on a few different features. While each device is unique there are some characteristics you should nonetheless keep in mind.
- Functions: Hygrometers are often multipurpose devices that can do quite a few things – the most basic is reading the temperature. Even this basic feature can include additional functions like minimum and maximum, with most models allowing you to set some sort of alarm.
- Design: This isn’t just how the hygrometer looks – though that is an important factor – but also how the overall design of it coordinates with its functionality. Whether it has buttons, switches, and knobs and where they are located. You need to know whether or not you need a streamlined little device or something more ornate, like a digital screen in a frame.
- Mounting: Where are you going to put your hygrometer? Because if you don’t have the right mounting options then even a good one is useless to you. Most larger models come with some sort of stand to put on a table or nightstand, where others have a bracket so you can hang it up. Mounting doesn’t just have to just be a screw either, as many smaller models use magnets or tape to stay where they need to.
- Accuracy: Those numbers related to humidity and temperature don’t mean much if they aren’t accurate. Needless to say, more expensive models are typically more accurate, with these models usually within a plus or minus percentage point. The average for the market seems to hover more closely to around 3% though. The most accurate hygrometers are those certified by NIST.
- Battery & Power: While having one of these devices powered by AC power isn’t unheard of, batteries are what they usually rely on – with combinations of AAA and AA the most common but far from the only types.
- Monitoring & Alerts: Briefly mentioned before, alerts refer to a setting that activates the hygrometer to signal that the humidity is too low or too high in the area. More advanced models are capable of sending information directly to your smartphone either via text or email. This is important if you or people in your household are sensitive to high or low moisture.
- Sensors: This is the little part of the device that actually does all of the work of collecting the data. Many smaller models have the sensor built into the device, while others use a remote sensor that can attach to different areas and beam the data to the hub. There are even some models that use multiple sensors, inside and outside, to give you the capabilities of seeing multiple data points at once.
Frequently Asked Questions
While hygrometers functions are easy to understand, you probably have a few questions about them – this is perfectly normal! Here are a few of the most common questions we have come across.
How do I set up my hygrometer?
Installation of a hygrometer is pretty straightforward and really can’t be considered installation at all. Merely slap the batteries into the back – your model may or may not come with them – and then find an area to put it. If you are going to hang it up make sure to keep your variants mounting capabilities in mind. If you have a more advanced model make sure to download the associated app to your phone or smart device.
Setting the alarm can vary, but usually involves pushing down the button or switch labeled “ALARM”. From here you’ll need to set at the point you want it to go off with the “MIN/MAX” button(s).
What level should my home’s humidity be at?
It can vary depending on what you are used to and your environment, but many people seem to be most comfortable anywhere from 30 to 50% relative humidity. High humidity can not only make the weather feel either warmer or colder than it actually is but also creates a range of health problems throughout your home such as mold growth and breathing problems. Anyone who has walked into a bathroom after a shower can speak for how uncomfortable it can be too!
Too low humidity can be a problem too though, as dry air can become a breeding ground for viruses and bacteria. To make matters worse dry air can actually put stress on the lungs, causing coughing fits that just spread more bacteria around. While keeping humidity levels at an average of around 40% is ideal, keep in mind that warm air can hold more moisture than cold air, making winter often feel dryer than summer.
Where is the best place to put my hygrometer?
Depends on what you are using your hygrometer for. If you just want it for general use then put it in a highly used room like the living room, which should give you a decent cross-section of the relative humidity levels of the entire area. If you have a cellar or some sort of humidor, then putting the hygrometer in there is a no brainer.
If you want to keep track of multiple areas then rather than putting multiple hygrometers spaced throughout your area think about investing in one device with multiple sensors. Not only will this save you money but will ultimately be much more organized and look better.
How can I adjust my humidity?
Air conditioners already take a certain amount of moisture out of the air but far from all of it – nor would that be even desirable. If you find your home still feels too damp, then machines call dehumidifiers to exist for this exact job. These machines come in a variety of sizes, so make sure you get one that is up for the job for your area. You will need to change the filters and dump out the moisture it collects from time to time as well.
On the reverse end, too little moisture can also create its own issues and that’s where the humidifier comes in. Typically needing a small tank of water that needs to be periodically filled or attached to some sort of sink area, these devices suck in air and add moisture to the air.
What is NIST certification?
The National Institute of Standards and Technology (NIST) is a non-regulatory agency that keeps track of all scientific device measurements tools to make sure they are up to snuff. There are multiple ways of doing this, with the ultimate goal to ensure measurement devices are uniform to ensure accuracy.
NIST certification is only given to devices that have gone through this process of careful calibration. While hygrometers often have a certain margin of error in all of them, a NIST certification ensures that this variance is kept at a minimum and that the machine in question should give accurate results if everything is in working order.
Picking a good hygrometer is just knowing what you need to get out of it. There is a range of ways these devices work with electrical being the most commonly found today. Coming in digital and analog, wifi capable or more streamlined, there is plenty for you to choose from. Getting a hygrometer that is NIST certified will ensure you’re getting a machine of impeccable quality with any of the ones in this guide more than up to the job.