How Long Should You Run a Humidifier? [ 6 Factors To Consider]

If you live in an arid area or cold and dry climate, you will know how important a humidifier is to your life. It could be an effective way to relieve dry skin, sore throat, and congestion. It is also proven to be good for sleep. When running a humidifier, many of us don’t assure that how long a humidifier should be on?

In general, you can run a humidifier as long as the relative humidity level doesn’t exceed 55% or cause any adverse effect.

It will take a few hours or even a day for console humidifiers to reach the target humidity level, and then you can turn it off. Most models will run out of water within 6 to 36 hours.

The whole-house humidifier can run across the heating season, but the humidistat will regulate the humidity automatically so that you will see it run periodically during the day.

Many factors will affect how long you should run a humidifier and how often you should use a humidifier. Luckily, you can find every piece of information you should know at your fingertip by reading this post.

Let’s dive in!

Factors that decide how long to keep the humidifier on

The running time of a humidifier is determined by how long the appliance can run and other external factors. Therefore, I will analyze them one by one so that you can estimate the time more accurately.

Room humidity level

According to many sources, the ideal humidity level is between 30% to 55% for human beings. But various people have various preferences and needs. So you can set a target between these two numbers.

Some people feel great at a 35% humidity level, but others may still suffer from dehydrated mucous membrane or congestion. In this case, setting a 45% level would be a better choice for the latter.

On top of it, the gap between the room humidity level and your preset level is a critical factor in deciding how long to run the humidifier. 

For example, if the indoor humidity level is already at 35% and the ideal level for you is 40%, then the humidifier only needs to run for a short period since the gap is only 5%.

If the humidity level is already close to 50%, you should be very careful because many adverse effects will occur when the air is too damp.

The over humidified air can lead to condensation on windows and furniture. It can also boost the growth of mold, mildew, and dust mites.

Room temperature

As the temperature increases, the air can hold more water. It means that the relative humidity level will decrease accordingly, even if the total amount of water in your room’s air doesn’t change at all. 

Increasing the overall relative humidity in summer would be more complicated than in winter because the room temperature is higher, and you need to use more water to get the same increase.

So you should increase the output rate or extend the running time of your humidifier to achieve this goal.

Room size

Packaging often identifies the humidifier as being appropriate for a certain square footage of the room. It is easy to understand that the humidity increases more in a small room with the same humidifier than in a big room. 

Suppose you plan to move your humidifier to the living room from your bedroom. Then you should prepare that it will run longer to make your living room humid. 

You ought to get a proper one according to the foot square recommended on the product description so that the humidifier can humidify instead of over humidifying the room. 

Your health condition

Humidifiers can relieve many symptoms of conditions related to dry air. If you have a cold, you can use the humidifier constantly to alleviate congestion and parched throat. If you suffer from allergies, moistened air can settle out some allergens. 

In other words, you can leave the humidifier run longer when you are under the weather.

Use a humidifier with other devices

Some other devices can work with a humidifier together to get a better result.

You can use a humidifier and a fan at the same time since the fan can help disperse the moisture particles, so the humidity in other corners can be improved very soon.

You could also choose to use an air purifier and a humidifier together because the air purifier can refresh the stale air in the room and help relieve symptoms further.

How long can your humidifier run?

Sometimes, the device limits how long you will run the humidifier. Here are three main factors you should take into account.

Water tank capacity

Even though it is not always correct, in many cases, the larger the water reservoir, the longer the appliance can run. Many brands provide models that can hold up to 4 gallons of water, but some models can only hold 1 gallon of water. 

If you intend to increase the humidity of a large room, then a humidifier with a small tank can run out of water very soon before the preset level is reached. A model with a larger tank can continue to work for up to 36 hours at the same output rate.

The output rate of your humidifier

output rate of humidifier

The output rate decides how many moisture particles the humidifier can release per hour. There are a few settings for a humidifier to choose from. If you want to increase the humidity quickly, you should select the option with the maximum output rate.

It also means that a humidifier with a high output rate will need to be run in a shorter time than the one with a low output rate.

Types of humidifier 

Generally speaking, evaporative humidifiers have a better humidification performance than ultrasonic humidifiers. If you want to shorten the running time and get the result quickly, an evaporative unit could be a sensible option.

Should the humidifier run all night?

You don’t have to, but you can run a humidifier all night. Many models come with a sleeping mode with a lower output rate and less noise to sleep well in a comfortable environment without worrying about the air becoming too damp. 

Many parents also use it for their babies and children because it can help to relieve congestion and sore throat and let them recover more quickly.

So keeping your humidifier running for 8 to 12 hours at night is totally fine.

How often should you use a humidifier?

If you use a humidifier for your houseplants, using it for 3 to 5 hours per day is enough. If you live in an arid region, you can extend it up to 6 hours. 

For those who use a humidifier for family members, you can use it daily until the dry climate has gone. If the model has a built-in humidistat, then it may turn on and off a few times during the day. If you have to adjust it manually, you should change it according to the result of the hygrometer or your feelings.

Solutions to help you decide how long you should run the humidifier

If you still have no idea how long you should leave your humidifier on. Here are three ways that can help you out.

Use a hygrometer to monitor the humidity level

things to help you know how long should a humidifier be on

Although there are a few ways to identify the humidity without a hygrometer, a hygrometer is still a very affordable and straightforward way to go.

You can check the hygrometer a few times a day to see if you need to turn on or off the humidifier.

Observe the signs of high humidity

Sometimes, you just forget how long you have run your humidifier. In this case, you can observe if there is any sign of over humidifying even if you already have a hygrometer at hand.

When the air is too wet, the condensation will form on windows and furniture. If you see any condensation, you should turn the device off immediately as it will rot the furniture and let the mold set in.

Besides, when you feel the air is clammy, it is also a sign of high humidity.

Buy a humidifier with a built-in humidistat

Most whole-house humidifiers have a built-in humidistat so that you only need to adjust the settings at the beginning of winter and summer and you are all set. You don’t have to worry about how long you should leave the humidifier on anymore by using a humidistat.

Some advanced console humidifiers also have a built-in humidistat. But you should still remember to change out the water daily to prevent the reservoir from becoming a peri dish for mold and bacteria.


We have discussed how long you should run the humidifier in this post. Honestly, it is hard to give a clear-cut answer to this question, but the rule of thumb is that the humidity level in the room shouldn’t exceed 60%, cause any condensation, and make you feel uncomfortable. 

Many factors will affect the running time. The room temperature and room humidity are important external factors. Also, the output rate and tank size will limit how long the humidifier can run. 

If you want to get rid of worrying about the running time, then purchasing a one with a built-in humidistat is the ultimate solution. Otherwise, checking the hygrometer often will also help you control the humidity at home.

About The Author

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested dozens of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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