How Long Will A Dehumidifier Take To Lower Humidity?

A dehumidifier gets rid of excess moisture from your indoor air. If the summer is having the best of you, just get this appliance. You only need to consider the space rating.

But… how long does it take for a dehumidifier to work?

Usually, a dehumidifier can take up to 12 hours to lower the humidity to the desired level when it is new. However, when you have had it for some time, it can take much less, about 5 to 7 hours. Other factors include the humidity level, the size of the unit, and the size of the space. 

How does a dehumidifier work?

How Long Does It Take a Dehumidifier to Work

A dehumidifier removes excess moisture from your indoor air. It does this by taking in the moisture-laden air and blowing out dry air.

In the modern portable dehumidifier, damp air passes over the dehumidifier coils, where the moisture condenses and drips into the collection pan and eventually into the bucket.

The refrigerant dehumidifier-type that you can buy on is the most common. Such units come in all sizes, so you should definitely find a unit that will serve you appropriately.

Things that determine the performance of a dehumidifier

Many things will determine how well, or how badly, a dehumidifier performs. These factors also determine its running time.

Remember, a dehumidifier consumes low electricity, but if it runs longer than necessary, you will still have to foot an expense that you can do without.

These factors include the following:

  • The type of dehumidifier
  • The capacity of the appliance
  • The indoor humidity level
  • The size of the space that you are dehumidifying
  • The indoor temperature

Remember to close the doors and windows so that the unit can function efficiently. If you do not, you will be dehumidifying your indoor air and more moist air will be coming in through the open windows and doors.

1. The type of dehumidifier

One type or model of dehumidifier can take minutes to reduce the humidity level, while another one may take hours. There are a few factors determining this.

When you buy yours, find out how much water it can draw from the air in one hour. That should give you a good idea of how much work the appliance can do.

If you have a large space to dehumidify, buy a dehumidifier rated for that kind of space. For example, the Ivation dehumidifier which you can buy on is rated for 4500 square feet.

The most common types of dehumidification units include portable varieties, furnace dehumidifiers, and mini dehumidifiers. The portable varieties can also come in desicant, refrigerant, or other types.

2. The dehumidifier capacity

This means how much water the unit you are going to buy can extract in 24 hours.

Some units can remove up to 75 pints, while others can extract 50 pints or 25 pints. The high-capacity units extract more water in a given amount of time.

For example, to bring down humidity from 90 to 40% in a 50-square-foot room at 820F, a 50-pint unit will take 11 minutes, while a 22-pint one will take 34 minutes.

So, you can go for a higher-capacity dehumidifier so that you can save on energy costs. It will take less time to get rid of moisture.

The small dehumidifiers for grow tents would take too long to lower humidity in a big room. Such a unit would probably work too hard, such that it would end up overheating.

If you live in high humidity Florida, you need a big portable unit. Most probably, you need to get a dehumidifier with a drain hose so that it can dispose of the water continuously.

3. The indoor humidity level

It will take more time for a dehumidifier to work if you have high humidity inside.

If, for example, your home leaked, your unit would take more time to reduce the moisture levels. This is unlike when you have the typical summer humidity.

How long do I need to use a dehumidifier after a leak? You should use it for up to 48 hours. However, this will depend on factors such as the size of the area affected, the materials damaged, and the level of humidity in the area.

You should use a higher-capacity unit if you want to get rid of high levels of air moisture. If your premises are extremely damp, a unit that can remove 75 pints in 24 hours would be better than one that can do 25 pints.

A hygrometer tells the level of humidity, so buy one. That way, if the humidity level rises above 50%, you can switch on the dehumidifier.

Also note that consistent high humidity causes mold growth in your home. In return, this causes severe mold exposure symptoms.

4. The size of the room

The time it may take a dehumidifying unit to work in a 500-square-foot room is not the same as the time it will take in a 2000-square-foot room.

The larger the space, the longer the unit will need to work. When ordering a dehumidifier for a grow tent, for your bedroom, or for any other room, check the space rating.

Read the unit’s description to see the space the dehumidifier is rated for. Also, do not buy a unit that is too big for a room. In the post on why the Midea dehumidifier keeps going off, we said that if it is too big for the room, it will work briefly and then go off.

The average bedroom size in the USA is 132 square feet. Therefore, to achieve the best humidity level for the bedroom, get a dehumidifier rated for 200 to 250 square feet.

5. Indoor temperature

When the temperature is high, the level of humidity is high. The reason is that when the air is warm, it expands. Therefore, it holds more moisture.

That is why humidity is high in Seattle in the summer, and a dehumidifier would need to run longer to control the humidity level.

There is a direct relationship between humidity and temperature. In the winter, most people need a humidifier. In summer, they need a dehumidifier.

Overall, whether it is winter or summer, the humidity level in the room should be 30 to 50%. If it goes higher than that, black mold starts to grow in the house. In fact, mold grows in warm and damp places.

The recommended temperature for your indoor space is 65 degrees Fahrenheit (18 degrees Celsius).

How quickly should a dehumidifier fill up?

The condensed moisture collected ends up in the dehumidifier bucket or drip pan. This will fill up as more moisture is extracted.

It will need emptying. Some models have a drainpipe, so they don’t need emptying. You could also get a dehumidifier with an internal pump, which is very good for disposing of the water over a vertical height.

The time it will take for a dehumidifier to fill up will depend on:

  • The size of the tank: the larger the container, the longer it takes to fill up
  • Humidity levels: When the air moisture is high, the dehumidifier will fill up more quickly
  • Dehumidifier capacity: A 75-pint unit will fill up faster than 25-pint one

If you have just started, it may fill up in about six hours. Again, this depends on the tank, the humidity level, and the capacity of the unit.

The good thing is that even when you are not at home, the dehumidifier will stop when the bucket is full of water.

How do I know if my dehumidifier is working?

A unit that is working needs to get rid of the excess moisture to bring the level of relative humidity down. Therefore, looking at the hygrometer should tell you whether the humidity level has gone down.

You will know that your appliance is working when:

  • The relative humidity level starts to go down
  • The water tank fills up
  • The dry and warm air is coming out

If a dehumidifier blows cold air, it is most probably not drawing moisture out of the air. To know whether your unit is working, just place your hand against the grille. If the air is cold, the fan is running, but the unit is not removing moisture from the air.

Also, if the dehumidifier is blowing hot air, it could mean it is working too hard, so perhaps it is too small for the job. It should only blow warm air.

When to run the dehumidifier

You may be wondering when to use the dehumidifier, for how long, and whether you can run it constantly.

When to run the unit depends on several factors. These include:

  • The level of humidity
  • The size of the room
  • The capacity of the unit

We have already explained these factors before, so we will not go back to them again.

When the humidity is too high, you may need to run the dehumidifier 24 hours a day. However, if the levels are low, you can run it at a given time, let’s say in the morning or evening.

For a large room, you should run the unit throughout the day. The reason for that is that the unit needs more time to remove moisture in a larger place than in a smaller one.

Remember, the more you keep the unit running, the more energy costs you incur. Therefore, if you want to save on energy costs, you should run it when necessary.

If you do not know how long you should let your unit run, just enter the correct humidity settings. Most portable units come with built-in humidistats. Thus, when the humidity rises, it switches on automatically, and vice versa.

Is it safe to run a dehumidifier constantly all the time?

You can run a dehumidifier for 24 hours continuously, and no problem will occur. The reason for this is because the unit will switch off automatically when:

  • The bucket gets full
  • The set humidity level has been reached
  • Some will even switch off to prevent damage from overheating

If your dehumidifier is working correctly, it will not lower the humidity level below what you have set. The recommended indoor humidity level is 30 to 50%.

Therefore, if the hygrometer shows the humidity level within this range, there is no need to run your dehumidifier for many hours.

If you are using a dehumidifier for drying clothes, you will need to run it as long as necessary, or at least until the clothes are dry.

If you are using a dehumidifier to dry a room, again, you will have to run it as long as necessary. The best thing is to get a dehumidifier that comes with all the bells and whistles—a drain hose and humidistat. Once you attach the drain pipe, the unit can practically run itself.

Is a dehumidifier safe?

You want to leave your dehumidifier running all day and night, and you are wondering: is it safe? Luckily, dehumidifiers are almost harmless.

However, because of its constant contact with water, mold can develop inside the unit easily. Therefore, you have to clean the dehumidifier bucket at least once a week.

There are also issues that may arise from poor placement of the dehumidifier, overheating, and others. To run it safely and constantly, your unit should:

Be able to turn off automatically: Most units have an automatic turn-off function such that they go to “sleep mode” once the indoor air reaches the required level of humidity or when the tank is full.

Have a tilt safety feature: If the unit topples over or tilts, the function stops the unit from operating to prevent damage.

Overheating protection feature: A dehumidifier uses a motor that can overheat because of constant use. The feature enables the unit to turn off when the motor is overheated and turn on when it cools off.

Place the unit correctly: Don’t place the dehumidifier on the floor. It should be a foot or higher from the floor. Also, place it in a place where it has enough airflow. Keep it at least a foot from walls or furniture.


Buy a good dehumidifier, one that has all the important functions, so that it can practically run itself when you are traveling.

If you live in a place with high humidity, investing in a dehumidifier is paramount. If you have runaway humidity levels in the house, you will have mold, damaged electronics, books, paintings, and other problems.

For the safety of your household items, keep the humidity level between 30 and 50%, always!