How Long To Wait for a Dehumidifier to Reduce Moisture?

Josh Mitchell

Written By

Josh Mitchell

Expert Reviewed By

Holly Curell

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I’ve worked with homeowners dealing with extreme humidity issues and the question I always get asked is ‘How long will it take for my dehumidifier to work?’.

Everyone wants to resolve the issue as quickly as possible but the truth is that there are a lot of different factors which can impact how long it takes for a dehumidifier to have an impact.

But don’t worry, because in this guide, I will help explain how long a dehumidifier should take to work, and how to get the best results while also prioritizing efficiency to keep your energy costs low.

Key Takeaways

  • It takes an average of about 10-12 hours for your dehumidifier to remove moisture to your desired levels when you first turn it on.
  • The exact time it takes depends upon how powerful the unit is, the size of the coverage area as well as the initial ambient humidity.
  • Humidifier placement as well as ventilation also impact the times it takes to dehumidify. Incorrect placement and open windows will increase the time it takes to dehumidify.

How Long Does It Take For A Dehumidifier To Work?

One thing I love about modern dehumidifiers is how simple they are to use.

how long does it take for a dehumidifier to work

A brand-new device will only take a few minutes to start up once configured, and your dehumidifier will start working to lower the relative humidity in the room from the second you switch it on.

However, it can take a long time to reach the desired humidity in your home.

Generally, the ideal humidity level is 30-60%. I aim for around 35% in my living room, but anything below 50% is the most comfortable for humans and maintains healthy indoor air quality.

The time it takes for your dehumidifier to reach this indoor humidity level can vary massively.

There are several factors that impact how long a dehumidifier takes to reach the desired level of humidity, but essentially it comes down to how much moisture there is in the room, and the capacity of the dehumidifier to remove it.

If you have an area with a relative humidity level of 85% and you want to reduce it to 45% then it will take longer than reducing it from 65% to 45%.

Similarly, if you have a larger dehumidifier with a greater capacity, then it will extract humidity more efficiently and reach the ideal conditions faster.


The first time you run a dehumidifier, it takes an average of 10-12 hours to reach the desired humidity.

This is because there are usually higher humidity levels when you start using it.

After this point, it shouldn’t have to run for as long to reduce the humidity as you should be using the appliance to maintain a relatively constant humidity level.

If it’s taking considerably longer than 12 hours to reach the ideal humidity, or your device isn’t reaching the desired level at all, then I would recommend looking into other solutions.

TL;DR: It can take up to 12 hours for a dehumidifier to work depending upon the initial conditions and how powerful it is.

dehumidifier settings

Factors That Affect How Long A Dehumidifier Work

There is no standard amount of time that your dehumidifier will have to run to remove the moist air from a room.

Sometimes I have to run my dehumidifier for just a few hours, and at other times I have to leave it running for days.

It all comes down to several key factors which will vary from home to home:

Humidity Level And Desired Humidity Level

When I talk about a dehumidifier ‘working’ I mean how long it takes to complete its task.

For a dehumidifier that means how long it takes to reduce the humidity from what it is currently, to what you desire it to be.

You’re completely in control of those humidity settings but it’s recommended that it remains between 30-60%.

The lower you want the humidity to be, the longer it will take to run.

Naturally, the more humidity there is in the room, the longer it will take for the dehumidifier to work to reduce it.

A dehumidifier in a damp room will take significantly longer to run than the same dehumidifier in a dry room.

I would recommend investing in a hygrometer or humidistat to know how much moisture is in the air currently so you have a better idea of how long to leave your dehumidifier running.

TL;DR: The initial humidity levels in your room and the humidity levels you want the moisture to drop to is one of the factor that determines how long it will take for your humidifier to work.

Dehumidifier Capacity - Defines How Powerful It Is

The capacity of a dehumidifier is basically how powerful it is, and how much excess moisture it can draw from the air.

Most household dehumidifiers have a capacity of between 20 and 70 liters, which indicates the amount of liquid water it can remove from humid air in a 24-hour period.

A high-capacity dehumidifier will work faster than a lower-capacity dehumidifier because it can extract the excess moisture in the air more quickly.

For example, in a small 50 sq ft. room that is completely sealed, it would take a 35-pint dehumidifier 18 minutes to reduce the humidity from 90% to 40%.

In the same room with the same conditions, it would take a 50-pint dehumidifier just 12 minutes to reduce the humidity from 90% to 40%.

It’s worth noting that the capacity level also impacts how quickly the dehumidifier’s water tank will fill up and need to be emptied, though larger capacity models tend to have bigger tanks.

what size dehumidifier do you need

TL;DR: The higher the dehumidification capacity of the unit, the faster it will remove moisture. This is measured in Pints Per Day (PPD).

Room Size - Larger The Room, The More Powerful Dehumidifier You Need

A dehumidifier’s size is based on its capacity, and not necessarily the size of the room.

However, the larger the space the more humidity there will likely be to deal with and small dehumidifiers lose effectiveness in very big spaces.

A dehumidifier will take longer to work in a big room as there is more moisture to deal with.

It’s important to measure the space and buy the right-sized model so that it can extract moisture from the air as quickly as possible.

Below is a rough guide, but in more humid conditions you will need a dehumidifier with a larger capacity:

  • A small room (300sq. ft) will need a 20-30 pint capacity dehumidifier
  • A medium room (500sq. ft) will need a 30-40 pint capacity dehumidifier
  • A large room (800sq. ft) will need a 40-50 pint capacity dehumidifier
  • A very large room (1200 sq. ft) will need 50 + pint capacity dehumidifier

TL;DR: The larger the room the more time it will take for a given unit to dehumidify.

Sources Of Moisture and How Severe They Are

Dehumidifiers are designed to deal with humidity, but the more sources of moisture there are in the space, the longer the dehumidifier will need to run to deal with it.

This is because there’s water entering the air and raising the humidity while the dehumidifier works against it.

The moisture levels in the room, and how much humidity is created, can be influenced by the design of the space, or by other factors.

Below are the most common issues which impact the humidity and how long residential dehumidifiers have to work for.

I would recommend fixing these so your dehumidifier takes less time to work.

  • Poor ventilation – the less warm air can circulate through the space, the more humidity will gather so your dehumidifier will need to work for longer.
  • Leaky pipes, showers, toilet tanks, or cracks in walls or windows can all let moisture in. This will mean your dehumidifier has to work harder.
  • Damp conditions or rainwater can cause humidity in your home which your dehumidifier has to work harder to remove.
  • Increased condensation as warm, wet air comes into contact with cold surfaces can mean your dehumidifier has to run for longer.

TL;DR: The more sources of moisture there are, the longer it will take for the unit to dehumidify. You may need very powerful unit if the sources of moisture are severe. 

Dehumidifier Placement is Crucial

If your dehumidifier isn’t placed properly then it will take longer to work.

I’ve seen countless homeowners place their dehumidifiers in the wrong position and it really impacts how much moisture the appliance can remove from the air.

Try to position your dehumidifier close to the damp areas and with space around it for air to flow.

I keep mine near the center of the room so there’s less risk of curtains or furniture impacting the airflow.

It’s also useful to place your dehumidifier higher in your home to capture the hot, humid air which naturally rises.


Many choose to place their dehumidifiers in basement or crawl spaces as they tend to get moist all year round. Moisture in basement and crawl space can damage your entire home.

TL;DR: The placement is very important. The ideal place to use a dehumidifier is in the most damp and moist area of the room or your home. 

How To Tell If Your Dehumidifier Is Working

It’s not always easy to tell whether the humidity levels are going down in a room, but there are a few ways to check that your dehumidifier is working:

Check the tank

how to clean a dehumidifier

The quickest way to make sure your dehumidifier is working is to look for water collected in the water tank.

If this is rising then it means the dehumidifier is taking moisture from the air and the humidity levels should be falling.

I have to empty my tank at least once a day and I would recommend checking yours frequently too.

Look at the humidistat

All modern dehumidifiers will have a built-in humidistat that actively measures the humidity levels of the room.

This is how it determines when to turn on and off, and most dehumidifiers will have a display screen showing the relative humidity.

If the humidistat shows the humidity is dropping, then it means your dehumidifier is working.

Use a hygrometer

If your dehumidifier doesn’t have a humidistat then you can use a hygrometer which will show you the current humidity levels in the room.

I would recommend checking this before you use the dehumidifier, and then a few hours afterward and you should see at least a slight reduction in the level of humidity in the room.

TL;DR: You can the water tank over time, the built-in humidistat or get a standalone hygrometer to check whether your dehumidifier is working or not.


How Many Years Does A Dehumidifier Last?

The life span of a dehumidifier ranges from 5 to 10 years but varies for each brand. Also, regular upkeep can maximize the lifespan of your chosen unit alongside helping it work better.

Is It Safe To Run A Dehumidifier Constantly All The Time?

The rule of thumb is to run a dehumidifier for at least 12 hours and only until the desired humidity level is maintained.

Anything more or less than that is not ideal. Learn about safety when using these devices here.

What Is The Minimum Temperature For A Dehumidifier To Work?

The minimum temperature for a dehumidifier to work is at least 60-65 degrees Fahrenheit.

Most dehumidifier brands vary with their requirements, but this is the standard temperature to run a dehumidifier.

Wrapping It Up

Unfortunately, there’s no exact answer for how long a dehumidifier will take to work.

In some parts of my home, the dehumidifier only has to run for a few hours at a time, but in other rooms, it has to run for days.

It generally all comes down to how much humidity there is and the efficiency of the dehumidifier.

Hopefully, this guide has helped to explain how long it takes for a dehumidifier to work and explained why it can sometimes take a longer or shorter time.

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Josh Mitchell


Josh Mitchell
My name is Josh and I am obsessed with home appliances. From portable AC units to heaters and air purifiers, I enjoy testing, learning and using these devices to improve the air quality inside my family home.

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Midea U Shaped Window Air Conditioner

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