Does An Air Purifier Use A Lot Of Electricity? Real Numbers Inside!

Ever wondered how much electricity an air purifier uses? I’ve got you covered!

Read on to see real power measurements and find out the facts.

Does an air purifier use a lot of electricity?

does an air purifier use a lot of electricity

The short answer is that typical air purifiers use a small amount of electricity (about 55 watts or less). The fan speed setting affects their power use but most use less than 70 watts on their highest or turbo fan speed.

Think of them as using roughly the same electricity as a 60W incandescent light bulb – especially on low or medium speeds which are the most commonly used settings.

Naturally, the size and particular model will make a difference, too. For example:

  • Small room air purifiers have a very small fan (low air flow rate) and use only a handful of watts.
  • Medium to large-room purifiers can use anywhere from 5 to 65W.
  • Some special modes such as Sleep mode or Ultra-quiet mode use significantly less than average settings.
  • More powerful models with a very high speed fan mode can use up to around 85-90W but much less on everyday settings.

In fact, I’ll show you some specific real-world measurements on some popular models I took myself to help show what I mean.

How much electricity does an air purifier use? (Real measurements)

1. Small purifier example

Levoit Core 300 power measurement wattage images

In this picture, you can see the power, in watts, drawn by a Levoit Core 300 small air purifier on 4 settings: sleep mode, low, medium, and high.

Levoit Core 300 HEPA air purifier product image front

Shown here is the Levoit Core 300 purifier I measured power use for.

I’ve measured dozens of different models and I’ve found that the power used by air purifiers varies from model to model but is generally fairly similar.

To give a general idea of what you can expect I measured the electricity use for a Levoit Core 300 purifier. Here’s what I found:

Fan speed Power (watts)
Sleep (ultra-low) 10.4
Low 26.7
Medium 30.3
High 43.3

2. Large purifier example

Winix HR900 air purifier power measurements in Watts diagram

Shown here are power measurements made with a Kill A Watt power meter for a Winix HR900 model large room purifier.

Product image of Winix HR900 Ultimate Pet air purifier

Image of the Winix HR900 model large purifier I measured power use for.

Let’s take an example of a large room air purifier, the Winix HR900, suitable for rooms up to 360 square feet. How much electricity does this model use?

The power draw of a purifier depends on several things, but here’s what I measured:

Fan speed Power (watts)
Sleep (ultra-low) 4.3
Low 7.8
Medium 10.2
High 13.9
Turbo 46.6

Bear in mind again that this is a large room air purifier with a higher-power fan inside. How can it be about the same power use as some medium room models?

It comes down to several things:

  • The design quality.
  • The efficiency of the electric fan and motor.
  • Careful use of the motor to keep power consumption low.

Not all brands and models are equal – it can vary, but generally speaking, the power use is usually from about 15 to 55 watts for the most popular HEPA purifiers on the market.

How many hours a day can you run an air purifier?

how many hours a day can you run an air purifier

You may hear different recommendations, but basically around 12 hours minimum is a good rule of thumb. However, leaving it on all day is preferable for maintaining clean air.

Some people who live in areas with particularly nasty air pollution (for example: outdoor fires) may need to leave theirs running on a higher setting all day. For light duty air cleaning you may be ok with 12 hours or even 8. 

In my experience, dealing with problems like dust and allergies need at least that much, but you’ll often get the best results just by leaving it running all the time. 

Models with timer functions or auto sensing

Some models include an off-timer to shut the unit off automatically to prevent it from running while you’re not around if preferred. Others, such as some models from GermGuardian, Levoit, and Winix even have built-in sensors that can change the fan speed automatically based on the air condition.

Those are a “set it and forget it” type and pretty much eliminate the need to worry about how much time or changing the speed yourself.

How much does it cost to run a purifier 24/7?

I’ll use an example based on typical use. Let’s use the following numbers:

  • Fan speed & power use (estimates): we’ll use 9 hours on low speed (overnight) at 15W and 15 hours (during the day) on medium at 25W for a total of 24 hours of use each day.
  • Power company rate: we’ll use an average power rate for Georgia, USA: $0.1101 per Kilowatt-hour (kWh).

Based on this, here’s a table showing how much it costs to run an air purifier 24/7:

Air purifier electricity cost table

Time Cost
24 hours $0.05616
1 week $0.39
1 month $1.74
1 year (365 days) $20.50

As you can see, it costs very little to use a typical air purifier on low or medium settings. Of course, that would go would go up by a factor of about 2x if it’s left running at the highest speed all the time, but even then it’s still not much!

Air purifiers increase your electric bill by a very small amount – not even close to the amount of power that energy hogs like air conditioners, ovens, and heaters use.

How long does it take an air purifier to clean a room?

how long does it take an air purifier to clean a room

The amount of time it takes an air purifier to clean a room depends on the purifier’s airflow rate (cubic feet per minute [CFM] or CADR rating) and the fan setting. This can be from about 20 minutes to 2 hours depending on the purifier’s air cleaning efficiency and the room size.

Using a quieter (lower speed) fan setting will increase the time by a factor of at least several times longer. Note that the clean air delivery rate (CADR) rating is based on the highest setting the purifier has.

How long does it take air purifier to clean a room diagram

This diagram helps to explain room volume vs air purifier cleaning. You’ll need manufacturer specifications to do this (brand name air purifiers normally provide this) and the width and length of a room to estimate the size in cubic feet.

Manufacturers usually include one or more specifications that tell you both their recommended room size (in square feet) and/or the amount of air they can move in one minute (CFM, or cubic feet per minute). The best air purifier brands include lab-tested Clean Air Delivery Rate (CADR) specifications.

A CADR rating helps you better understand how efficiently a purifier can get rid of air particles. It provides a lab-tested demonstration of how efficiently the product can remove smoke, dust, and pollen particles.

Example: Finding the time a purifier takes to clean a room

Let’s say you have a room with a size of 10 x 16 x 8 feet (width x length x height). 10 feet x 16 feet x 8 feet = 1,280 cubic feet. Let’s use a popular model, the GermGuardian AC4825, with a smoke CADR rating of 108.

The time it would take to cycle the room air on the high fan setting would be:

1,280 / 108 = 11.9 (about 12 minutes)

For using other fan settings, some rough estimates would be:

  • Medium speed: (say 1/2 of high) about 2x the time, or close to 30 minutes.
  • Low speed: (let’s say that’s 1/5 of high) about 5 x the time, or about 1 hour.
  • Ultra-low speed/sleep mode: let’s say that’s about 1/20th the fan rate: about 20x the time (nearly 2 hours).

Generally speaking, dirtier air or more pollution will take more time to clean and freshen the air, resulting in a difference you can notice. That’s one of the reasons why running the air purifier for at least 12 hours is recommended. 

Should you run a HEPA filter all day?

should you run a hepa filter all day

It’s absolutely fine to leave a purifier or other system with a HEPA filter running all day. The filter will only lose cleaning effectiveness after trapping a high amount of contaminants.

 In fact, in a lot of ways, it’s preferred to do that. For example, after air cleaning hasn’t been performed for a long time there are often enough contaminants like dust mite by-products, pet dander, or dust to cause allergic or other symptoms. That’s especially true for people who are more sensitive than others.

During the time you’ll have to run your purifier or filtration system again and get the problem under control you’ll still have to deal with the symptoms. Therefore you’re often better of just leaving the air cleaner or air system with a high-efficiency particulate air (HEPA) filter running on a lower setting.

HEPA filters aren’t time-sensitive. In other words, they don’t become “used up” only due to time, but rather that can trap and remove a certain amount of particulates regardless of the amount of time that has passed.

The life of an air filter depends on the level of contaminants in the air – heavier air quality problems will fill the filter’s fibers faster than lesser problems.

Is it okay to leave an air purifier on all night?

is it okay to leave air purifier all night

Yes, it is absolutely fine to leave an air purifier on all night. The main considerations are the noise level and your ability to sleep with it nearby. I’ll explain what I mean as we go.

Most manufacturers will in fact recommend that you leave it running all night long as this is the easiest way to achieve the best possible results. Continuous filtration is the best way to keep your home’s air clean, after all.

Ultra-quiet or sleep modes

As I mentioned, there are a few things to consider. If you’re a light sleeper you might not want to be woken up by the sound of a fan running. If you’re very sensitive to sound when sleeping (like me!) then you’re best off picking a model with a sleep mode or ultra-low noise mode or placing it further away.

Low noise modes on a purifier are a mode in which the fan still runs but at a very, very low speed – so quiet in fact that it’s nearly impossible to hear them!

Brightness in a dark room (controls and lights)

Similarly, if you need a fairly dark room to sleep well, the bright LED indicators or control panel backlights on some models could be a distraction. I recommend you shop for a model with a “night” or “dark” mode or other low-brightness features.

On the other hand, if you’ve already bought one you may need to cover LEDs with black electrical tape or something similar to stop the problem.

Are air purifiers worth it?

are air purifiers worth it

As most people deal with air quality problems that are in of several common categories, yes – a good quality air purifier properly matched to the room size is a good purchase and can improve your quality of life.

In fact, for some people, owning one is almost a necessity! For example, those with severe allergies or respiratory problems find them to offer very helpful relief and make their life more comfortable and less distracting.

What makes an air purifier a good choice?

There are several factors that definitely matter when it comes to getting results and healthy air from an air purifier:

  • The correct size for the room it’s used in: Air purifiers can only move a certain amount of air (the cubic feet per minute rating, or CFM) based on their size and airflow rate. An undersized model simply cannot move enough air in a large room, for example.
  • A quality product with good cleaning efficiency: They don’t even need to be expensive! However, you do need a good quality product with a good cleaning ability. This is often provided for better brands. Look for the Clean Air Delivery Rate to know what to expect.
  • Using the correct TYPE of purifier: Ionizers, ozone generators, and other oddball technologies do not work the same as a HEPA purifier. A HEPA purifier genuinely removes unwanted elements from the air while adding nothing back to the air. Other types produce ions or ozone to supposedly trap particulates, but either aren’t effective or can cause irritation to body parts. In some cases, they can actually even be harmful.

In fact, HEPA filters are proven to remove some types of germs, microbes, and viruses from the air that can otherwise cause sickness or other symptoms. A good air purifier (for a medium-sized room, for example) costs below $100 these days, so it’s not necessary to spend a ton of money.

I wouldn’t call them an essential item for every household, but a good one is certainly worth the money. I’ve had multiple problems they’ve helped me with such as dust and pet allergens.

It’s wonderful to not be trapped at home around unclean air but instead breathe in fresh, clean air!

Grant Williams

About the author

Grant is a professional engineer by trade and has experience with both maintenance and do-it-yourself home projects. He enjoys sharing his expertise & ideas with others to help them improve their comfort and quality of life. Read more »

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