How Long Should You Run An Air Purifier? The Ultimate Guide

by Véronique Raymond
women near air purifier

You just bought the best air purifier, which is a worthy investment as it means you’ll start breathing clean air into your body. However, you might be wondering, ‘how long should you run an air purifier?’ The short answer is 24 hours per day if you’re always in the house and want to keep your indoor air quality high, but this may depend on the type of air purifier.

Furthermore, that implies you should leave your air purifier running all night and day without switching it off. In this guide, we’ll explore everything you need to know about an air purifier’s runtime, regardless of whether you’re a veteran or beginner in the air purifying world.

How Long Should You Run an Air Purifier?

You should keep your air purifier running throughout if you spend most of your time indoors. That’s because, with the constant build-up of airborne particles, pet dander, dust mites, indoor pollution, and allergens, the clean air will get re-contaminated within three to four hours if your air purifier was turned off.

With constant clean air, you can breathe more comfortably. Furthermore, allergies such as sinuses and cough will become the least of your concerns. To optimize the performance, set the purifier to the maximum speed for two to three hours before switching it back to the lowest speed to maintain the room air quality standard.

Furthermore, run the unit daily or as frequently as possible to make sure the air remains fresh and clean each time you return home.

How Long Does It Take an Air Purifier to Clean the Air in a Room?

On average, it would take your air purifier anywhere between 30 minutes and 2 hours to clean the air in a room. However, you’ll feel a difference in the air quality within 20 minutes of the unit running.

For the unit to be immensely effective, it highly relies on the air changes by the hour (extraction rate), the room size, and the model. The extraction rate computes the air quantity that can be cleaned from a room within an hour.

For instance, a HEPA air cleaner running at 15 minutes per charge or 4 air changes per hour would only require half the time to clean the air compared to an air cleaner that runs at 2 air changes per hour or 1 air change every 30 minutes.

Weather and location also play a key role in how fast an air purifier works. With the increase in pollutants such as pollen during summer, an extended period is required for an air purifier to clean the air and prevent allergies.

Lastly, the air cleaner should also have sufficient airflow capacity to fulfill the size of the room.

How Much Does It Cost to Run an Air Purifier?

It functions like other electronic appliances in your home and in general, is energy efficient. Here’s the breakdown of the cost and energy that air purifiers use.


Rate of Electricity (the cost in kilowatts per hour) by the hours of operation by the power consumption in kilowatts (kW)


  • Power consumption of the unit (measured in watts): You’ll find this information the specs of your air purifier
  • The electricity rate ($/kWh): You’ll find this information in your electricity bill
  • Hours of operation: The duration that the air purifier has been in use

For instance:

The operation cost of an air purifier with a power consumption of 0.04kW (40W) for 720 hours (30 days) with the electricity rate is as follows:

0.04 By 720 By 0.1 = $2.88

LEVOIT Air Purifiers for Home Bedroom, H13 True HEPA Filter Air Purifier for Allergies, Smoke, Pet Dander Odor, Dust, Mold, Pollen, Quiet Air Cleaner with 3-Speed Fan and Night Light, LV-H132 White

Should You Run Your Air Purifier If You Don’t Spend Most of Your Time at Home?

For starters, we recommend that you complete the cost of running the air purifier year-round to determine whether or not it’s within or above budget. The reason is that the air in your room will become contaminated again upon turning off the air purifier. Additionally, you’ll need to repeat the air cleaning phase followed by maintenance.

Therefore, if you can afford to have your air purifier running day in and day out, then you have free rein to do so. However, if you spend a large period of time away from home, you can save money by turning off your unit and investing in a smart air purifier that allows you to automatically power it on before you get home and enjoy clean air by the time you arrive.

How to Get Your Air Purifier Running

To get started, follow the straightforward steps below.

Step 1

To clean contaminated air, start by powering up your unit and setting it to the highest fan speed for up to 3 hours. If your machine is designed to cover up to 500 square feet, it’ll take about 90 minutes to cover half of the area, and we recommend running this twice to thoroughly cover the area.

Step 2

Once you clean the air, you can switch your machine to low or medium speed to maintain the purified air. It’s worth keeping in mind that you should avoid turning off your air purifier if you want to maintain it at a low or medium speed.

Each time you need to leave your home for a while, consider turning off the unit. However, once you get home, repeat step 1 before setting the air purifier to a low or medium setting.

Should You Turn Off Your Air Purifier When You Go to Bed?

No! That’s because breathing clean air is equally as important when you’re asleep as when you’re awake. While you may not realize it, breathing clean air promotes quality sleep. By powering up the unit, you can effectively eliminate dust, bacteria, and pollen while you sleep, allowing you to get a good night’s rest.

Should You Open Your Windows When Your Air Purifier Is Running?

The answer to this question is subjective because it’s based on air quality in your home. If the air is polluted, we recommend keeping your windows closed throughout and allowing your air purifier to work its magic. Nevertheless, if the air is clean, we recommend allowing fresh air to flow into your home then closing the windows afterward.

The Verdict: How Long Should You Run an Air Purifier?

Many people have a misconception that running an air purifier for a few hours is enough to provide clean air for the rest of the day. That couldn’t be further from the truth as airborne contaminants are constant, and an air cleaning machine is designed to operate throughout.

Each time an air purifier stops functioning, airborne pollutants will begin building up and re-contaminating your home. Resultantly, the entire air purification process must restart, and it takes a while to achieve the best outcome.

On the flip side, leaving an air purifier running continuously can cause a spike in your electricity bill and maintenance costs of keeping the unit functioning seamlessly. That’s because the air filters wear out prematurely and require regular filtration replacement. Nevertheless, in the grand scheme of things, that’s a small price to pay for the overall health and wellbeing of you and your household.

Lastly, it’s worth keeping in mind that an air purifier isn’t a magic tool. Therefore, you can’t solely rely on this handy machine to keep the air in your home clean. You need to cultivate the habit of keeping your home spick and span to avoid air pollutants such as dust.


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