When choosing an air purifier, the price on the box is only the beginning of the story. While the initial purchase can range from under £100 to over £700, the true financial commitment comes from the day-to-day running costs. The ongoing expenses for electricity and replacement filters can quickly add up, sometimes even surpassing the original price of the unit over its lifetime.

This guide provides a clear, data-driven look at the Total Cost of Ownership (TCO) for air purifiers in the UK. We will break down exactly how much you can expect to pay for electricity, how often you’ll need to replace filters, and which models offer the best long-term value. If you're just starting your research, our [Air purifiers - Uk ultimate guide] provides a complete overview of how these devices work.

(Disclosure: When you buy through links on our site, we may earn an affiliate commission at no extra cost to you. We recommend only products we believe in.)

 

The Two Main Running Costs: A Detailed Breakdown

To understand the true cost of owning an air purifier, you must look beyond the purchase price and focus on two critical factors: electricity consumption and filter replacements. These recurring expenses determine the long-term financial impact of the appliance.

 

Electricity Consumption: From Watts to Pounds Sterling

An air purifier's electricity cost depends on its power consumption (measured in Watts), how many hours you use it, and the price of electricity. Modern, energy-efficient models have a surprisingly low power draw, but costs can still mount up, especially if the device runs 24/7. For a deeper dive into appliance efficiency, see our [Guide - Energy].

The formula to estimate the daily cost is straightforward:

(Power in Watts / 1000) × Hours of Use × Cost per kWh (£) = Daily Cost (£)

Using the UK's energy price cap rate of 26.35 pence per kWh (for Q4 2025), a 40W air purifier running for 24 hours a day would cost approximately £0.25 per day, or about £92 per year. However, power consumption isn't constant. The most significant variable is fan speed. A model like the Dyson Purifier Cool Formaldehyde TP09 can use as little as 6W on its lowest setting but jumps to 40W on its highest. This is where an 'Auto Mode' becomes a key cost-saving feature. By using sensors to monitor air quality, it allows the purifier to run at a minimal, energy-saving level when the air is clean, only increasing power when pollutants are detected.

 

The Filter Factor: The Single Largest Recurring Expense

The filter is the heart of an air purifier and its most significant recurring expense. Most devices use a multi-stage system, typically including:

• A Pre-filter: Traps large particles like dust and pet hair.
• A HEPA Filter: Captures 99.97% of fine particles like pollen, mould, and pet dander.
• An Activated Carbon Filter: Adsorbs gases, odours, and VOCs.

For more detail on these components work, you can read our [Guide - air filter].

Filter costs vary dramatically, from under £20 to over £200, but the replacement frequency is just as important. A £30 filter that needs changing every six months (£60 per year) is more expensive than a £50 filter that lasts for a full year. Manufacturer recommendations range from 6 months to as long as 36 months, depending on the model and usage. This single factor can make a seemingly cheap purifier an expensive long-term investment.

 

Running Cost Comparison of Popular UK Models

Let's look at the specific numbers for some of the UK's most popular air purifiers. The data highlights a significant variation in long-term running costs between different models.

 

Annual Electricity Cost Comparison

The following table shows the estimated annual electricity cost for each model, calculated for 24 hours of daily use at the UK energy price cap rate of £0.2635 per kWh. The range reflects the cost from the lowest to the highest fan speed.

 

 

As the data shows, modern units are incredibly efficient on their lowest settings. However, the cost can increase tenfold on the highest setting, reinforcing the value of an 'Auto Mode' or using a correctly sized unit that can run effectively on a lower power level.

 

Annual Filter Cost Comparison

The table below normalises the manufacturer's filter price and recommended lifespan into a single annual cost, providing a direct comparison.

 

The Philips 2000i Series stands out with its exceptionally long filter life, resulting in the lowest annual cost. Conversely, models with shorter 6-month filter lifespans can quickly become more expensive to maintain.

 

Calculating the Total Cost of Ownership (TCO)

 

Total Cost of Ownership = Purchase Price + (Annual Electricity Cost x Years) + (Annual Filter Cost x Years)

To make the best financial decision, we need to combine the purchase price with the running costs over a typical ownership period. This is the Total Cost of Ownership (TCO), and it reveals the true long-term value of a product.

 

3-Year TCO for Popular Models

The following table projects the total expenditure for popular models over a three-year period. This provides the clearest picture of which air purifiers are the most economical in the long run.

 

 

Note: Electricity costs are estimated based on a medium setting. Purchase prices are indicative.

This analysis clearly shows that the initial purchase price can be misleading. The Levoit Core 300S, one of the cheapest to buy, also proves to be the most economical to own over three years due to its excellent energy efficiency and reasonably priced filters. The more expensive Philips 2000i remains competitive thanks to its very low annual filter cost.

 

The False Economy of an Undersized Purifier

Choosing a purifier that is too small for your room is a common and costly mistake. An undersized unit must run constantly on its highest fan speed to have any meaningful effect on air quality. This not only maximises electricity consumption but also clogs the filter much faster, leading to more frequent and expensive replacements.

A far more effective strategy is to select a unit with a Clean Air Delivery Rate (CADR) that is appropriately sized for your space. A common guideline is the "2/3 Rule," which suggests the purifier's smoke CADR rating should be at least two-thirds of the room's area in square feet. CADR is tested for three pollutants (smoke, dust, and pollen), but the smoke rating is the most useful benchmark as these are the smallest particles and the hardest to filter, making it a strong indicator of overall performance. This allows the device to run effectively on a quieter, more energy-efficient lower setting. For more on this, see our [Guide - air flow]. Running on a lower speed also has the significant benefit of reducing operational [Guide - noise].

 

Hidden Costs & Critical Considerations

Beyond electricity and filters, there are other factors to consider that carry their own "cost".

• Health & Safety Risks: Some purifiers use technologies like ionizers or UV-C lamps that can produce ground-level ozone as a byproduct. Ozone is a lung irritant that can worsen respiratory conditions. For maximum safety, it is best to stick with purifiers that rely solely on mechanical filtration (HEPA) and activated carbon.
• Environmental Cost: Used HEPA filters are contaminated waste and are not recyclable. They must be disposed of in general household rubbish, contributing to landfill. This is an important environmental consideration, especially for units that require frequent filter changes.
• Marketing Claims vs. Reality: UK regulations are strict, but it's wise to be sceptical of vague claims like "allergy-free environment." Look for specific, quantified data (e.g., "removes 99.97% of particles") rather than broad health promises. An air purifier helps reduce pollutants but is not a substitute for proper ventilation.

 

Buying Guide: How to Choose a Cost-Effective Air Purifier

To ensure you get the best long-term value, follow this simple checklist:

1. Calculate Your Room Size: Measure your room's square footage and use the "2/3 Rule" to find the minimum CADR you need. This is the most crucial first step.
2. Check the Wattage: Look at the power consumption range in Watts. An efficient model should ideally use less than 30W on its highest setting.
3. Compare Filter Life & Cost: Check the recommended filter lifespan and the price of official replacements. Aim for a lifespan of at least 12 months to minimise recurring costs and waste.
4. Use TCO as Your Guide: Refer to our Total Cost of Ownership analysis. A slightly higher upfront cost for an efficient model with a long-lasting filter will almost always save you money over the life of the appliance.

Based on your TCO analysis, you can identify which models offer the best value for different needs. For example, a highly economical unit might be a top pick in a guide to the [Best under £150], while a more powerful but still efficient model could be a strong contender in a list of the [Best air purifiers for large rooms].

 

Frequently Asked Questions (FAQs)

 

Is it expensive to run an air purifier 24/7 in the UK?

It can be, but it depends entirely on the model. An energy-efficient unit on its lowest setting can cost as little as £5-£10 per year to run continuously. However, a powerful or inefficient model running on its highest setting could cost over £100 per year in electricity alone.

 

Are cheap air purifiers a false economy?

Often, yes. A cheap-to-buy purifier may have high running costs due to an energy-inefficient motor or expensive, short-lived filters. Over 2-3 years, it can easily end up costing more than a pricier but more efficient model.

 

How much do HEPA filter replacements cost?

The cost varies significantly. For popular home models, official replacement filters typically cost between £25 and £60. The key is to check the recommended replacement frequency, as this determines the annual cost.

 

Do I need to use the official manufacturer's filters?

It is highly recommended. While cheaper third-party filters are available, they can compromise the purifier's performance, may not fit correctly, and could void your warranty.

 

Internal Links Included

• Air Purifier Guide to Air Flow
  
• The Ultimate UK Guide to Air Purifier Filters
  
• A Quiet Guide: Understanding Air Purifier Noise in the UK
• Best under £150: Linked in the buying guide.
• Best under £250: Linked in the buying guide.