Do air purifiers use a lot of electricity?
In one line: it depends entirely on the model's wattage. An efficient unit draws 6–18 watts (a few to a couple of tens of pounds a year run continuously); a powerful HEPA tower can draw 60–120 watts, costing far more. Wattage — not brand — decides the bill.
How to work it out
Yearly cost = (watts ÷ 1000) × hours per day × 365 × price per kWh.
At a typical UK unit rate around 28p/kWh, running continuously (24 h/day):
| Unit power | Approx. yearly electricity |
|---|---|
| 15 W (efficient) | ~£37 |
| 30 W | ~£74 |
| 60 W | ~£147 |
| 100 W (powerful tower) | ~£245 |
Run it fewer hours or on a lower speed and the cost drops proportionally. Don't forget filters as the other running cost — see how often to change filters.
Why efficiency matters more than you'd think
Because a purifier only cleans while it's on, the ones that help most are the ones you can afford to leave running. A high-airflow, low-wattage design (like a Corsi-Rosenthal box) delivers a lot of clean air per watt, so it's cheap to run 24/7 — whereas a 100 W tower often gets switched off to save money, and then cleans nothing.
Next step
Work out the exact cost for any model with the running-cost calculator, or see low-wattage picks at Best Air Purifier UK.
FAQ
Is it expensive to leave an air purifier on all night? For a low-wattage unit, no — an 8-hour night at 15 W is roughly a penny or two. A 100 W tower costs several times more.
Where do I find the wattage? On the label or spec sheet (look for watts at the speed you'll use). Then use the formula above.