Most branded purifiers lock you into proprietary cartridges at £40–£80 a pop that fit one machine only. There's a better way: high-grade MERV-13 media in standard 16×25 and 20×25 sizes that you can rebuy cheaply, forever. Here's how air-purifier filters actually work, when to change them, and the standard filters we recommend.
Shop MERV-13 filters — 10% off →Genuine 3M Filtrete MERV-13 (MPR 1900) — hospital-grade media that captures ~93% of airborne particles including pollen, fine dust, smoke and pet dander. Sold in pairs; lasts 6–12 months.
MERV-13 · MPR 1900 · fits 7-Fan XL & any 20×25 box · lasts 6–12 months
MERV-13 · MPR 1900 · fits 5-Fan Luggable & any 16×25 box · lasts 6–12 months
EPA H11 + activated-carbon layer · for the Exhalaron personal purifier
Not sure which size? 5-Fan Luggables and most 16×25 CR-style boxes use 16×25×1; the 7-Fan XL and 20×25 boxes use 20×25×1. Full sizing & cost guide →
| Proprietary brand filter | Standard MERV-13 (16×25 / 20×25) | |
|---|---|---|
| Typical price | £40–£80 each | from £29 per filter (£58 a pair) |
| Fits | one specific machine | any box using that size — no lock-in |
| Where to buy | the brand only | widely available; rebuy anytime |
| Grade | varies (often "HEPA-type") | true MERV-13, MPR 1900, ~93% capture |
| Running cost/yr | £80–£160+ | ~£58–£75 (one pair) |
The maths is simple: a purifier is only cheap if its filters are. Standard-size MERV-13 keeps your long-term cost low and puts you in control of when — and where — you rebuy.
Genuine 3M Filtrete MERV-13 in standard 16×25 and 20×25 sizes — 10% off with code STAROFFER. Ships from Oxford, free UK delivery over £100.
Shop replacement filters →If you're filter-shopping because your old purifier died — or the filters cost more than the machine is worth — a Luggable uses the same cheap standard MERV-13 you just read about.
369 m³/hr · <35 dB · uses 16×25 MERV-13
681 m³/hr · large rooms · uses 20×25 MERV-13
MERV-13 + activated carbon · odours & VOCs
Check the old filter's printed dimensions or your unit's manual. The two most common standard sizes are 16×25×1 inches (5-Fan Luggables and many CR-style boxes) and 20×25×1 inches (7-Fan XL and larger boxes). Matching the size is what matters — MERV-13 media of the right dimensions will fit and seal correctly.
For everyday indoor air, effectively yes. MERV-13 captures around 93% of airborne particles including PM2.5, pollen and smoke. Because MERV-13 has lower airflow resistance, a high-airflow box moves far more air through it — so real-world clean-air delivery often matches or beats a small sealed HEPA unit, more quietly and cheaply.
Most MERV-13 media lasts 6–12 months in a normal home. Replace sooner after heavy wildfire smoke, building work or if airflow visibly drops. See our full replacement-timing guide.
No — washing MERV-13 or HEPA media damages the fibres and destroys the electrostatic charge that traps fine particles. Pre-filters and mesh guards can be vacuumed or rinsed, but the main filter should be replaced, not washed.
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