Which size do I need?
| Your purifier / box | Filter size | Recommended |
|---|---|---|
| Luggable Ultra (5-Fan) & most 16×25 CR boxes | 16×25×1" | 3M Filtrete MERV-13 16×25 — £75/pair |
| Luggable XL (7-Fan) & 20×25 boxes | 20×25×1" | 3M Filtrete MERV-13 20×25 — £58/pair |
| Exhalaron personal / desktop purifier | 6" or 6.5" round | Exhalaron EPA H11 — £32 each |
If you're not sure, read the dimensions printed on the edge of your current filter, or measure the slot. Standard imperial furnace-filter sizes (16×25, 20×25) are the whole point: you're never tied to one supplier.
What do filters actually cost per year?
A single pair of MERV-13 lasts most homes 6–12 months, so a realistic annual spend is one pair, £58–£75 — roughly £0.11–£0.20 a day for clean air. Compare that to proprietary "HEPA-type" cartridges at £40–£80 each, often needed 2–3× a year: £80–£160+ annually for the same job.
- MERV-13, MPR 1900 — captures ~93% of airborne particles: PM2.5, pollen, fine dust, smoke, pet dander, many bacteria and virus-carrying droplets.
- Genuine 3M Filtrete media — not a generic offcut; consistent pleat density and electrostatic charge.
- No lock-in — standard sizes mean you can rebuy from us or anyone, forever.
Signs it's time to replace
- It's been 6–12 months since the last change.
- Airflow from the unit has visibly weakened.
- The media looks grey/loaded, or smells musty.
- You've just been through wildfire smoke, decorating dust or a house move.