What filter does a Holmes HM3800 take?
It takes the Holmes HWF65 Filter (Type C) — OEM part number HWF65.
Holmes HM3800, evaporative humidifier, console.
Lowest verified price: $14.95 — aftermarket, 1 filter, Filters Fast H65-C at FiltersFast. Free economy shipping on orders $99+ (lower 48); a fee applies below that. Checked 2026-11-11.
Buy the HWF65 on Amazon — HWF65Amazon search for the exact part number (no single listing is endorsed). Amazon price is shown on Amazon; we do not quote it here.
The part, in brief
| Part | Holmes HWF65 Filter (Type C) |
|---|---|
| Replacement interval | Filter life 1 to 2 months (FiltersFast spec for its H65-C replacement). |
| Per change | HM3800 and HM3850 need THREE filters; HM4000 needs TWO (BestAir / DiscountFilters fitment notes). Others use one. |
| Equivalents | BestAir / BestAir Pro H65 / H65-C, Filters Fast H65-C, DiscountFilters (AIRx) AXPPF-HWF65, BestAir ALL-2 |
Verified prices
| Option | Price | Store & shipping |
|---|---|---|
| Aftermarket 1 filter, Filters Fast H65-C | $14.95 | FiltersFast Free economy shipping on orders $99+ (lower 48); a fee applies below that · Checked 2026-11-11 · source |
| Also checked 2-pack AIRx replacement | $26.99 | DiscountFilters Free shipping on orders $70+ at DiscountFilters; a fee applies below that · Checked 2026-11-11 · source |
| Also checked 4-pack AIRx replacement | $44.95 | DiscountFilters Free shipping on orders $70+ at DiscountFilters; a fee applies below that · Checked 2026-11-11 · source |
Full record with every price, source and date: Holmes HWF65 Filter (Type C) page.
Finding the model number on a Holmes
Model numbers are on the bottom of the unit, starting with 'HM'. Holmes, Sunbeam and Bionaire are sister brands (Newell) and share wick fitments — the filter 'type' letter (A/B/C/D/E) is printed on the old filter's packaging and in the manual.