Dreo
Dreo HM311S
Dreo does the thing most ultrasonic makers leave to a separate accessory listing: it ships a demineralisation cartridge and tells you when to change it. That single decision is why the HM311S sits in the no-white-dust filter on this site while several pricier ultrasonics do not. The rest is a competent $50 bedroom unit - 4-litre top-fill tank, real humidity sensor, app, 28 dB. Independent testing found it better suited to rooms under about 200 square feet than the 300 on the box, which is roughly where the arithmetic lands too: 300 sq ft wants 1.2 gallons a day and would drain the tank in about 21 hours rather than 32.
The room-size claim, reconciled
195 sq ft supported · box says 300 sq ft
The box says 300 sq ft. By the winter load calculation this output supports about 195 sq ft — the claim is 1.5× the room the machine can hold.
Holding 300 sq ft takes about 1.22 gal/day, which drains this 1.06-gallon tank in roughly 21 hr — against the 32 hours Dreo advertises, which is measured at the lowest setting.
What a year costs
Dreo's demineralisation cartridge three-pack is around $18 and the manual asks for a change every two months in season. Electricity assumes the rated 30 W for 12 hours a day across a 150-day heating season at 16¢ per kilowatt-hour.
Specifications
Maintenance profile
- Top fill
- Yes
- Replaceable media
- Demineralisation cartridge
Facts, not a score. Which of these matter depends entirely on whether the unit ends up somewhere you will actually clean it.
Features
- Demineralisation cartridge included, not sold separately
- Top-fill 4L tank
- Humidity sensor and auto mode
- Dreo app with scheduling
- 28 dB on low
Pros
- Ships with a demineralisation cartridge, which is the whole white-dust problem solved in the box rather than in a follow-up order
- Owners on hard water report no dust on dark furniture, which is the specific thing they bought it for
- Genuinely cheap for a unit with a real humidity sensor and app control
- Top filling and a tank shape wide enough to get a hand into for cleaning
Cons
- The cartridge is a recurring cost the sticker price hides - roughly $24 a year at Dreo's stated change interval
- TechGearLab's testing put its useful room size at closer to 200 sq ft than the 300 claimed
- No warm mist, so in a cold bedroom the mist is noticeably chilly
- The app is another account and another device on the network for what is a $50 appliance
What owners say
Summarised from owner discussions and long-form owner reviews. Nobody here has used this unit.
Dreo's cheapest smart unit, and the interesting thing about it is a decision most makers at this price avoid: a demineralisation cartridge in the box, with a stated change interval. That single choice is why it appears in this site's no-white-dust filter while several pricier ultrasonics do not.
The rest is a competent bedroom humidifier. A four-litre top-fill tank, a real sensor, auto mode, app scheduling, and a quiet lowest setting. Independent testing puts its practical room closer to 200 square feet than the 300 claimed, which is roughly where the arithmetic lands too. Buy it for a bedroom on hard water and it does the job; buy it as a 300 sq ft room humidifier and it will not.
What owners like
- Ships with a demineralisation cartridge, which is the white-dust problem solved in the box rather than in a follow-up order
- Owners on hard water report no residue on dark furniture, which is specifically what they bought it for
- A real humidity sensor, auto mode and app control at $50 is unusually complete for the price
- Top fill with a tank wide enough to get a hand into for cleaning
Common complaints
- TechGearLab's testing puts its useful room size closer to 200 sq ft than the 300 on the listing
- The cartridge is a recurring cost that the sticker price does not hint at, and the change interval is short
- Cool mist only, so in a cold bedroom the mist is noticeably chilly
- It is another app and another account for what is a $50 appliance
Questions owners ask
Does it really avoid white dust?
What do the cartridges cost?
How big a room does it suit?
Dreo HM311S, head to head
Looked at alongside it
More from Dreo →
Dreo
Dreo HM512S
A litre more tank than the HM311S and a bigger room-size claim, from the same playbook: demineralisation cartridge in the box, humidity sensor, app, top fill. The 500 sq ft on the listing is the least defensible number Dreo publishes - that room calls for about 2 gallons a day, which would take the 5-litre tank down in roughly 16 hours against the 42 advertised. Treat it as a 250-300 sq ft machine and it is a good one. Against the HM311S it buys a litre of water and an aroma tray for $25; against Levoit's Classic 300S at a similar price it buys the demineralisation cartridge Levoit charges extra for, and gives up the longer-established app.
185 sq ft supported · box says 500 sq ft
Dreo
Dreo HM713S
Dreo publishes 500 mL/hr for this one, which is 3.17 gallons a day and puts it in the same real-output bracket as Levoit's LV600S at a slightly lower price. It also keeps the demineralisation cartridge, so unlike the Levoit it can run tap water without decorating the room. The 550 sq ft claim is close to what 3.17 gal/day actually supports - around 780 by the psychrometrics - making this one of the few portable ultrasonics whose room-size number is conservative rather than aspirational. The catch is the same as every hybrid: at the output that justifies the claim, the 6-litre tank is empty in about twelve hours.
781 sq ft supported · box says 550 sq ft
Vicks declines to put a square-foot number on this one, describing it only as a medium-room unit - which, given how the rest of the category behaves, is its own kind of honesty. A 4.5-litre tank running 30 hours works out to just under a gallon a day, the same ballpark as everything else at this price. Dual scent-pad slots, a variable output dial, no filter. The usual ultrasonic caveats apply and the tank neck is narrow enough that cleaning it properly means a bottle brush.
234 sq ft supported