ConsFirst / Humidifiers / Compare
Dreo HM311S 4L Smart Humidifier vs Blueair InvisibleMist Humidifier H35i
Which one has the downsides you can live with?
We may earn a commission when you buy through our links. It never changes what we report. Learn more
The short answer
Dreo HM311S 4L Smart Humidifier ranks higher (#2 vs #3 of 8) and scores better on humidifying power, quietness, tank & runtime. Blueair InvisibleMist Humidifier H35i wins on easy cleaning, running cost, durability.
The biggest complaint about the Dreo HM311S 4L Smart Humidifier is leaks and cracked tanks; for the Blueair InvisibleMist Humidifier H35i it's small tank. Pick the one whose catch bothers you less.
Side by side
| Dreo HM311S 4L Smart Humidifier | Blueair InvisibleMist Humidifier H35i | |
|---|---|---|
| Rank in humidifiers | #2 | #3 |
| Price tier | $ | $$ |
| Type | Ultrasonic | Evaporative |
| Amazon 1–2★ share | 10% | 14% |
| Overall score | 3.7 | 3.7 |
| Humidifying power | 3.5 | 3.0 |
| Easy cleaning | 4.5 | 5.0 |
| Quietness | 4.0 | 3.5 |
| Tank & runtime | 3.5 | 3.0 |
| Running cost | 3.5 | 4.0 |
| Durability | 3.0 | 3.5 |
Price tiers: $ under $60 · $$ $60–150 · $$$ over $150. Highlighted = clearly better (a score gap of 0.3 or more, or a 1–2★ share at least 3 points lower). Scores are explained, with sources, on each product's page.
Top complaints
Dreo HM311S 4L Smart Humidifier
- Leaks and cracked tanks
Leakage (200 of 227 mentions) and durability (179 of 229) are negative aspects on Amazon. Owners report water leaking from the bottom, units breaking within two months, and cracked tanks.
- Feels less sturdy; small tank without a handle
Wirecutter says the construction doesn't feel as durable as its other picks, the 4 L tank is smaller than they'd like, and it has no carrying handle.
Source: Wirecutter - White residue with tap water
Wirecutter says to use distilled or filtered water, since minerals in tap water can leave white residue or particulate matter in the air.
Source: Wirecutter - Not the quietest
CNN Underscored measured an average of 34 dB and called it not as quiet as others it tested. It also has no on-unit sleep-mode button.
Source: CNN Underscored
Blueair InvisibleMist Humidifier H35i
- Small tank
Wirecutter says the 0.9-gallon tank falls just below its 1-gallon guideline, so larger rooms or very dry climates will mean more refilling.
Source: Wirecutter - Filter cost
The Spruce says the wick filter costs about $30 every six months or so, and Wirecutter says it is designed for a roughly six-month replacement cadence.
Source: The Spruce, Wirecutter - Louder than ultrasonic, and no visible mist
Wirecutter notes its fan makes it louder than an ultrasonic model, though still well below conversation level. The Spruce reports that testers of evaporative models, including this one, wished they could see mist to know it was working.
Source: Wirecutter, The Spruce
Who should pick which
Pick the Dreo HM311S 4L Smart Humidifier if
Bedrooms and nurseries up to about 300 sq ft
Tight budgets that still want auto mode and an app
Easy cleaning
Skip it if: You need to humidify a large room; Light sleepers who want near-silence; You won't use distilled water
Pick the Blueair InvisibleMist Humidifier H35i if
People worried about mold and slime
Bedrooms (no wet mist or fog)
Tap-water users who want an app
Skip it if: You want to see mist to know it's working; You need a big tank for a large room; You want near-silent operation
We don't list prices — they change daily. Paid links.