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Dreo Smart Humidifier HM311S 4L Review | 43 Data compared

Avg. price in UK: ~£60
Avg. price in US: ~$50
Humidification rate: 250 ml/h
Maximum room area: 27.87 m²
Water tank capacity: 4 L
Maximum operating time: 36 hours
Maximum noise level: 32 dB

Dreo Smart Humidifier HM311S 4L review. Compare 43 technical specifications and user reviews to see how this product ranks in the Humidifiers category and whether it is worth buying.

7.9

Very good

7.6

Very good

9.2

Exceptional

8.5
Bedroom use
Score components:
35.0%
7.5
Maximum noise level
25.0%
7.4
Maximum operating time
20.0%
10
Timer
20.0%
10
Automatic low-water shut-off
6.2
Large rooms
Score components:
35.0%
6.1
Humidification rate
30.0%
4.4
Maximum room area
25.0%
6.8
Water tank capacity
10.0%
10
Hygrostat
7.0
Plant care
Score components:
30.0%
10
Hygrostat
25.0%
6.1
Humidification rate
25.0%
6.8
Water tank capacity
20.0%
4.0
360° nozzle

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Verdict

The Dreo Smart Humidifier HM311S features a 4-litre top-fill tank and operates via a 26W ultrasonic dual-intake system, delivering cool mist through a 4-inch wide, 30° tiltable nozzle to cover up to 300 square feet. It includes a built-in precise humidity sensor, auto mode, an integrated essential oil aromapad tray, and a smart ambient LED light indicator. Key advantages include an ultra-quiet 28dB acoustic operation, a long runtime of up to 32 to 36 hours on its lowest setting, an easy-to-clean modular design, and robust smart connectivity via the Dreo app, Amazon Alexa, and Google Assistant. However, some users have reported drawbacks, including potential water leakage, a loose tank lid that does not lock in place, and a lack of a built-in carry handle for the water tank.

Technical Specifications of humidifier Dreo Smart Humidifier HM311S 4L

Overall score

7.9

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Popularity

What it is: An indicator based on the number of reviews received by products in the Humidifiers category.

When it matters: When you prefer products in the Humidifiers category that have been chosen and reviewed by many other buyers.

Performance

7.2

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Technology

What it is: The method the humidifier uses to turn water into moisture for the room.

When it matters: Technology affects mist temperature, visible output, maintenance needs, and sensitivity to minerals in the water.

Importance: LOW

ultrasonic

Humidification rate

What it is: The maximum amount of water the humidifier can release into the air per hour.

When it matters: A higher rate raises room humidity faster and is more useful in dry or larger spaces.

Importance: HIGH

Good value: At least 300 ml/h

Maximum room area

What it is: The largest room floor area the humidifier is recommended to cover.

When it matters: A larger coverage rating is important for open-plan spaces and larger bedrooms or living rooms.

Importance: HIGH

Good value: At least 40 m²

Water tank capacity

What it is: The usable amount of water the humidifier’s reservoir can hold.

When it matters: A larger tank generally needs fewer refills and can support longer operation between top-ups.

Importance: HIGH

Good value: At least 4 L

Maximum operating time

What it is: The longest stated operating time from one full water tank.

When it matters: Longer runtime means fewer refills during overnight use or extended daily operation.

Importance: HIGH

Good value: At least 24 hours

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Features

8.4

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Warm mist function

What it is: Indicates whether the humidifier can produce warm mist as well as cool mist.

When it matters: Useful when you want warmer output in cool weather instead of cool mist alone.

Importance: HIGH

Good value: yes

Aromatherapy support

What it is: Indicates whether the humidifier supports the safe use of aromatic oils or fragrance media.

When it matters: Useful if you want to add fragrance without putting oil directly into the water tank.

Importance: MEDIUM

Good value: yes

Dedicated aroma compartment

What it is: Indicates whether the humidifier has a separate compartment for aroma pads or essential oils.

When it matters: A dedicated compartment keeps fragrance media separate from the main water tank.

Importance: LOW

Good value: yes

Automatic low-water shut-off

What it is: Indicates whether the humidifier switches itself off when the water level becomes too low.

When it matters: This safety feature helps prevent the unit from continuing to run with an empty tank.

Importance: HIGH

Good value: yes

Water level indicator

What it is: Indicates whether the humidifier shows the amount of water remaining in its tank.

When it matters: A visible level indicator makes it easier to know when the tank needs refilling.

Importance: MEDIUM

Good value: yes

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Design

6.8

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Fill type

What it is: The design mechanism used to add water to the humidifier tank, distinguished primarily between convenient top-fill and inverted bottom-fill designs.

When it matters: Top-fill humidifiers let you pour water directly into the top with a pitcher without carrying a heavy, dripping tank to the tap.

Importance: LOW

top fill

Color

What it is: The primary exterior color of the humidifier.

When it matters: Color matters when you want the humidifier to blend with the room.

Importance: LOW

white

Material

What it is: The primary material used for the humidifier’s exterior housing.

When it matters: Material matters for durability, feel and appearance.

Importance: LOW

plastic

360° nozzle

What it is: Whether the humidifier has a nozzle that rotates through 360° to direct the mist.

When it matters: A rotating nozzle helps redirect mist without moving the humidifier.

Importance: LOW

Good value: yes

Display

What it is: Whether the humidifier has a display for settings and status information.

When it matters: A display makes humidity, mode and timer information easier to check.

Importance: LOW

Good value: yes

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Dreo Smart Humidifier HM311S 4L vs the average humidifier

Why is Dreo Smart Humidifier HM311S 4L better than the average humidifier?

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Wi-Fi control
Dreo Smart Humidifier HM311S 4L supports Wi-Fi control; the average humidifier does not support Wi-Fi control.
What it is: Indicates whether the humidifier connects to Wi-Fi for remote app-based features.
When it matters: Wi-Fi matters if you want to adjust settings or monitor the humidifier away from its controls.
Importance: HIGH
Good value: yes
Dreo Smart Humidifier HM311S 4L supports Wi-Fi control; the average humidifier does not support Wi-Fi control.
Voice control supported
Dreo Smart Humidifier HM311S 4L supports voice control; the average humidifier does not support voice control.
Supports Amazon Alexa and Google Assistant.
What it is: Indicates whether the humidifier can be operated through a compatible voice assistant.
When it matters: Voice control is useful for hands-free adjustment and smart-home routines.
Importance: MEDIUM
Good value: yes
Dreo Smart Humidifier HM311S 4L supports voice control; the average humidifier does not support voice control.
Hygrostat included
Dreo Smart Humidifier HM311S 4L has a hygrostat; the average humidifier has no hygrostat.
What it is: Whether the humidifier can sense room humidity and regulate its output automatically.
When it matters: A hygrostat helps maintain a chosen humidity target without constant manual adjustment or unnecessary operation.
Importance: HIGH
Good value: yes
Dreo Smart Humidifier HM311S 4L has a hygrostat; the average humidifier has no hygrostat.
Dedicated aroma compartment
Dreo Smart Humidifier HM311S 4L includes a dedicated aroma compartment; the average humidifier does not include a dedicated aroma compartment.
Includes dedicated aroma hardware such as a tray, pad, drawer, or compartment.
What it is: Indicates whether the humidifier has a separate compartment for aroma pads or essential oils.
When it matters: A dedicated compartment keeps fragrance media separate from the main water tank.
Importance: LOW
Good value: yes
Dreo Smart Humidifier HM311S 4L includes a dedicated aroma compartment; the average humidifier does not include a dedicated aroma compartment.
12 hours longer runtime
Dreo Smart Humidifier HM311S 4L runs longer on a single fill than the average humidifier (36 hours vs 24 hours).
What it is: The longest stated operating time from one full water tank.
When it matters: Longer runtime means fewer refills during overnight use or extended daily operation.
Importance: HIGH
Good value: At least 24 hours
Dreo Smart Humidifier HM311S 4L runs longer on a single fill than the average humidifier (36 hours vs 24 hours).36 hours vs 24 hours
4.25 cm shallower body
Dreo Smart Humidifier HM311S 4L has a shallower depth than the average humidifier (14 cm vs 18.25 cm).
What it is: The humidifier’s front-to-back depth.
When it matters: A shallower humidifier needs less usable surface depth on a table or shelf.
Importance: MEDIUM
Good value: Up to 20 cm
Dreo Smart Humidifier HM311S 4L has a shallower depth than the average humidifier (14 cm vs 18.25 cm).14 cm vs 18.25 cm
Display included
Dreo Smart Humidifier HM311S 4L has a display; the average humidifier does not have a display.
What it is: Whether the humidifier has a display for settings and status information.
When it matters: A display makes humidity, mode and timer information easier to check.
Importance: LOW
Good value: yes
Dreo Smart Humidifier HM311S 4L has a display; the average humidifier does not have a display.
10 % RH lower target humidity
Dreo Smart Humidifier HM311S 4L supports a lower target humidity setting than the average humidifier (30% RH vs 40% RH).
What it is: The lowest relative-humidity target the user can select.
When it matters: A lower minimum target provides more flexibility in damp climates or rooms where a modest humidity level is preferred.
Importance: LOW
Good value: Up to 30% RH
Dreo Smart Humidifier HM311S 4L supports a lower target humidity setting than the average humidifier (30% RH vs 40% RH).30 % RH vs 40 % RH
Hygrostat included
Dreo Smart Humidifier HM311S 4L has a hygrostat; the average humidifier has no hygrostat.
12 hours longer runtime
Dreo Smart Humidifier HM311S 4L runs longer on a single fill than the average humidifier (36 hours vs 24 hours).
10 % RH lower target humidity
Dreo Smart Humidifier HM311S 4L supports a lower target humidity setting than the average humidifier (30% RH vs 40% RH).
10 % RH higher target humidity
Dreo Smart Humidifier HM311S 4L supports a higher target humidity setting than the average humidifier (90% RH vs 80% RH).
0.65 L larger water tank
Dreo Smart Humidifier HM311S 4L has a larger water tank than the average humidifier (4 L vs 3.35 L).
1.1 dB lower maximum noise
Dreo Smart Humidifier HM311S 4L is quieter at maximum output than the average humidifier (32 dB vs 33.1 dB).
Wi-Fi control
Dreo Smart Humidifier HM311S 4L supports Wi-Fi control; the average humidifier does not support Wi-Fi control.
Voice control supported
Dreo Smart Humidifier HM311S 4L supports voice control; the average humidifier does not support voice control.
Dedicated aroma compartment
Dreo Smart Humidifier HM311S 4L includes a dedicated aroma compartment; the average humidifier does not include a dedicated aroma compartment.
4.25 cm shallower body
Dreo Smart Humidifier HM311S 4L has a shallower depth than the average humidifier (14 cm vs 18.25 cm).
Display included
Dreo Smart Humidifier HM311S 4L has a display; the average humidifier does not have a display.
3.18 cm shorter body
Dreo Smart Humidifier HM311S 4L has a lower profile than the average humidifier (25.8 cm vs 28.98 cm).
4.7% lighter
Dreo Smart Humidifier HM311S 4L is lighter than the average humidifier (1.4 kg vs 1.48 kg).

Why is Dreo Smart Humidifier HM311S 4L worse than the average humidifier?

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3.13 m² less room coverage
Dreo Smart Humidifier HM311S 4L covers smaller rooms than the average humidifier (27.9 m² vs 31 m²).
2 W higher power draw
Dreo Smart Humidifier HM311S 4L draws more power than the average humidifier (26 W vs 24 W).
3.8% lower humidification rate
Dreo Smart Humidifier HM311S 4L delivers a lower humidification rate than the average humidifier (250 ml/h vs 260 ml/h).
8.45 cm wider body
Dreo Smart Humidifier HM311S 4L has a wider body than the average humidifier (28 cm vs 19.555 cm).
No 360° nozzle
Dreo Smart Humidifier HM311S 4L does not have a 360° nozzle; the average humidifier has a 360° nozzle.
8.45 cm wider body
Dreo Smart Humidifier HM311S 4L has a wider body than the average humidifier (28 cm vs 19.555 cm).
What it is: The humidifier’s side-to-side width.
When it matters: A narrower humidifier takes up less space on a bedside table, desk or shelf.
Importance: MEDIUM
Good value: Up to 20 cm
Dreo Smart Humidifier HM311S 4L has a wider body than the average humidifier (28 cm vs 19.555 cm).28 cm vs 19.555 cm
No 360° nozzle
Dreo Smart Humidifier HM311S 4L does not have a 360° nozzle; the average humidifier has a 360° nozzle.
What it is: Whether the humidifier has a nozzle that rotates through 360° to direct the mist.
When it matters: A rotating nozzle helps redirect mist without moving the humidifier.
Importance: LOW
Good value: yes
Dreo Smart Humidifier HM311S 4L does not have a 360° nozzle; the average humidifier has a 360° nozzle.
3.13 m² less room coverage
Dreo Smart Humidifier HM311S 4L covers smaller rooms than the average humidifier (27.9 m² vs 31 m²).
What it is: The largest room floor area the humidifier is recommended to cover.
When it matters: A larger coverage rating is important for open-plan spaces and larger bedrooms or living rooms.
Importance: HIGH
Good value: At least 40 m²
Dreo Smart Humidifier HM311S 4L covers smaller rooms than the average humidifier (27.9 m² vs 31 m²).27.87 m² vs 31 m²
2 W higher power draw
Dreo Smart Humidifier HM311S 4L draws more power than the average humidifier (26 W vs 24 W).
What it is: The humidifier’s maximum rated electrical power draw.
When it matters: Lower power draw can reduce electricity use, especially when the humidifier runs for many hours each day.
Importance: MEDIUM
Good value: Up to 25 W
Dreo Smart Humidifier HM311S 4L draws more power than the average humidifier (26 W vs 24 W).26 W vs 24 W
3.8% lower humidification rate
Dreo Smart Humidifier HM311S 4L delivers a lower humidification rate than the average humidifier (250 ml/h vs 260 ml/h).
What it is: The maximum amount of water the humidifier can release into the air per hour.
When it matters: A higher rate raises room humidity faster and is more useful in dry or larger spaces.
Importance: HIGH
Good value: At least 300 ml/h
Dreo Smart Humidifier HM311S 4L delivers a lower humidification rate than the average humidifier (250 ml/h vs 260 ml/h).250 ml/h vs 260 ml/h
71.4% more expensive
Dreo Smart Humidifier HM311S 4L is more expensive than the average humidifier (£60 vs £35).
Dreo Smart Humidifier HM311S 4L is more expensive than the average humidifier (£60 vs £35).£60 vs £35

Graphic comparison of Dreo Smart Humidifier HM311S 4L and other products in the Humidifiers category

Attribute category

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Third-party reviews

United Kingdom

United States

(Reviews last updated: August 2026)

What customers like about Dreo Smart Humidifier HM311S 4L?

Quiet operation registering as low as 28dB
Generous 4-liter tank capacity requiring fewer refills
Convenient top-fill design reduces spills
Intuitive smart app and voice control integration
Powerful fine mist output that spreads evenly without wetting furniture
Useful ambient light that doubles as a nightlight and displays humidity status
Includes a dedicated essential oil pad for aromatherapy
Easy to clean due to its modular design and wide opening

What customers dislike about Dreo Smart Humidifier HM311S 4L?

Inaccurate built-in humidity readings affect Auto Mode accuracy
Certain functions like light customization and muting panel sounds require using the app
Using tap water can lead to calcium buildup and white dust residue
Mist nozzle direction is somewhat restricted by placement options
Some users report essential oils can degrade or melt the plastic tray over time
Requires ongoing maintenance to prevent rapid mold growth and odor buildup
Occasional reports of connectivity issues with voice assistants like Alexa
Hidden long-term costs due to paid replacement water filters

Expert reviews

cnet.com

23/02/2026

Summary of the review

Best Humidifiers to Keep Your Home Comfortable and Healthy

The CNET review of top humidifiers highlights the Levoit OasisMist, Dreo HM713S, and Blueair InvisibleMist, finding that top models offer powerful moisture output with significant humidity gains, large capacities, and smart app integration. While these devices provide convenience and consistent performance, drawbacks include high energy usage in warm mist modes, potential for spills during bottom-fill tank removal, and often shorter warranties.

cnn.com

01/01/2026

Summary of the review

The best humidifiers of 2026, tried and tested

The CNN Underscored review identifies top-performing humidifiers based on testing, highlighting benefits like powerful moisture output, quiet operation, and smart features such as automatic shut-offs. Common cons noted across models include the necessity for frequent, thorough cleaning to prevent mold, the cost or hassle of replacing filters, and potential safety risks with warm-mist options.

techgearlab.com

19/08/2025

Summary of the review

The Best Humidifiers | Lab Tested & Ranked

The TechGearLab review identifies the Levoit OasisMist 450S Smart as the top humidifier, highlighting its versatile mist settings and app connectivity, while noting that top-performing models like the Levoit LV600S excel in rapid moisture output. While offering advanced features, the reviewed ultrasonic models are generally characterized by high power usage, rapid water consumption necessitating frequent refills, and a requirement for distilled water to prevent mineral dust.

thespruce.com

06/01/2026

Summary of the review

The 11 Best Humidifiers The Spruce Has Tested

The Spruce's testing of the 11 best humidifiers highlights top-performing models like the Levoit Classic Smart (Best Overall) for their quiet operation, smart app connectivity, and efficient mist distribution. While offering superior functionality, some models are marked by drawbacks such as high price points (e.g., Dyson), smaller tank capacities requiring frequent refills, or, in some cases, loud fan operation.

homeandsmart.de

06/12/2024

Summary of the review

Dreo Humidifier Review – Top Ultrasonic Model with App Control?

The home&smart review rates the Dreo Smart Humidifier (HM311S) 88/100 ("Good"), highlighting its effective humidification for rooms up to 27 m², a generous 4-liter top-fill tank, whisper-quiet operation, and a precise app-controlled automated mode. While highly functional, the device demands significant maintenance for cleaning and descaling the ultrasonic mechanism, and the essential oil diffuser offers only a very faint scent.

Video reviews

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