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Levoit
Levoit Classic300S Ultrasonic Smart Top Fill Humidifier, Large 6L Tank
A quiet ultrasonic cool-mist humidifier with a 6-liter top-fill tank, a humidity sensor with an auto mode and app control. Best with distilled or purified water; tap water can leave white mineral dust.
Updated October 10, 2026
- Listing: 6-liter tank, up to 60 hours run time and coverage up to 505 sq ft (maker figures).
- Manual: auto mode adjusts the mist to keep 40–50% relative humidity; the target can be changed in the VeSync app.
- Manual: will not mist in auto mode when the room is already above 50% humidity.
- Top-fill tank, so you pour water in from above instead of flipping the tank.
- Manual: change the water daily and clean weekly with distilled white vinegar; no parts go in the dishwasher.
- Maker lists a 30 dB noise level and a Sleep Mode that turns off the display and night light.
Good for
Light sleepers who want a quiet, easy-to-fill bedroom humidifier and will use distilled or purified water.
Skip it if
Hard-water homes that will only use tap water, or anyone who wants dishwasher-safe parts.
Our take
On this page
Our verdict
The Classic 300S suits a bedroom where quiet matters and the owner is willing to buy distilled or purified water. Its humidity sensor and auto mode are the real advantage: Levoit's manual says auto mode keeps the room at 40–50% relative humidity by default and stops misting above 50%, which lines up with the EPA's advice not to humidify above 50%. Skip it if you plan to fill it from a hard-water tap; the EPA notes ultrasonic units can put tap-water minerals into the air as white dust. The variant trap: make sure the listing says Classic 300S (the smart, app-controlled version this guide describes), not a similarly named model without the S.
Cleaning and water
Levoit's manual asks for daily water changes, a weekly clean and descaling with 3 US cups (710 mL) of distilled white vinegar left to soak for 15–20 minutes. It says not to use detergents, not to immerse the base and not to put any part in the dishwasher. The EPA recommends cleaning portable humidifiers every third day, which is stricter than Levoit's weekly schedule; following the EPA schedule is the cautious choice. Aim the mist away from bedding and walls and keep the unit off carpet so its air inlet stays clear.
FAQ
Does the Levoit Classic 300S need a filter?
No replacement wick is needed. The manual describes a small water filter in the tank that you rinse during cleaning and can request a replacement for through Levoit support.
Why is there white dust around my humidifier?
That is usually minerals from the water. Levoit recommends purified or distilled water and avoiding water with high mineral content.
Can I set a different target humidity?
Yes. The manual says the auto-mode target can be changed in the VeSync app.
How we researched this
We read the Amazon.com listing on 2026-10-10 and Levoit's US user manual, and compared both with the EPA humidifier guidance. We did not test this humidifier; noise, coverage and run time are Levoit's figures.
