Levoit OasisMist 450S Smart Humidifier

Levoit OasisMist 450S Smart Humidifier

By Levoit · Humidifiers · Home & Workspace

  • 4.5L top-fill tank, warm and cool mist
  • VeSync app control, runs up to 45 hours
  • Raised room humidity to 59% in one hour in testing
  • Aromatherapy tray

Lowest price seen
~$76.00 (approx.)
from $76.00 at Amazon

Prices are snapshots. Check the current price with the store.

Summary

A dual-technology warm and cool mist humidifier with a 4.5 L top-fill tank and VeSync app control, built for medium rooms. Check your water and your electricity budget first: hard tap water causes white dust, and warm mist draws up to 280 W.

Strengths

  • Fast, powerful humidification; independent tests place it among the strongest units in its class.
  • Warm and cool mist let one machine cover winter and summer.
  • Top-fill tank makes refilling simple.
  • Quiet on low settings, rated under 26 dB.
  • VeSync app adds scheduling, remote control and plant-care features.
  • 2-year warranty and replacement pads sold by Levoit.

Weaknesses

  • Warm mist draws up to 280 W and can cost around $175 a year in continuous use.
  • The 4.5 L tank drains in under 20 hours with both modes running.
  • Hard tap water causes white dust; distilled or purified water is recommended.
  • Two systems mean more parts to clean, around 10-15 minutes a session.
  • Owners report water leaking from the base, sometimes damaging furniture.
  • Some owners report inaccurate humidity sensor readings in auto mode.

Verified specifications

ModelLUH-O451S-WUS.
Power120 V, 60 Hz; 280 W maximum in warm mist mode.
Tank capacity4.5 L (1.19 gal).
Cool mist outputup to 300 mL/h.
Warm mist outputup to 550 mL/h.
Runtimeup to 45 hours on the lowest cool mist setting (manufacturer claim).
Noiseunder 26 dB on low cool mist; under 41 dB on high warm mist.
Effective range215–430 ft² (20–40 m²).
Dimensions10.8 × 6.0 × 11.97 in (27.4 × 15.2 × 30.4 cm).
Weight5.3 lb (2.4 kg).
Humidistatbuilt-in sensor with auto mode.
AppVeSync over 2.4 GHz Wi-Fi, with Alexa and Google Assistant voice control.
Designdual 360° rotating nozzles, top-fill tank, touch panel with digital display, memory function.
Modeswarm steam boiler and ultrasonic cool mist, sleep mode (cool mist only, display off), auto shut-off when the tank is empty.
Aromatherapyaroma pad tray, pads included.
In the boxhumidifier, cleaning brush, 3 aroma pads (1 pre-installed), 3 absorption pads (1 pre-installed), 2 water filter sponges (1 pre-installed), user manual and quick start guide.
Warranty2 years.
Full research notes and sources

Output, runtime and coverage

Independent testers agree the OasisMist 450S humidifies fast. Consumer Reports measured 1.9 gallons a day and rated it excellent for performance. AirPurifierFirst raised relative humidity from 40.3% to 57.2% in 60 minutes in a 194 ft² room, a gain of 16.9 points, and took 11 minutes to move humidity up 5 points. TechGearLab watched a room climb from 40% to nearly 60% in an hour.

Runtime is where the marketing and the lab split. Levoit claims up to 45 hours, but that figure only holds on the lowest cool mist setting. AirPurifierFirst measured about 14.9 hours at maximum speed, and TechGearLab saw the tank empty in under 20 hours with both modes running, though cool-only lasted over 31 hours. The 430 ft² coverage rating is a ceiling; MistRanker’s winter-load math puts realistic holding around 155 ft². Noise is rated under 26 dB on low cool mist and under 41 dB on high warm mist, while TechGearLab measured an average of 43 dB during operation.

Warm mist and running costs

Warm mist is the reason to pick this model over a plain ultrasonic unit, and the reason it costs more to run. Levoit rates the boiler at 280 W; AirPurifierFirst measured 279.4 W on maximum warm mist against 27.4 W on maximum cool mist, with an efficiency of 11.0 mL/Wh. The boiler takes several minutes to heat from a cold fill.

Electricity estimates depend on use. Consumer Reports put overnight use at about $1.06 a month, while TechGearLab estimated roughly $175 a year running continuously over three months, a figure MistRanker frames as leaving a space heater on. Distilled or purified water is recommended to avoid white dust, which adds its own recurring cost in hard-water areas, and Levoit sells descaling pads (10-pack) that last 2-4 weeks each depending on hardness.

Cleaning, water and maintenance

Levoit’s manual asks for fresh water daily, a tank and base clean every 3 days, and a periodic descale with distilled white vinegar (3 US cups / 710 mL, soak 15-20 minutes). Aroma and absorption pads need replacing when they stiffen, and no part should go in a dishwasher or the base be immersed. Two systems in one body mean more nooks to clean than a simple ultrasonic unit; AirPurifierFirst estimates 10-15 minutes per session. BHG found bacteria on the filter comparable to other models and, at six months, the unit still ran 12+ hours on a fill.

There is no evidence of user-serviceable internal parts such as the pump, transducer or boiler. Levoit’s replacement accessories cover aroma pads, absorption pads, water filter sponges and descaling pads only.

Which model this is

This page covers the Levoit OasisMist 450S, model LUH-O451S-WUS, the US 120 V variant. It has been sold since roughly 2022-2023, and no hardware revisions were found.

The US Amazon listing for this model is ASIN B0B1DQ8KV3.

Is it worth it?

At $79.99 on Levoit’s own store (sale from an $89.99 list, 2026-10-09) the OasisMist 450S is a strong buy for a medium room: the humidification speed, dual modes and app control are hard to match below $100. VeSync lists it at $89.99, TechGearLab cites a $90 list, and BHG found it at $71 at Target and $90 at Home Depot (2024). Above $130 the case weakens, because the running-cost and cleaning burdens stay the same while simpler or evaporative designs get cheaper. Buy it for power and smart features, not for low upkeep.

Sources

Manufacturer:

Independent reviews:

Owner reports:

Parts and stores:

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