Boneco humidifiers
Boneco has 3 units here, from $230 to $400, across 2 types. The most capable is the Boneco U700 at 4 gal/day, enough for 985 sq ft. 3 of the 3 cannot produce white dust.
Across the lineup, Boneco's published room sizes average 0.94× what the output supports — which is to say they match. Very few makers here do. How that is calculated.

Boneco
Boneco U700
Four gallons a day from a tabletop unit, which puts the U700 level with Vornado's Evap40 console on output while taking up a fraction of the floor. Its 1,000 sq ft figure lands within two percent of the load calculation - Boneco and Vornado are the two brands here whose marketing numbers and physics agree. Nine litres is the largest tank of any tabletop unit in the catalog and still only fourteen hours at full tilt, which is the recurring lesson of this category: capability and refill interval trade against each other and no amount of marketing changes it. The self-cleaning mode is genuinely unusual at any price.
985 sq ft supported · box says 1,000 sq ft

Boneco
Boneco U350
Swiss, expensive, and unusually straight about what it does: 3.17 gallons a day published, against a 650 sq ft claim that the load calculation puts at 780. A maker printing a number 17% below what its own output supports is doing something almost nobody else in this catalog does. It pairs a demineralisation cartridge with an Ionic Silver Stick for the water, so the two failure modes of a cheap ultrasonic - dust on the furniture, life in the tank - both have a specific countermeasure. The tank is only 5 litres, which at full output is about ten hours.
781 sq ft supported · box says 650 sq ft

Boneco
Boneco W200 Air Washer
An air washer works by spinning a stack of plastic discs through a water bath: air passes over the wet surfaces, picks up moisture, and drops some dust on the way. The appeal is that there is no wick to buy - ever - because the discs are permanent and go in the dishwasher. Boneco's technical data gives 350 grams an hour, which is 2.22 gallons a day and supports about 547 sq ft, so the 540 on the listing is one of the few coverage claims in this catalog that its own maker's output figure actually backs. The rest of the arithmetic is as plain: a 4.5-litre bath, one silver stick a year, no filters, and about thirteen hours between fills if you are running it at the room it claims.
547 sq ft supported · box says 540 sq ft