Cost
Filter-free vs filtered
This is not a convenience question. Both machines have to deal with the minerals in your water, and the only difference is whether they end up in a wick you buy or in the air you breathe.
By Scooter M. · Published · Updated
We earn a commission if you buy through the links on this page, at no extra cost to you. It does not change what we recommend or the order the picks appear in. Full disclosure. We show a live price when we have one and the words “Check price” when we do not. We never print a number we cannot currently verify.
| # | Product | Best for | Gal/day | Price |
|---|---|---|---|---|
| 1 | No image Levoit Classic 300STop pickA 6-liter tank, a genuinely wide top-fill opening and no filter to buy. Its own numbers describe a 190 sq ft machine, not the 505 sq ft on the box. | A bedroom you refill twice a week | 0.63implied · 187 sq ft | Check price#ad |
| 2 | No image Honeywell HCM350 Germ Free Cool MoistureA break-resistant, dishwasher-safe tank and a wide opening. It is the only unit here designed so the hardest part of ownership is easy. | Cleaning, without qualification | 1.0implied · 296 sq ft | Check price#ad |
| 3 | No image Levoit OasisMist 1000STen liters and a published 100-hour run time, which is four nights of not thinking about it. The coverage claim is still ahead of the arithmetic. | Long stretches between refills | 0.62implied · 185 sq ft | Check price#ad |
| 4 | No image Vornado Evap40Vornado publishes an output figure and a coverage figure, and the two agree. Four gallons a day covers about 1,180 sq ft at our derived rate against a 1,000 sq ft claim. | The only coverage claim here the arithmetic supports | 4.0published · 1,184 sq ft | Check price#ad |
Filter-free is marketed as pure saving: no wick, no replacement, no recurring cost. That is true as far as it goes, and it stops well short of the whole trade. Every humidifier has to do something with the dissolved mineral in your water. A filtered unit captures it in a wick you replace. A filter-free unit sends it into the room.
We earn a commission if you buy through the links on this page, at no extra cost to you. It does not change what we recommend or the order the picks appear in. Full disclosure. We show a live price when we have one and the words “Check price” when we do not. We never print a number we cannot currently verify.
| # | Product | Best for | Gal/day | Price |
|---|---|---|---|---|
| 1 | No image Levoit Classic 300STop pickA 6-liter tank, a genuinely wide top-fill opening and no filter to buy. Its own numbers describe a 190 sq ft machine, not the 505 sq ft on the box. | A bedroom you refill twice a week | 0.63implied · 187 sq ft | Check price#ad |
| 2 | No image Honeywell HCM350 Germ Free Cool MoistureA break-resistant, dishwasher-safe tank and a wide opening. It is the only unit here designed so the hardest part of ownership is easy. | Cleaning, without qualification | 1.0implied · 296 sq ft | Check price#ad |
| 3 | No image Levoit OasisMist 1000STen liters and a published 100-hour run time, which is four nights of not thinking about it. The coverage claim is still ahead of the arithmetic. | Long stretches between refills | 0.62implied · 185 sq ft | Check price#ad |
| 4 | No image Vornado Evap40Vornado publishes an output figure and a coverage figure, and the two agree. Four gallons a day covers about 1,180 sq ft at our derived rate against a 1,000 sq ft claim. | The only coverage claim here the arithmetic supports | 4.0published · 1,184 sq ft | Check price#ad |
What each type actually is
| Filter-free (ultrasonic) | Filtered (evaporative) | |
|---|---|---|
| Mechanism | A disc vibrates water into a fine mist | A fan draws air across a wet wick |
| Where the minerals go | Into the air, then onto your furniture | Into the wick, which you replace |
| Visible mist | Yes | No |
| Can it over-humidify? | Yes - it keeps atomizing regardless | Barely - a wick self-limits as air saturates |
| Noise | Very quiet; under 28 dB is common | It is a fan. Audible. |
| Typical power | 17-30 W | About 30 W |
| Recurring cost | None, unless you buy distilled water | A wick, on an interval usually not published |
The cost comparison, done properly
There are three scenarios and they give three different answers.
Soft water: filter-free wins
Little dissolved mineral means little white dust and little scale. A filter-free unit costs its electricity and nothing else - roughly seven dollars for a season of overnight running on a 26 W machine. A filtered unit costs about the same electricity plus wicks. Filter-free is simply cheaper, and quieter into the bargain.
Hard water, and you accept the dust: filter-free still wins on money
You will be descaling every week or two and wiping white powder off dark surfaces. Neither costs meaningful money. If that genuinely does not bother you, filter-free remains the cheaper machine to own.
Hard water, and you do not accept the dust: filtered wins, decisively
This is where the arithmetic flips, and it is the scenario most people are actually in. Rejecting white dust on a filter-free unit means the EPA's recommendation: low-mineral water such as distilled. That is a purchase, every day, for the whole season.
Set that against a filtered unit running on tap water at no water cost at all, and the comparison is no longer close for anything above bedroom output. The wick bill, whatever it is, is smaller than several hundred gallons of bought water.
The decision table
| Your situation | Buy | Because |
|---|---|---|
| Soft water, bedroom | Filter-free | No dust to speak of, no wick, and it is quieter |
| Soft water, large room | Either | Filter-free is cheaper; evaporative self-limits, which matters at volume |
| Hard water, bedroom, dust tolerated | Filter-free | Low volume, so descaling is the only real chore |
| Hard water, bedroom, dust not tolerated | Filtered | 115 gallons of bought water a season versus a wick |
| Hard water, large room | Filtered | 728 gallons of bought water is not a plan |
| Nobody will remember the schedule | Filtered | A wick with a drying mode is more forgiving than a mineral-caked transducer |
The cost nobody puts in the filter-free column
Demineralization cartridges. Many filter-free units accept a small ion-exchange cartridge in the tank to reduce white dust. It is a consumable with a replacement interval, sold by the same manufacturer, doing a partial version of the job a wick does completely. If you buy a filter-free unit and then buy cartridges for it, you have bought a filtered humidifier with extra steps.
And one thing that is not about money
An evaporative unit cannot easily over-humidify a room. A wick can only give up as much water as the surrounding air will accept, so as a space approaches saturation, output falls away by itself. An ultrasonic unit has no such limit: it will keep atomizing into a room already at 60 percent, which is above the EPA's stated 50 percent ceiling and is how people end up with condensation on cold glass. In a basement or a tightly sealed room, that self-limiting behavior is worth more than the money either way.
The picks, in full
image
Top pick · A bedroom you refill twice a week
Levoit Classic 300S
A 6-liter tank, a genuinely wide top-fill opening and no filter to buy. Its own numbers describe a 190 sq ft machine, not the 505 sq ft on the box.
The interesting number is not 6 liters, it is 60 hours. A 1.58-gallon tank that lasts 60 hours on low is moving 0.63 gallons of water a day, and 0.63 gallons a day is what covers about 187 square feet at the rate we derive from Aprilaire's own published sizing. That is a bedroom. It is not the 505 square feet on the specification table.
Both figures are true and they describe different settings. Levoit publishes the endurance of the quietest setting and the ceiling of the loudest, and never the output that connects them, so a buyer has no way to check the coverage claim. That is not a Levoit problem, it is a category problem, and it is the reason every roundup here shows the implied figure beside the claimed one.
What you are actually buying is the absence of a filter. No wick means no 30-to-60-day replacement cycle and no annual filter bill, and it also means every mineral in your tap water leaves the machine as white dust or stays behind as scale. Run low-mineral water or accept the descaling, which the EPA's own humidifier guidance is blunt about.
What works
- No wick or replacement filter, so the running cost after purchase is water and 26 watts
- 26 W is genuinely low: at the June 2026 US average tariff a full heating season of overnight running is a few dollars
- The top-fill opening is wide enough to get a hand and a brush inside, which is most of what makes a humidifier easy to keep clean
What does not
- The 505 sq ft coverage claim cannot be reconciled with the published tank and run time
- Ultrasonic, so hard water becomes airborne white dust unless you use low-mineral water
- Levoit publishes no gallons-per-day figure at any setting
Skip this ifyour water is hard and you will not commit to distilled. An ultrasonic unit atomizes whatever is dissolved in the tank, and this one has no wick to catch it.
The arithmetic
- Implied output (low mist)
- 0.63 gal/day
- Covers, at 296 sq ft per gal/day
- 187 sq ft
- Maker’s coverage claim
- 505 sq ft
- Output that claim would need
- 1.7 gal/day
Output derived as tank capacity divided by published run time, times 24. Coverage rate derived from Aprilaire’s own published capacity-and-coverage pairs.
Published specification
- Tank
- 1.58 gal / 6 LSource
- Output/day
- not publishedLevoit publishes tank size and low-setting run time, not gallons per day
- Coverage
- 215-505 sq ft / 20-47 m2Levoit's own figure. Its published tank and run time imply roughly 187 sq ft at our derived rate.Source
- Run time
- Up to 60 hOn the low mist settingSource
- Power
- 26 WAC 120 V, 60 HzSource
- Noise
- 30 dB or lessSource
- Filter
- None requiredA water filter sponge is included and descaling pads are sold separately, but there is no wick to replaceSource
- Cleaning
- Top-fill opening, brush includedLevoit's own wording: refill without flipping the tank overSource
image
Pick 2 · Cleaning, without qualification
Honeywell HCM350 Germ Free Cool Moisture
A break-resistant, dishwasher-safe tank and a wide opening. It is the only unit here designed so the hardest part of ownership is easy.
One gallon over 24 hours is one gallon a day, which at our derived rate is about 296 square feet. Honeywell says medium room. Those two statements agree, which is a low bar that most of this category fails to clear.
The reason to buy it is the tank. Dishwasher-safe and break-resistant, with an opening wide enough to actually reach inside, against an EPA instruction to clean every third day. A humidifier you will genuinely clean twice a week beats a larger one you will clean twice a winter, and this is the only unit here whose maker treats that as a design requirement rather than a footnote.
There is one inconsistency worth naming. The specification table on Honeywell's own page says a 1 gallon tank; the feature copy a few hundred pixels above it says 1.1 gallons. It is a small discrepancy and it is on the maker's own page, which is a fair illustration of why we quote the table and say which one we took.
What works
- Dishwasher-safe, break-resistant tank with a wide opening, which is the whole ballgame for maintenance
- The wicking filter captures minerals, so no white dust regardless of your water
- The published tank and run time are consistent with the room size claimed
What does not
- HAC504 wicks are a recurring cost with no interval published on the product page
- One gallon a day is a bedroom, not a floor of a house
- The maker's own page states two different tank capacities
Skip this ifyou need to humidify an open-plan living space. This is a one-room machine and its own figures say so.
The arithmetic
- Implied output (continuous)
- 1.0 gal/day
- Covers, at 296 sq ft per gal/day
- 296 sq ft
Output derived as tank capacity divided by published run time, times 24. Coverage rate derived from Aprilaire’s own published capacity-and-coverage pairs.
Published specification
- Tank
- 1 galHoneywell's own specification table says 1 gallon; the marketing copy on the same page says 1.1. We quote the table.Source
- Output/day
- not publishedTank and run time only
- Coverage
- Medium roomHoneywell publishes a size class rather than a number. Its published tank and run time imply about 1 gallon per day, or roughly 296 sq ft at our derived rate.Source
- Run time
- Up to 24 hSource
- Power
- not published
- Filter
- HAC504 Filter AOne included. Honeywell states its own filters should be used.Source
- Cleaning
- Dishwasher safe, break resistant tank, wide openingHoneywell's own wording. It also states the wicking filter removes impurities from the water, reducing white dust.Source
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Pick 3 · Long stretches between refills
Levoit OasisMist 1000S
Ten liters and a published 100-hour run time, which is four nights of not thinking about it. The coverage claim is still ahead of the arithmetic.
A 10-liter reservoir running 100 hours is 0.62 gallons a day, which is almost exactly the same daily output as the 6-liter Classic 300S. The tower holds more water; it does not move more water. What you are buying is refill interval, and that is a real thing to buy.
For a bedroom, four nights between refills changes the ownership experience more than any spec on the box. It also means four nights of water standing in a tank, which is precisely the condition the EPA warns about. If you take the long refill interval you have to take the cleaning discipline with it.
27.5 watts for a 10-liter unit is efficient, and the sub-28 dB figure is the quietest published number in this set. If a humidifier has ever woken you up, that number is the one to look at.
What works
- 100 hours on low is the longest published run time here by a wide margin
- Under 28 dB published, the quietest figure in this group
- No wick, no filter subscription
What does not
- The 600 sq ft top-end claim is roughly three times what the published tank and run time imply
- A big reservoir left standing is a bacterial risk if the refill interval becomes the cleaning interval
- Ultrasonic: same white-dust exposure as every other unit in this class
Skip this ifyou want a machine you can ignore. The long refill interval tempts you to leave water standing, and standing water is exactly what the EPA tells you to empty and dry every day.
The arithmetic
- Implied output (low mist)
- 0.62 gal/day
- Covers, at 296 sq ft per gal/day
- 185 sq ft
- Maker’s coverage claim
- 600 sq ft
- Output that claim would need
- 2.0 gal/day
Output derived as tank capacity divided by published run time, times 24. Coverage rate derived from Aprilaire’s own published capacity-and-coverage pairs.
Published specification
- Tank
- 2.6 gal / 10 LSource
- Output/day
- not publishedTank and low-setting run time only
- Coverage
- 300-600 sq ft / 27-55 m2Its published tank and run time imply roughly 185 sq ft at our derived rateSource
- Run time
- Up to 100 hOn the low mist settingSource
- Power
- 27.5 WSource
- Noise
- Under 28 dBSource
- Filter
- None requiredSource
- Cleaning
- Tower format, aroma and descaling pads sold separatelySource
image
Pick 4 · The only coverage claim here the arithmetic supports
Vornado Evap40
Vornado publishes an output figure and a coverage figure, and the two agree. Four gallons a day covers about 1,180 sq ft at our derived rate against a 1,000 sq ft claim.
Run the check that fails everywhere else on this page and it passes here. Four gallons a day at 296 square feet per gallon per day is about 1,180 square feet of coverage, against a claim of 1,000. Vornado left itself margin instead of taking it.
It passes because it is evaporative. A wick and a fan can only put as much water into the air as the air will accept, which is why an evaporative unit self-limits near 50% relative humidity and why it cannot produce white dust: the minerals stay in the wick. The EPA's guidance to use low-mineral water exists mainly because ultrasonic and impeller units disperse what is dissolved in the tank, and this design does not.
The cost of that is the wick. Two of them, on a schedule Vornado does not publish, which is the recurring bill an ultrasonic unit does not have. Whether that trade is worth it is arithmetic, and it is worked through in full on our filter-cost page.
What works
- Publishes an output figure, and the coverage claim survives being checked against it
- Evaporative, so it cannot produce white dust and self-limits near a safe humidity
- Five-year warranty, the longest published here
What does not
- Two wicks to replace on an interval Vornado does not publish
- A fan moving air across a wet wick is audible, and no dB figure is published
- No rated wattage published
Skip this ifyou want silence. Every evaporative unit is a fan, and Vornado publishes no noise figure for this one.
The arithmetic
- Published output (continuous on high)
- 4.0 gal/day
- Covers, at 296 sq ft per gal/day
- 1,184 sq ft
- Maker’s coverage claim
- 1,000 sq ft
- Output that claim would need
- 3.4 gal/day
Output as the manufacturer publishes it. Coverage rate derived from Aprilaire’s own published capacity-and-coverage pairs.
Published specification
- Tank
- 4 galSource
- Output/day
- Up to 4 galVornado's wording: up to a 4 gallon water output when operated continuously on highSource
- Coverage
- Up to 1,000 sq ftSupported by its own published output. This is the only unit in the set where that is true.Source
- Run time
- not publishedVornado publishes output instead, which is more useful
- Power
- not published
- Filter
- Two humidifying wicksTwo are supplied, one front and one rear. No replacement interval is published.Source
- Cleaning
- Vornado states easy to clean and operateSource
Questions people actually ask
Are filter-free humidifiers better?
They are cheaper to own if your water is soft or if you can live with white dust. If your water is hard and you object to the dust, the alternative is buying distilled water - 115 gallons a season for a bedroom unit, 728 for a large-room one - and at that point a filtered unit running on tap water is far cheaper.
What is the difference between a filter-free and a filtered humidifier?
Where the minerals in your water end up. A filter-free ultrasonic unit atomizes the water and everything dissolved in it, so the minerals go into the air as white dust. A filtered evaporative unit evaporates water off a wick, and the minerals stay in the wick, which you replace.
Do filter-free humidifiers produce white dust?
Yes, in proportion to your water hardness. The EPA notes that ultrasonic and impeller humidifiers are very efficient at dispersing minerals in tap water into the air, and advises using low-mineral water such as distilled. Evaporative units do not produce it at all.
Is a demineralization cartridge as good as a filter?
No. It reduces white dust rather than eliminating it, and it is itself a consumable with a replacement interval and a cost. A filter-free unit that you keep buying cartridges for is a filtered humidifier with extra steps.
Which type is easier to keep clean?
Roughly equal on the tank, and different on the rest. An ultrasonic unit has a transducer that scales up and needs descaling; an evaporative one has a wick that cannot be cleaned and must be replaced. The units that are genuinely easiest to look after are the ones with wide openings, dishwasher-safe parts and a drying mode, regardless of type.
Sources
Every figure on this page came from one of the documents below, read on the date shown. We do not cite other review sites, forum posts or video reviews as sources of fact.
- US Environmental Protection Agency - Use and Care of Home Humidifiers (relative humidity ceiling, three-day cleaning interval, low-mineral water, microorganism warning)
- Levoit Classic 300S - manufacturer spec page (retrieved September 1, 2026)
- Honeywell HCM350 - manufacturer spec page (retrieved September 1, 2026)
- Vornado Evap40 - manufacturer spec page (retrieved September 1, 2026)
- Levoit OasisMist 1000S - manufacturer spec page (retrieved September 1, 2026)
- US Energy Information Administration - Electric Power Monthly, Table 5.3: average residential price 18.34 cents per kilowatthour, United States, June 2026
Read next
Best filter-free
Best filter-free humidifiers
Filter-free ultrasonic picks, with an honest account of the white-dust trade that comes with having no wick.
Top pick: Levoit Classic 300S · 0.63 gal/day
White dust: your water, made airborne
What white dust is, why only ultrasonic and impeller units produce it, and the three fixes ranked by how well they work.
The type decision
Evaporative vs ultrasonic
The evaporative-versus-ultrasonic decision, settled on white dust and filter cost rather than on mist visibility.
Top pick: Vornado Evap40 · 4.0 gal/day
Found a number that is wrong? Tell us and we will fix it and say so. How we pick shows every formula used on this page.