Cost
Cost per gallon per day
Compare humidifiers on price and you are comparing boxes. Compare them on price per gallon per day of output and the ranking changes, sometimes dramatically.
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 Vornado Evap40Top pickVornado 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 |
| 2 | No image Levoit LV600S HybridWarm and cool mist from a 6-liter tank, and the only Levoit in this set that publishes a maximum output. On warm mist it genuinely covers a floor of a house. | The one unit here that publishes an output figure | 3.5published · 1,033 sq ft | Check price#ad |
| 3 | No image Levoit Superior 6000SSix gallons, evaporative, and a Dry Mode that dries the wicks between runs. The 3,000 sq ft claim needs five times the output its own run time implies. | Mist-free humidification with a drying cycle | 2.0implied · 592 sq ft | Check price#ad |
| 4 | No image Aprilaire Model 700Eighteen gallons a day against a stated 5,300 sq ft, cited to AHRI Guideline F. It is ducted, it needs installing, and it is the only sizing claim here with a standard behind it. | An actual whole house, sized against a standard | 18.0published · 5,328 sq ft | Check price#ad |
Buy a car and you can compare on dollars per horsepower. Buy a heat pump and you can compare on dollars per BTU. Buy a humidifier and the only normalization anyone offers is dollars per liter of tank, which measures a bucket rather than a machine.
The metric that would tell you something is dollars per gallon per day of output, because output is what determines whether the machine can do the job. This page sets that up, and is honest that the dollar half of it is waiting on a live price feed.
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 Vornado Evap40Top pickVornado 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 |
| 2 | No image Levoit LV600S HybridWarm and cool mist from a 6-liter tank, and the only Levoit in this set that publishes a maximum output. On warm mist it genuinely covers a floor of a house. | The one unit here that publishes an output figure | 3.5published · 1,033 sq ft | Check price#ad |
| 3 | No image Levoit Superior 6000SSix gallons, evaporative, and a Dry Mode that dries the wicks between runs. The 3,000 sq ft claim needs five times the output its own run time implies. | Mist-free humidification with a drying cycle | 2.0implied · 592 sq ft | Check price#ad |
| 4 | No image Aprilaire Model 700Eighteen gallons a day against a stated 5,300 sq ft, cited to AHRI Guideline F. It is ducted, it needs installing, and it is the only sizing claim here with a standard behind it. | An actual whole house, sized against a standard | 18.0published · 5,328 sq ft | Check price#ad |
The denominator
The whole exercise depends on having an output figure, which most makers do not publish. Where they do not, we use the figure implied by their own published tank capacity and run time, noting that it describes the lowest setting.
| Unit | Output | Basis | Covers |
|---|---|---|---|
| Aprilaire 700 | 18 gal/day | published | 5,328 sq ft |
| Vornado Evap40 | 4.0 gal/day | published, continuous high | 1,184 sq ft |
| Levoit LV600S | 3.49 gal/day | published, max warm mist | 1,033 sq ft |
| AIRCARE MA1201 | 2.4 gal/day | implied at max run time | 710 sq ft |
| Levoit Superior 6000S | 2.0 gal/day | implied on low fan | 592 sq ft |
| Levoit Classic 160 | 1.44 gal/day | implied at max mist | 426 sq ft |
| Honeywell HCM350 | 1.0 gal/day | implied, continuous | 296 sq ft |
| Levoit OasisMist 450S | 0.63 gal/day | implied on low | 188 sq ft |
| Levoit Classic 300S | 0.63 gal/day | implied on low | 187 sq ft |
| Levoit OasisMist 1000S | 0.62 gal/day | implied on low | 185 sq ft |
| Canopy Large Room | not computable | nothing published | - |
The numerator, and why it is blank
Every price on this site comes from a live data layer refreshed daily against the retailer. In this build that layer is empty: the Amazon Creators API credentials were not present in the environment, so there are no prices, and every buy button currently reads Check price.
We could type prices in from memory. We will not, and it is worth being explicit about why: the entire value of a table normalizing price against capacity is that both numbers are real. A remembered price attached to a carefully derived output figure would make the derivation look like decoration.
What the metric reveals even without prices
Look at the output column on its own. The 10-liter Levoit OasisMist 1000S has four times the reservoir of the 2.5-liter Classic 160 and, on the figures Levoit publishes for each, less than half the daily output at the setting each maker chooses to quote. Whatever the prices are, the value ranking implied by tank size is wrong.
Similarly, the Honeywell HCM350 is one of the smallest tanks here at a single gallon, and its implied output of 1.0 gallon a day beats three units with tanks two to ten times larger. It runs a gallon through a wick in a day rather than eking a gallon out over three.
The caveat that keeps this honest
The implied figures are not maxima. They come from run times that describe the quietest setting, so most of these machines can move more water than the table shows - the makers simply do not say how much more. A comparison built on implied figures is therefore comparing what each maker chose to publish, not what each machine can do.
That is a real limitation and we are not going to hide it. It is also, in a sense, the point: if a maker publishes an output figure you get a fair comparison, and if it does not you get the comparison it left you with. Three makers in our set publish one. Their claims all survive being checked, which is not a coincidence.
How to use it when you are actually buying
- Get your requirement in gallons per day from the sizing chart.
- Shortlist only units whose output - published, or implied from tank and run time - meets it.
- Divide today's price by the output figure for each. Lower is better value.
- Add five years of consumables and electricity from the five-year total, because a cheap machine with an expensive wick is not cheap.
- Then, and only then, look at the features.
The picks, in full
image
Top pick · 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
image
Pick 2 · The one unit here that publishes an output figure
Levoit LV600S Hybrid
Warm and cool mist from a 6-liter tank, and the only Levoit in this set that publishes a maximum output. On warm mist it genuinely covers a floor of a house.
This is the only unit in the portable group whose maker publishes an output rate, and publishing it is worth crediting. 550 mL an hour is 13.2 liters a day, which is 3.49 gallons a day, which covers roughly 1,030 square feet at our derived rate. That is more than its own 753 sq ft claim, so for once the box is conservative.
The catch is the setting. 3.49 gallons a day on maximum warm mist empties a 6-liter tank in about eleven hours and draws 280 watts while it does it. On the lowest setting the same machine moves 0.76 gallons a day and covers about 224 square feet. One box, a four-and-a-half-fold range, and only the two ends published.
280 watts is the number to think about if you plan to run warm mist all winter. Boiling water is not free, and this is the page where that becomes a real line on a bill rather than a footnote.
What works
- Publishes an actual output rate, which almost nobody in this category does
- Warm mist is genuinely useful in a cold room and slightly reduces microbial growth in the tank
- 6 liters with a 753 sq ft claim that its own maximum output can actually support
What does not
- 280 W rated: warm mist all season is a real electricity cost, not a rounding error
- Maximum output empties the tank in about eleven hours
- The gap between lowest and highest setting is roughly 4.5x, and only the two extremes are published
Skip this ifyou want to run it flat out overnight and forget it. At the published maximum it needs refilling before morning.
The arithmetic
- Published output (lowest mist)
- 3.5 gal/day
- Covers, at 296 sq ft per gal/day
- 1,033 sq ft
- Maker’s coverage claim
- 753 sq ft
- Output that claim would need
- 2.5 gal/day
Output as the manufacturer publishes it. Coverage rate derived from Aprilaire’s own published capacity-and-coverage pairs.
Published specification
- Tank
- 1.58 gal / 6 LSource
- Output/day
- 550 mL/h max warm mistLevoit publishes this as an hourly rate. Over 24 hours that is 13.2 L, or 3.49 gallons per day.Source
- Coverage
- 430-753 sq ft / 40-70 m2Source
- Run time
- Up to 50 hOn the lowest mist settingSource
- Power
- 280 WThe heater dominates. Cool mist alone draws far less.Source
- Filter
- Water filter sponge, 2 suppliedA sponge, not a wick. No scheduled replacement interval is published.Source
- Cleaning
- Descaling pads sold separatelySource
image
Pick 3 · Mist-free humidification with a drying cycle
Levoit Superior 6000S
Six gallons, evaporative, and a Dry Mode that dries the wicks between runs. The 3,000 sq ft claim needs five times the output its own run time implies.
Six gallons over 72 hours is two gallons a day, which covers about 590 square feet. The box says 3,000. To actually hold humidity across 3,000 square feet this unit would need to move a little over ten gallons a day, and at that rate its six-gallon reservoir would run dry in about fourteen hours. Both numbers describe the machine; only one describes it at a time, and the maker publishes no figure that reconciles them.
Dry Mode is the genuinely good idea here and it deserves credit. A wet wick sitting in a warm room is the substrate for everything the EPA warns about, and a fan cycle that dries the wicks between runs attacks that problem directly rather than adding an antimicrobial coating and hoping. It also extends wick life, which is the recurring cost.
Thirty watts to move two gallons a day is efficient, and mist-free operation means the minerals stay in the wicks rather than settling on your furniture. If you can live with a coverage claim you should mentally divide by five, this is a well-made machine.
What works
- Dry Mode addresses the real failure mode of evaporative units instead of masking it
- Mist-free, so no white dust whatever your water is like
- 30 W for six gallons of capacity, with noise published at both ends of the range
What does not
- The 3,000 sq ft claim is about five times what the published tank and run time imply
- Four wicks to replace, on an interval Levoit does not publish
- 45 dB at the top of the fan range is audible in a quiet bedroom
Skip this ifyou bought it for the 3,000 sq ft number. Size it at around 600 square feet on the setting whose run time Levoit actually publishes.
The arithmetic
- Implied output (low fan speed)
- 2.0 gal/day
- Covers, at 296 sq ft per gal/day
- 592 sq ft
- Maker’s coverage claim
- 3,000 sq ft
- Output that claim would need
- 10.1 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
- 6 gal / 22.7 LSource
- Output/day
- not published
- Coverage
- 3,000 sq ft / 279 m23,000 sq ft needs about 10.1 gal/day at our derived rate. Its published tank and run time imply 2.0.Source
- Run time
- Up to 72 hOn the low fan speedSource
- Power
- 30 WSource
- Noise
- 28-45 dBSource
- Filter
- Four wick filters, pre-installedReplacements are sold by Levoit as a four-pack. No replacement interval is published.Source
- Cleaning
- Dry ModeLevoit's own wording: low and high fan speeds dry out the elevated wick filters, extending filter lifeSource
image
Pick 4 · An actual whole house, sized against a standard
Aprilaire Model 700
Eighteen gallons a day against a stated 5,300 sq ft, cited to AHRI Guideline F. It is ducted, it needs installing, and it is the only sizing claim here with a standard behind it.
This is the reference point for the whole site. Aprilaire is the only maker in our set that publishes a capacity in gallons per day and a coverage in square feet together, and cites the residential sizing standard as the basis for pairing them. Three of its models do it consistently: 12 gal/day to 3,600 sq ft, 17 to 5,000, and 18 to 5,300. Those three pairs are where our 296 square feet per gallon per day comes from.
Everything else follows from the fact that it drains. There is no reservoir, so there is no standing water, so the pink film and the mold that dominate portable-humidifier ownership simply do not arise. The Water Panel goes once or twice a heating season instead of a wick every 30 to 60 days, which changes the recurring cost by an order of magnitude.
The honest counterweight is that this is not a purchase, it is a project. It mounts in ductwork, it needs a water line and a drain, it needs a humidistat and an outdoor sensor, and unless you are comfortable cutting into a plenum it needs a contractor. Our whole-house cost page works through the break-even against running several portables.
What works
- The only sizing claim in this set with a published standard behind it
- No reservoir, so no standing water and none of the maintenance that follows from it
- Water Panel changed once or twice a season instead of a wick every month or two
What does not
- Requires ducted forced-air heating, a water supply, a drain and, realistically, an installer
- Installed cost is a different order of magnitude from any portable here
- Wastes water: the drain design that keeps it clean also sends water to waste
Skip this ifyou rent, or you heat with anything other than a ducted forced-air system. Neither is a fixable objection.
The arithmetic
- Published output (continuous)
- 18.0 gal/day
- Covers, at 296 sq ft per gal/day
- 5,328 sq ft
- Maker’s coverage claim
- 5,300 sq ft
- Output that claim would need
- 17.9 gal/day
Output as the manufacturer publishes it. Coverage rate derived from Aprilaire’s own published capacity-and-coverage pairs.
Published specification
- Tank
- not publishedThere is no tank. It is plumbed to the water supply and drains to waste.
- Output/day
- 18 gal/daySource
- Coverage
- Up to 5,300 sq ftAprilaire states this for tightly constructed homes and cites AHRI Guideline FSource
- Power
- 24 VAC via the supplied transformerSource
- Filter
- Model 35 Water PanelAprilaire's stated schedule is once or twice per heating season, which is by far the longest interval of any unit hereSource
- Cleaning
- Built-in drain flushes mineral build-upWater does not stand inside the unit, which removes the standing-water problem entirelySource
Questions people actually ask
How do you compare humidifier value?
Divide the price by the daily output in gallons, not by the tank size. Output is what determines whether the machine can hold humidity in your room; a tank only tells you how often you refill. Tank size and output are unrelated - a 10-liter unit in our set has less than half the published-basis output of a 2.5-liter one.
Is a bigger tank better value?
Not necessarily, and often the opposite. The Levoit OasisMist 1000S has four times the reservoir of the Classic 160 and, on the figures each maker publishes, under half the daily output. You are buying refill interval, which is a real thing to buy, but it is not capacity.
Why does this page not show prices?
Because this build's live price layer is empty - the Amazon Creators API credentials were not present in the environment that built the site - and we do not publish prices we cannot currently verify. The output figures are the part that took work; the prices are a thirty-second lookup you can do yourself.
What is a good cost per gallon per day for a humidifier?
We are not going to invent a benchmark. What is useful is the comparison between two specific machines you are actually choosing between, run on today's prices, with five years of consumables added.
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.
- Aprilaire Model 700 - manufacturer spec page (retrieved September 1, 2026)
- Vornado Evap40 - manufacturer spec page (retrieved September 1, 2026)
- Levoit LV600S - manufacturer spec page (retrieved September 1, 2026)
- AIRCARE MA1201 console - manufacturer spec page (retrieved September 1, 2026)
- Levoit Superior 6000S - manufacturer spec page (retrieved September 1, 2026)
- Levoit Classic 160 - manufacturer spec page (retrieved September 1, 2026)
- Honeywell HCM350 - manufacturer spec page (retrieved September 1, 2026)
- Levoit OasisMist 450S - manufacturer spec page (retrieved September 1, 2026)
- Levoit Classic 300S - manufacturer spec page (retrieved September 1, 2026)
- Levoit OasisMist 1000S - manufacturer spec page (retrieved September 1, 2026)
- Canopy Humidifier - manufacturer spec page (retrieved September 1, 2026)
Read next
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A five-year cost-of-ownership framework with the electricity computed, the consumable multipliers derived, and the gaps named rather than filled.
Top pick: Levoit Classic 300S · 0.63 gal/day
Gallons per day: the derivation
The full derivation of the sizing rate, from three published manufacturer capacity-and-coverage pairs, including a plain statement of its limits.
Master roundup
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The master roundup: every unit in our set, with its output computed against its coverage claim and a stated reason to skip it.
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.