How much does it cost to run a humidifier?
Short answer: A humidifier drawing 40 watts costs about $0.01 per hour at the U.S. average residential price of 18.31¢ per kWh. Used 10 hours a day, 30 days a month, that is about $2.20 per month and $26.37 per year. In Louisiana, the cheapest state, the same use costs $1.53 a month; in Hawaii, the most expensive, $5.76.
Humidifier cost calculator
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Hours per day the humidifier is running, typically overnight.
Uses 12.0 kWh per month. The starting price is the U.S. residential average; choose your state or type the price from your own bill.
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| Appliance | Usage | Per month | Remove |
|---|---|---|---|
| Total | |||
| Per year |
Most humidifiers use very little electricity. An ultrasonic or evaporative model draws 30 to 40 watts and costs about two dollars a month to run every night. A warm-mist model, which boils the water, uses several times as much.
Cost by size and setting
Costs below use the U.S. average price and 10 hours a day, 30 days a month.
| Type | Power | Per hour | Per month |
|---|---|---|---|
| Ultrasonic cool mist | 30 W | $0.01 | $1.65 |
| Evaporative | 40 W | $0.01 | $2.20 |
| Warm mist or steam vaporizer | 250 W | $0.05 | $13.73 |
Three types, very different power
An ultrasonic humidifier uses a vibrating plate to turn water into a fine mist. An evaporative one blows air through a wet wick. Both need only a small motor or fan. A warm-mist humidifier, or steam vaporizer, heats water until it boils, and boiling takes a great deal of energy: 250 watts or more.
What changes the cost
Mainly the type, then the output setting and the hours of use. Whole-house humidifiers attached to a furnace use little electricity themselves but add slightly to heating costs, because evaporating water takes heat from the air.
How to lower the cost
- Choose a cool-mist model unless you need warm mist.
- Use the built-in humidistat, or a separate one, and aim for 30 to 50 percent humidity.
- Run it only in occupied rooms.
- Clean it regularly; scale on the element or plate reduces output.
How a humidifier compares with other appliances
Typical power and use for each appliance, at the U.S. average price of 18.31¢ per kWh. Follow a link for that appliance's own calculator, or compare two side by side.
| Appliance | Power | Typical use | Energy per month | Cost per month |
|---|---|---|---|---|
| Humidifier | 40 W | 10 hours a day, 30 days a month | 12.0 kWh | $2.20 |
| Air purifier | 50 W | 24 hours a day, 30 days a month | 36.0 kWh | $6.59 |
| Dehumidifier | 500 W | 12 hours a day, 30 days a month | 180.0 kWh | $32.96 |
| Space heater | 1,500 W | 8 hours a day, 30 days a month | 360.0 kWh | $65.92 |
| Box fan | 75 W | 8 hours a day, 30 days a month | 18.0 kWh | $3.30 |
The math behind the numbers
40 watts ÷ 1,000 = 0.04 kW. 0.04 kW × 10 hours = 0.4 kWh per day. 0.4 kWh × $0.1831 = $0.07 per day. Over 30 days that is 12.0 kWh and $2.20 a month.
Your own figure will differ if your appliance has a different wattage, if you use it more or less, or if your price per kWh is not the national average. Change any of those in the calculator at the top of this page. Our step-by-step guide explains where to find each number.
Cost to run a humidifier in every state
Based on 40 watts for 10 hours a day, 30 days a month, at each state's average residential electricity price for July 2026.
| State | Price per kWh | Per hour | Per month | Per year |
|---|---|---|---|---|
| Alabama | 16.40¢ | $0.01 | $1.97 | $23.62 |
| Alaska | 28.83¢ | $0.01 | $3.46 | $41.52 |
| Arizona | 15.38¢ | $0.01 | $1.85 | $22.15 |
| Arkansas | 14.33¢ | $0.01 | $1.72 | $20.64 |
| California | 33.61¢ | $0.01 | $4.03 | $48.40 |
| Colorado | 17.00¢ | $0.01 | $2.04 | $24.48 |
| Connecticut | 24.16¢ | $0.01 | $2.90 | $34.79 |
| Delaware | 18.48¢ | $0.01 | $2.22 | $26.61 |
| District of Columbia | 25.21¢ | $0.01 | $3.03 | $36.30 |
| Florida | 15.03¢ | $0.01 | $1.80 | $21.64 |
| Georgia | 16.27¢ | $0.01 | $1.95 | $23.43 |
| Hawaii | 48.00¢ | $0.02 | $5.76 | $69.12 |
| Idaho | 13.73¢ | $0.01 | $1.65 | $19.77 |
| Illinois | 19.22¢ | $0.01 | $2.31 | $27.68 |
| Indiana | 16.73¢ | $0.01 | $2.01 | $24.09 |
| Iowa | 15.99¢ | $0.01 | $1.92 | $23.03 |
| Kansas | 15.27¢ | $0.01 | $1.83 | $21.99 |
| Kentucky | 13.81¢ | $0.01 | $1.66 | $19.89 |
| Louisiana | 12.72¢ | $0.01 | $1.53 | $18.32 |
| Maine | 32.41¢ | $0.01 | $3.89 | $46.67 |
| Maryland | 21.41¢ | $0.01 | $2.57 | $30.83 |
| Massachusetts | 30.49¢ | $0.01 | $3.66 | $43.91 |
| Michigan | 23.05¢ | $0.01 | $2.77 | $33.19 |
| Minnesota | 17.45¢ | $0.01 | $2.09 | $25.13 |
| Mississippi | 14.54¢ | $0.01 | $1.74 | $20.94 |
| Missouri | 16.09¢ | $0.01 | $1.93 | $23.17 |
| Montana | 14.99¢ | $0.01 | $1.80 | $21.59 |
| Nebraska | 13.78¢ | $0.01 | $1.65 | $19.84 |
| Nevada | 12.77¢ | $0.01 | $1.53 | $18.39 |
| New Hampshire | 26.60¢ | $0.01 | $3.19 | $38.30 |
| New Jersey | 25.19¢ | $0.01 | $3.02 | $36.27 |
| New Mexico | 16.09¢ | $0.01 | $1.93 | $23.17 |
| New York | 29.90¢ | $0.01 | $3.59 | $43.06 |
| North Carolina | 15.16¢ | $0.01 | $1.82 | $21.83 |
| North Dakota | 13.41¢ | $0.01 | $1.61 | $19.31 |
| Ohio | 19.45¢ | $0.01 | $2.33 | $28.01 |
| Oklahoma | 14.35¢ | $0.01 | $1.72 | $20.66 |
| Oregon | 15.97¢ | $0.01 | $1.92 | $23.00 |
| Pennsylvania | 21.72¢ | $0.01 | $2.61 | $31.28 |
| Rhode Island | 28.29¢ | $0.01 | $3.39 | $40.74 |
| South Carolina | 15.47¢ | $0.01 | $1.86 | $22.28 |
| South Dakota | 15.37¢ | $0.01 | $1.84 | $22.13 |
| Tennessee | 13.71¢ | $0.01 | $1.65 | $19.74 |
| Texas | 15.88¢ | $0.01 | $1.91 | $22.87 |
| Utah | 13.12¢ | $0.01 | $1.57 | $18.89 |
| Vermont | 23.75¢ | $0.01 | $2.85 | $34.20 |
| Virginia | 17.55¢ | $0.01 | $2.11 | $25.27 |
| Washington | 14.71¢ | $0.01 | $1.77 | $21.18 |
| West Virginia | 15.78¢ | $0.01 | $1.89 | $22.72 |
| Wisconsin | 19.06¢ | $0.01 | $2.29 | $27.45 |
| Wyoming | 14.36¢ | $0.01 | $1.72 | $20.68 |
Frequently asked questions
How much does it cost to run a humidifier all night?
About $0.07 for 10 hours at the U.S. average electricity price with a 40-watt cool-mist model.
Do humidifiers use a lot of electricity?
Cool-mist models do not: about $2.20 a month. Warm-mist models use five to eight times as much.
Is a warm-mist or cool-mist humidifier cheaper to run?
Cool mist. It does not have to boil the water.
Sources
- U.S. Energy Information Administration, Electric Power Monthly (state electricity prices)
- U.S. Department of Energy, Energy Saver: Appliances and Electronics
Electricity prices are the EIA figures for July 2026. Wattages are typical values; check the label on your own appliance.