Humidifiers use far less electricity than most household appliances, but the amount varies by type and runtime
A typical humidifier draws between 20 and 300 watts while running, depending on whether it is ultrasonic, evaporative, or steam-based. For context, a microwave uses 600 to 1200 watts, a hair dryer uses 1000 to 1800 watts, and a refrigerator uses 150 to 800 watts continuously. Most humidifiers run intermittently — they cycle on and off as the room reaches your target humidity — so they are not drawing power all day.
If you run a 100-watt humidifier for 8 hours a day, you will use about 0.8 kilowatt-hours per day, or roughly 24 kilowatt-hours per month. At the U.S. average electricity rate of around 14 cents per kilowatt-hour, that costs about $3.36 per month. A larger steam humidifier running 12 hours daily might cost $8 to $12 per month. The actual cost depends on your local electricity rate, how often the unit cycles, and how long you run it each day.
Key Takeaways
- Ultrasonic humidifiers use the least power, typically 20 to 50 watts, because they vibrate water rather than heat it.
- Evaporative humidifiers use 30 to 100 watts and are efficient because they rely on a fan and a wick, not heating elements.
- Steam humidifiers use the most power, 300 to 500 watts, because they boil water and consume electricity continuously while running.
- Monthly cost for a typical humidifier ranges from $2 to $12, depending on type, runtime, and your local electricity rate.
- Humidifiers cycle on and off rather than run constantly, so actual power draw is lower than the wattage rating suggests.
How humidifier type affects power consumption
Ultrasonic humidifiers are the most efficient. They use a piezoelectric element vibrating at ultrasonic frequency to break water into a fine mist. Because there is no heating involved, power draw is minimal — typically 20 to 50 watts. A small ultrasonic unit might cost less than $1 per month to run 8 hours daily.
Evaporative humidifiers use a fan to pull air through a wet wick or filter, allowing water to evaporate naturally. The fan motor draws 30 to 100 watts depending on fan speed and motor size. These are also relatively efficient because they do not heat water. Running one 10 hours daily costs roughly $1.50 to $3 per month.
Steam humidifiers (also called warm mist humidifiers) boil water using a heating element, consuming 300 to 500 watts while actively heating. They also run intermittently, but each heating cycle uses significantly more power than the other types. A steam humidifier running 8 hours daily can cost $5 to $12 per month depending on size and how often it cycles.
What affects how much electricity your humidifier actually draws
The wattage rating on a humidifier is its peak power draw — the maximum it uses while running at full capacity. Most humidifiers do not run continuously. They cycle on and off based on the humidity level you set. If you set the target to 50 percent humidity and the room is already at 45 percent, the humidifier may run only 2 to 3 hours per day even though it is plugged in for 12 hours.
Tank size and refill frequency also matter. Larger tanks hold more water, so the humidifier runs longer before emptying. A 1-gallon tank might run 6 to 8 hours before needing a refill, while a 5-gallon tank could run 24 to 48 hours. The longer runtime means more total electricity use, but spread across more days.
Fan speed on evaporative models and heating intensity on steam models change power draw. Running an evaporative humidifier on low speed uses 30 to 50 watts, while high speed uses 80 to 100 watts. Similarly, steam humidifiers heat faster on high settings, drawing more power per cycle.
Comparing humidifier costs to other household devices
To put humidifier electricity use in perspective, here is what other common devices cost to run monthly at the U.S. average rate of 14 cents per kilowatt-hour:
| Device | Typical Wattage | Daily Use | Monthly Cost |
|---|---|---|---|
| Ultrasonic humidifier | 30 watts | 8 hours | $1.01 |
| Evaporative humidifier | 60 watts | 10 hours | $2.52 |
| Steam humidifier | 400 watts | 8 hours | $8.96 |
| Space heater | 1500 watts | 4 hours | $25.20 |
| Window air conditioner | 1200 watts | 8 hours | $26.88 |
| Dishwasher | 1800 watts | 1 hour per day | $7.56 |
A humidifier is among the lowest-cost appliances to operate. Even a steam humidifier costs less per month than running a space heater for a few hours or a dishwasher once daily.
How to estimate your humidifier's monthly electricity cost
Find the wattage rating on your humidifier's label or in the manual. Multiply the wattage by the number of hours you run it per day, then multiply by 30 to get monthly watt-hours. Divide by 1000 to convert to kilowatt-hours. Then multiply by your local electricity rate per kilowatt-hour.
Example: A 100-watt evaporative humidifier running 10 hours daily uses 100 × 10 × 30 ÷ 1000 = 30 kilowatt-hours per month. At 14 cents per kilowatt-hour, that costs 30 × $0.14 = $4.20 per month.
Your actual electricity rate varies by location and utility provider. Check your most recent electric bill for the rate per kilowatt-hour, or search "[your city] electricity rates" to find your provider's current pricing. Rates in the Northeast and California are typically higher (16 to 22 cents per kilowatt-hour), while rates in the South and Midwest are often lower (10 to 13 cents per kilowatt-hour).
Ways to reduce humidifier electricity use
Choose an ultrasonic or evaporative model if electricity cost matters to you. Both types use one-fifth to one-tenth the power of a steam humidifier. If you already own a steam humidifier, running it on a lower heat setting reduces power draw, though it will take longer to produce mist.
Use a humidistat or hygrometer to avoid running the humidifier longer than necessary. Many modern humidifiers have a built-in humidistat that cycles the unit off once the room reaches your target humidity. If yours does not, a separate hygrometer (around $15 to $30) lets you see the current humidity and turn the unit off manually when it reaches your goal.
Run the humidifier only in the room where you spend the most time, rather than trying to humidify an entire house. A single-room humidifier uses far less electricity than a whole-house system. Close doors to keep humid air contained and prevent the humidifier from working harder to maintain humidity across a larger space.
Frequently Asked Questions
Does a humidifier use more electricity if I leave it running all night?
It depends on the humidity level in your room. If you set the target to 50 percent and the room reaches that level after 4 hours, the humidifier will cycle off and use no power for the remaining 4 hours. If the room is very dry and the humidifier never reaches the target, it will run continuously and use more electricity. Using a humidistat prevents unnecessary runtime.
Is it cheaper to run a humidifier or a dehumidifier?
Dehumidifiers typically use 300 to 700 watts, similar to or higher than steam humidifiers. Both cost roughly $3 to $15 per month depending on type and runtime. Ultrasonic and evaporative humidifiers are cheaper to run than either device. If you need to control humidity, the cheapest option is an ultrasonic humidifier on low speed.
Will a humidifier noticeably increase my electric bill?
No. Even a steam humidifier running 8 hours daily adds less than $10 per month to your bill. An ultrasonic humidifier adds roughly $1 per month. Unless you run multiple humidifiers or use a whole-house system, the impact on your total electricity bill will be negligible.
Do humidifiers use electricity when turned off but plugged in?
Most humidifiers draw minimal power when off — typically less than 1 watt for the power indicator light. This is called phantom load or standby power. Over a month, this costs less than a penny. Unplugging the humidifier when not in use saves this small amount, but the savings are not significant enough to justify the inconvenience for most people.
What is the most energy-efficient humidifier type?
Ultrasonic humidifiers are the most efficient, using 20 to 50 watts. Evaporative humidifiers are a close second at 30 to 100 watts. Both cost $1 to $3 per month to run. Steam humidifiers are the least efficient at 300 to 500 watts, but they are useful if you need warm mist for respiratory comfort.