Most humidifiers use 20 to 50 watts, which costs roughly $0.02 to $0.05 per day to run

A typical humidifier draws between 20 and 50 watts of power, depending on the model size and whether it runs continuously or cycles on and off. At the average U.S. electricity rate of about $0.12 per kilowatt-hour, running a 30-watt humidifier for eight hours costs around $0.03 per day, or about $1 per month. Larger ultrasonic or warm-mist models can use 50 watts or more, while small personal humidifiers may use as little as 15 watts.

The actual cost depends on three things: the wattage of your specific model, how many hours per day you run it, and your local electricity rate. A humidifier that runs 24 hours will cost roughly three times as much as one that runs eight hours. If you live in a state with higher electricity rates—like California or Massachusetts—your monthly cost will be noticeably higher than someone in a state with lower rates.

Key Takeaways

  • Most humidifiers use 20 to 50 watts, which translates to roughly $1 to $2 per month of electricity cost at average U.S. rates.
  • Warm-mist humidifiers typically use more power than cool-mist models because they heat water, so expect the higher end of the range.
  • Running time matters as much as wattage—a humidifier that runs eight hours per day costs about one-third as much as one running 24 hours.
  • Your local electricity rate varies by state and provider, so check your utility bill to calculate your exact monthly cost.

How to find the wattage of your humidifier

The wattage is printed on the back or bottom of the unit, usually on a label that also lists voltage and amperage. Look for a number followed by "W" or "watts." If you only see amperage (listed as "A" or "amps), multiply that number by the voltage (usually 120 volts in the U.S.) to get watts. For example, a humidifier drawing 0.4 amps at 120 volts uses 48 watts.

If the label is missing or illegible, check the product manual or the manufacturer's website. Search for your model number plus "specifications" or "wattage." Many retailers also list power consumption in the product details section online, even if the physical packaging does not.

Warm-mist versus cool-mist power use

Warm-mist humidifiers heat water before releasing it, so they consume more electricity—typically 30 to 50 watts or higher. The heating element is the power-hungry component. If you run one for eight hours daily, expect roughly $2 to $3 per month in electricity cost.

Cool-mist humidifiers use ultrasonic vibration or evaporation to disperse water without heating, so they draw less power—usually 15 to 30 watts. A small ultrasonic model running eight hours per day might cost only $0.50 to $1 per month. Evaporative models (which use a fan and wick) fall in the middle, around 20 to 40 watts.

If electricity cost is your main concern, a cool-mist ultrasonic model will be the cheapest to operate. The trade-off is that warm-mist units can be better for certain respiratory conditions and work better in very cold, dry climates.

Calculating your monthly and yearly cost

Use this straightforward formula: (Wattage ÷ 1000) × Hours per day × Days per month × Your electricity rate per kilowatt-hour.

Example: A 35-watt humidifier running eight hours per day in a state where electricity costs $0.12 per kilowatt-hour would cost: (35 ÷ 1000) × 8 × 30 × $0.12 = $1.01 per month, or about $12 per year.

To find your electricity rate, check your utility bill. It is usually listed as "price per kWh" or "rate per kilowatt-hour" and typically ranges from $0.10 to $0.20 depending on your location. Once you know your rate, you can plug in your humidifier's wattage and run time to get an exact figure.

Size and runtime affect total electricity use

A large whole-room humidifier running continuously will use far more electricity than a small personal unit that runs only at night. Whole-room models often draw 40 to 60 watts and may run 12 to 24 hours per day, pushing monthly costs to $5 or higher. A small bedroom humidifier might use only 20 watts and run four to eight hours, costing less than $1 per month.

Many humidifiers have an automatic shutoff when the room reaches a target humidity level, which reduces runtime and lowers your bill. If your model has this feature, the actual cost will be lower than if you ran it continuously. Check your manual to see if this setting is available and how to adjust it.

Comparing humidifier operating costs to other appliances

A humidifier is one of the cheaper appliances to run. For perspective, a typical incandescent light bulb uses 60 watts, a laptop uses 50 to 100 watts, and a space heater uses 750 to 1500 watts. Running a space heater for one hour costs roughly what running a humidifier costs for an entire month.

Even if you run a humidifier year-round, the annual electricity cost is usually $12 to $30, which is negligible compared to heating or cooling costs. The main reason to choose a lower-wattage model is not to save money on electricity, but to reduce overall energy consumption if that is a priority for you.

Frequently Asked Questions

Does a humidifier use a lot of electricity?

No. Humidifiers are among the lowest-power household appliances. A typical model uses 20 to 50 watts, which costs $1 to $3 per month to run. For comparison, a space heater uses 10 to 15 times more power. Electricity cost is rarely a reason to avoid using a humidifier.

Is it cheaper to run a humidifier at night only?

Yes. Running a humidifier eight hours per day instead of 24 hours costs roughly one-third as much. If you only need humidity while sleeping, running it at night will cut your monthly bill by about two-thirds compared to continuous operation.

Do humidifiers use more electricity in winter?

Not because of the season itself, but because you may run them longer. Winter air is drier, so you might run your humidifier more hours per day or leave it on continuously. The humidifier itself uses the same wattage year-round; higher winter bills come from increased runtime, not from the appliance working harder.

What is the difference in power use between a small and large humidifier?

A small personal humidifier typically uses 15 to 25 watts, while a large whole-room model uses 40 to 60 watts. Over a month, that difference adds up to roughly $1 to $2 in additional cost. Larger units also tend to run longer because they cover more space, so total monthly cost can be two to three times higher.

Can I reduce a humidifier's electricity use?

Yes. Run it only when needed rather than continuously, use the automatic shutoff feature if your model has one, and choose a cool-mist ultrasonic model over a warm-mist one. You can also use a smaller humidifier in a single room instead of a large unit for the whole house, which cuts both wattage and runtime.