Humidifier: how much electricity it uses, what it costs in Chilean pesos and which to choose

A 23 W ultrasonic humidifier, like the Xiaomi Humidifier 2 Lite sold in Chile, costs about CLP 5.9 per hour with electricity at CLP 255.27 per kWh (CGE's BT1 residential tariff in force since October 1, 2026). Running 8 hours every night, it adds up to about CLP 1,400 a month. A 260 W warm mist humidifier, by contrast, costs about CLP 66 per hour and more than CLP 15,900 a month with the same use: eleven times more for the same job.

The difference lies in how each device turns water into moisture. Ultrasonic models break it into ultra-fine droplets with a vibrating membrane; evaporative models push air through a wet wick with a fan; and steam models boil it with a heating element. Boiling water takes a lot of energy. In this guide we look at how much electricity a humidifier uses by type, what it costs in pesos and which one makes sense in each case.

The power rating is on the device's label and in the retailer's listing, in watts (W). Household ultrasonic units draw around 20 to 50 W; evaporative models with a fan, about 50 to 60 W in the reference models; and warm mist humidifiers or vaporizers, from 200 W to more than 500 W. The table lists models with their stated power.

Listings checked on November 3, 2026. The power shown is the maximum stated by the manufacturer or retailer. Ultrasonic and evaporative models use less at lower settings.

There is a physical reason for the gap. Taking one liter of water from room temperature to steam requires about 0.73 kWh, almost all of it for the change of state. A steam humidifier pays that bill with its heating element. An ultrasonic one only spends energy vibrating the membrane: the droplets then evaporate in the room air, taking a little heat from the surroundings.

The calculation is power in kilowatts times hours of use times the price per kWh. A 23 W ultrasonic unit (0.023 kW) running 8 hours uses 0.18 kWh per night; over 30 nights that is 5.52 kWh, which at CLP 255.27 comes to CLP 1,409.

Energía Futura calculations with electricity at CLP 255.27 per kWh and 30-day months, rounded. They assume maximum power the whole time, so they are a ceiling.

To put it in context: the 62.4 kWh a month used by a 260 W steam humidifier running all night is about one third of the 180 kWh commonly used as the monthly reference consumption of a household. Our article on how much electricity a home in Chile uses each month shows which appliances really move the bill. An ultrasonic unit, by contrast, stays under 4% of that figure.

Each technology has advantages that go beyond power use. This table sums up the main differences.

For most bedrooms, an ultrasonic unit with a humidistat, which switches off on its own when it reaches the chosen humidity, is the cheapest option to run. It is best filled with distilled or filtered water to avoid white dust. If your tap water is very hard, as in much of northern and central Chile, an evaporative model avoids that problem.

Warm mist units make sense in specific cases, such as a winter cold, and for a few hours. Left on all night, every night, they can cost as much as a small electric heater.

The US Environmental Protection Agency (EPA) recommends keeping indoor humidity below 60%, ideally between 30% and 50%, to prevent mold, according to its brief guide to mold, moisture and your home. A humidifier running without control can push a room above that range, fog the windows and encourage mold on walls and curtains.

That is why a hygrometer, an inexpensive humidity meter, or a humidifier with a built-in sensor is worth having. In homes that already suffer from condensation in winter, the problem is the opposite and the right device is a different one: we explain it in our article on how much electricity a dehumidifier uses.

Diffusers and desktop humidifiers

Small aroma diffusers and USB desktop humidifiers are very low-power ultrasonic devices, usually a few watts. Their power use is negligible, but so is their effect: with 200 to 500 ml tanks, they cannot raise the humidity of a whole bedroom. They work for a desk or a bedside table.

Why the air gets so dry in winter

Cold outdoor air holds little water. When it enters the house and is warmed by a heater, it can hold much more vapor, so its relative humidity drops: the same air that was at 70% outside can fall below 30% inside. That is why dry air, tight skin and an irritated throat show up mostly in the heating months, and in rooms with electric heaters or heat pumps, which heat without adding moisture. Unvented gas or kerosene heaters, on the other hand, do release water vapor as they burn fuel.

A 4-liter tank like the Xiaomi Humidifier 2 Lite's, which delivers up to 300 ml per hour, lasts about 13 hours at full output: enough for a whole night with room to spare.

• Use the humidistat or a timer: switching off at 45% or 50% humidity cuts power use and prevents mold.
• Choose the right size: a large unit in a small room runs briefly and on low; a small one in a large room runs nonstop.
• Clean the tank every few days: standing water collects bacteria and scale, and scale reduces the efficiency of the membrane or heating element.
• Replace the wick of evaporative units as the manual says: a clogged wick evaporates less and forces longer running times.
• Close the bedroom door while it runs: otherwise the moisture escapes to the rest of the house.

To work out the cost with your own utility's rate, check the price per kWh in Chile by municipality and utility. With a more expensive kWh, every figure in the tables rises by the same proportion.

And if dust or pollen worries you as well as dry air, the device for that job is an air purifier. Some models combine both functions, but it is worth checking the power use of each one separately.

How many watts does a humidifier use?

Household ultrasonic units use between 20 and 50 W; evaporative models, about 50 to 60 W; and warm mist models, from 200 W to more than 500 W.

How much does a humidifier cost per month?

Running 8 hours every night with electricity at CLP 255.27 per kWh, a 23 W ultrasonic unit costs about CLP 1,400 a month and a 260 W steam unit, about CLP 15,900.

Can a humidifier be left on all night?

Yes, if it has a humidistat or automatic shut-off when the tank runs dry. Without humidity control, use a timer so the room does not go above 50% or 60%.

Which humidifier uses the least electricity?

The ultrasonic type, because it does not heat the water. The evaporative type comes next. The warm mist type is by far the one that uses the most.

How long does the water in a humidifier last?

It depends on the tank and the output. A 4-liter tank delivering 300 ml per hour lasts about 13 hours at full output; on a low setting, considerably longer.