Warm Mist Humidifier vs Cool Mist Humidifier

There are many air humidifiers around and it may be difficult to understand the most essential differences among them. So here you can read about warm mist humidifier vs cool mist humidifier and this might help in understanding what makes them different or similar.

Before describing the differences between warm mist humidifiers from one side and cool mist humidifiers from the other side, it is important to stress that this is not always one against the other. What I mean by this is that there are many models on the market with dual-purpose, so they can produce both warm and cool mist. One great example is shown in the picture:

Levoit Hybrid Ultrasonic Warm and Cool Mist Humidifier LV600HH
Levoit Hybrid Ultrasonic Warm and Cool Mist Humidifier LV600HH.

This is very convenient because you can use such a device throughout the year and use the type of mist that suits you better with respect to the current climate. But as you know, these devices are used to help against allergies and germs and with the variety of symptoms related to this. So you can use either warm or cool mist, dependent on your current health condition.

For example if you have swelling and pain in your nasal channels, you might rather want to have a cool mist. On the other hand, if you have lots of secrets in the channels, you might rather have a warm mist that will make the secret thinner and you can get it out easier. But it is worth adding that by the time the vapor reaches airways in your organs, it may have the same temperature as if this was a cool mist in the first place, so this may not be so important.

Honeywell HWM-705B HWM705B Filter Free Warm Moisture Humidifier.
Honeywell HWM-705B HWM705B Filter Free Warm Moisture Humidifier & Essential Oil Diffuser.

The main differences

But let’s rather focus onto the devices that have either one function or another, and see what makes them different.

• So if a humidifier has only a warm mist function, in the simplest designs this may imply that it just boils water, and then the water evaporates in the air around. Now, this can be helped with some extra function as a fan, or with an ultrasonic gadget inside that forces a membrane to rapidly oscillate and to disperse the vapor in the air. But such extras in principle are not necessary.

• In the case of humidifiers that do not have any sort of heaters, there is no way to create vapor unless they are equipped with a fan or ultrasonic gadget.

So this is the most important difference between the two types of humidifiers; the first type may or may not have such extras, while the second type must have it.

But this basic difference implies a few extra differences:

  • Warm-only mist humidifiers are essentially ultra-quiet because usually there are no mechanical elements that would make noise. So these can be very simple devices and therefore less expensive.
  • Cool-only mist humidifiers are necessarily louder. But here there are differences in this group, so ultrasonic type can be without any extra fan and then this is still a very quiet device as compared to those that only have a fan that is used to disperse the vapor. The term ultrasonic means that it is in the range of mechanical waves that we humans cannot hear. But there is more to this, an ultrasonic type is usually a bit more expensive.
  • Warm-only mist humidifiers kill most of the bacteria that might be present in the water which you use to fill in the water tank. On the other hand, cool-only mist humidifiers may have filters added in order to remove impurities, but many of them are without any filter.
  • Boiling water in warm mist humidifiers implies extra electricity costs. But there is some (lower) electricity cost in the cool mist humidifiers as well, either because of the fan or its ultrasonic device inside.
Pure Enrichment MistAire Ultrasonic Cool Mist Humidifier
Pure Enrichment MistAire Ultrasonic Cool Mist Humidifier.

How about safety?

If you have kids running around, you would rather keep any item with boiling water out of their way. So in this sense, a cool-mist humidifier may be a better choice.

Related to this is also what I mentioned above regarding the bacteria in the water. Cool mist humidifiers can disperse them into the air, this is less probable with a warm-mist humidifier.

Warm-only mist humidifiers: summary


  • Quieter than cool mist options.
  • Usually less expensive.
  • Better for reducing bacteria and germs.
  • More pleasant during chili days.


  • Safety hazard for children around.
  • Higher energy consumption.

Cool-only mist humidifier: summary


  • Safer for kids.
  • Louder.
  • Lower energy consumption.


  • It can disperse germs and bacteria if not distilled water is used.
  • A bit more expensive.

So I hope this text was helpful. No matter which of the two types you choose, these devices will add moisture to the air. This should help in easing respiratory and sinus issues.

If you are still undecided, chose a dual humidifier that combines both warm and cool mist features. You will find them many in our page with air humidifiers. Check also our separate text with best rated cool mist humidifiers without filters. Thank you for reading.

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