Hair dryer heat and speed settings explained

Heat versus speed

Heat is the temperature of the air leaving the dryer. More heat evaporates water faster but also exposes hair to more thermal stress. Speed is the volume and velocity of air. Faster air carries moisture away and is what does most of the drying on modern high-speed dryers.

That is why premium dryers often feel less hot than old supermarket models but dry just as quickly. Their brushless motors push a lot of air, so they need less heat to get the job done. Our article on hair dryer wattage explains how motor design and heater power combine.

What the cold shot button does

The cold shot switches off the heater while the motor keeps running, so you get a blast of cool air. Hair holds its shape as it cools, so cooling a curl or a smoothed section straight after heating it helps the style last longer. A burst of cool air at the end also helps the finish look smoother.

On most dryers you hold the button down; on some you press once to lock it on. A few models, such as the Dyson Airwrap Origin, list a constant cold setting as one of the heat options. Multi-stylers like the Shark FlexStyle IonCurl add a button that releases a burst of cool air with a single tap.

1. 1

   Dry or style a section with warm air.

2. 2

   Keep the brush or curler in place.

3. 3

   Press the cold shot for a few seconds until the section feels cool.

4. 4

   Release the section and move on.

How digital dryers control temperature

Older dryers simply switch the heating element between fixed levels. Many premium dryers instead measure the temperature of the air leaving the outlet and adjust the heater in real time. Dyson says its Supersonic Origin uses a glass bead thermistor that measures exit temperature 40 times a second. Shark says the FlexStyle measures heat 1,000 times a second, and Laifen says its Swift Special checks 100 times a second.

The goal is to keep the air at a consistent temperature rather than letting it spike. Some dryers go further: Dyson says the Supersonic Nural's scalp protect mode targets 55°C at the scalp, using a sensor to judge distance. Laifen lists its hot setting at 176°F and warm at 122°F, which is about 80°C and 50°C.

Choosing settings for your hair type

Fine hair dries quickly and is easy to over-heat, so start with low or medium heat and a moderate speed. Thick or long hair benefits from high speed and medium heat for the rough-dry, with short bursts of high heat for the lengths. Curly hair usually does best on low speed with a diffuser to avoid disturbing the curl pattern.

Our guides to the best hair dryers for fine hair, thick hair and curly hair recommend dryers with the right range of settings for each.

Dryers with gentle settings →

Can you dry hair without heat?

Yes, but it takes longer. High-speed dryers can make cool-air drying more practical than it used to be, because the airflow does a lot of the work. Some people use cool or low heat for most of the drying and add warmth only for styling.

Air stylers such as the Airwrap and FlexStyle also have a cool setting, but curls form best when hair is warmed and then cooled. Our guide on using the Airwrap on wet or dry hair explains how moisture affects styling. Using lower heat settings also reduces the energy each blow-dry uses; see how much electricity a hair dryer uses.

Hot air brushes and the cool shot

Hot air brushes and multi-stylers use the same principles. Heat softens the hair so it takes the shape of the barrel or brush, and cool air locks it in. Many have a cool shot or a constant cool mode for this reason, so check for one when buying.

For more on these tools, see our guide to how to use a hot air brush and our roundup of the best Airwrap-style multi-stylers.

Frequently asked questions

Which heat setting should I use on my hair dryer? Medium heat with high speed suits most rough-drying. Use lower heat for fine hair and styling, and save the highest heat for short bursts on thick hair.

What is the cool shot button for? It turns off the heater so the dryer blows cool air. Cooling a section after styling helps it hold its shape and gives a smoother finish.

Is a hair dryer without heat any good? Cool air will dry hair, just more slowly. A high-speed dryer makes it more practical, but most people use some warmth to style.

Do digital dryers stop hair overheating? They measure the air temperature and adjust the heater to avoid spikes. You still need to keep the dryer moving and use sensible settings.