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How we test hair dryers

By Jane Darling

Find out more about our market-leading hair dryer tests, and how we find the best hair dryers that are easy to use, lightweight and quick at drying.

Put us to the test

Our Test Labs compare features and prices on a range of products. Try Which? to unlock our reviews. You'll instantly be able to compare our test scores, so you can make sure you don't get stuck with a Don't Buy.

Only the best hair dryers in our tests are awarded our Best Buy recommendation. Best Buy hair dryers dry your hair speedily and are easy to use, while the worst models will leave you nothing short of frustrated. This page explains how we go about identifying the star stylers for you.

You'll want a hair dryer that will deliver on your preferred way of drying your hair. That's why we test hair dryers on both speedy and gentle drying, using high and low settings respectively. We also test the cool shot to see whether it'll be any good at helping you set your hairstyle.

We also record the noise levels, weight and build quality of each hair dryer. Next, we ask a panel of 22 hair dryer users to test them out and give their opinion on how simple each one is to use, whether it's irritatingly noisy and how easy it is to get the results they want.

By combining lab and user trial results, we can bring you the answers to the most important questions about hair dryers:

  • How easy is to use?
  • How quick is it?
  • How heavy is it?
  • Is noisy is it?
  • How effective is it for styling?
  • Should I buy it?

Head to our hair dryer reviews to discover the best and worst models.

Read on to learn more about how we test to get the answers to these questions.

How easy is the hair dryer to use?

The best hair dryers will be a pleasure to use, while the worst will turn hair drying into a chore. To test what each hair dryer is like in practice, we ask our user panel to try them out and make 13 ease-of-use assessments per hair dryer. 

These include whether the handle is comfortable to hold, how easy the markings are to understand and how straightforward the air speed and temperature controls are to use. 

We also get the panel's opinion on special features that entice on the packaging, such as turbo, cool shot and ionic settings. They also comment on whether it's possible to activate these accidentally – which might spell disaster for a fancy hairdo.

Finally, we ask our users to comment on any problems with attaching and removing common accessories, such as the concentrator nozzle or diffuser.

How quick is it?

The best hair dryers can give a fast blast, but also dry gently

The best hair dryers are quick to use. To measure how fast each model is, we record the air temperature generated by each model at 15cm away from the nozzle at all the temperature settings it has. We also record the air speed 15cm from the hair dryer nozzle at each of the air speed settings available.

We test how quickly each hair dryer dries a moistened cloth using maximum heat and air-speed settings. If all you're after is a quick, hot blast to dry your hair, look for a hair dryer that excels at this test. 

However, we also test the hair dryer at minimum heat and air-speed settings, to see how gently you can set it if you want to dry your hair slowly and carefully while doing some styling. The best hair dryers will be capable of both these tasks.

How heavy is it?

The actual weight of a hair dryer doesn't always reflect how heavy it feels when you use it. If a hair dryer is poorly balanced, it can give the impression of weighing a whole lot more.

We ask our panel of users to assess what each hair dryer feels like, both with and without its attachments. If your hair is long and thick, it's likely that you'll find your arm aching before your hair is completely dry if you use a poorly balanced or heavy hair dryer.

Is the hair dryer noisy?

To record exactly how noisy each hair dryer is in decibels, we place them in an anechoic chamber. This is designed to prevent the reflection of sound waves (echo) and is also insulated from external noise. 

Alongside this, we also ask three expert assessors to comment on whether the hair dryer comes across as overly loud, unusually quiet or somewhere in between.

Below shows one of the walls of an anechoic chamber where we measure how much noise each hair dryer makes.

How effective is the hair dryer for styling?

In our lab, we test how versatile each hair dryer is. We check the lowest and highest temperature it produces, and the range of air-speeds possible. Cool hair holds its shape better, and some hair dryers have a 'cool shot' function for this purpose. We put this to the test, recording how quickly the temperature drops when the cool shot is activated.

In the user trial, we ask our participants to comment on how easy it is to control air speed, temperature and any styling functions on the hair dryer, such as the cool shot, turbo or ionic function. We also ask them to rate how easy it is to get the style they're after when using attachments - such as a diffuser or concentrator nozzle - and also without them.

Should I buy it?

72%The score a hair dryer needs to earn our Best Buy recommendation

Each of the assessments described above goes part way to making up a total test score, which is the overall percentage figure we award to each hair dryer. 

But certain assessments are more important than others and so carry different weights. You've told us that the most important aspects of a hair dryer are that they should be easy to use and speedy at drying your hair, so a larger proportion of our test score is based on these areas. The score is broken down as follows:

  • 55% lab performance (includes drying speeds and how well the cool shot function works)
  • 35% user trial assessment (includes ease of use, weight and styling ability)
  •  5% build quality
  •  5% noise

 A hair dryer needs to achieve 72% or more in our tests to earn our Best Buy recommendation. Anything that scores 40% or less is highlighted as a Don't Buy and is a model we think you should avoid.

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