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How we test tumble dryers

By Matt Stevens

Find out how Which? tests tumble dryers to uncover the top models, and warn you about the worst.

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What makes a Best Buy tumble dryer?

You can't tell in the shops which tumble dryers offer quick, quiet, energy efficient drying - and that is where Which? comes in. We tumble dry over 1,500kg of clothes over a year to find the Best Buy tumble dryers that excel in all these key areas.

Watch our video above to see why a Best Buy tumble dryer will make a real, practical difference to you.

Below we explain more about our in-depth expert tests.

Drying time and programs

The best tumble dryers need just 15 minutes to dry 1kg of laundry, and the worst will take 30. So that means the fastest dryers on the market will churn 6kg of wet laundry into dry clothing in an hour and a half; whereas the slowest dryers will take three hours - the time it takes to watch a Lord of the Rings film.

We test four programs, giving a star rating to each to show how quickly they dry your clothes.

Cotton cupboard dry (70% load)* the cotton clothes that come out of the drum should be dry enough to put straight  into the cupboard.

Cotton cupboard dry (partial load) we also record how quickly the cotton cupboard dry program gets through a small 2.5kg load of cotton clothes, which simulates drying a few essentials in a hurry.

Cotton iron dry (70% load)* Clothes that come out of the iron dry setting or program should be left slightly damp, as this will make the garments easier to iron.

Synthetics/Easy-care cupboard dry (program capacity) the maximum capacity for drying synthetic clothing (man-made fibres like polyester) is typically about half the amount of cottons you can dry. Most 7kg capacity dryers, for example, will let you dry either 3kg or 3.5kg of synthetic clothing in one go.

We fill the drum to the tumble dryer's maximum capacity for synthetic laundry and measure how long it takes for the clothes to be dry enough to put away in a cupboard.

*As of 2013, we started filling the drum to 70% of the dryer's full capacity, rather than 100%. This simulates how people use their dryers at home, but means that dryers tested in 2012 and before are not directly comparable to those tested under the current programme.

Tumble dryer energy use and running costs

We test how much energy each tumble dryer uses so we can guide you to the models that are cheapest to run. The star rating we award for energy use looks at how much energy is expelled by each of the four programs listed above.

The most efficient dryers will cost less than £30 to run a year, the least efficient will cost you over £100

Separately, we estimate how much a dryer will cost you to run each year. The most efficient dryers will cost less than £30 to run a year, the least efficient will cost you over £100.

The running cost is based on drying three cotton cupboard-dry loads a week, for a year. As we have moved to 70% loads, running costs for machines tested in 2013 and after will be less than those tested in 2102 and before.

Dryness of clothes

You'd think that all tumble dryers would excel at drying - but that's not the case. Our tests have shown that lots of dryers fail to dry a load evenly, leaving you with some soggy surprises lurking in an otherwise crisp batch of laundry. Other dryers can take hours to finish a load that should take just a fraction of that time. This is why we test dryness and award a star rating to it in our full tumble dryer reviews.

Determining when clothes are ‘dry’ involves weighing them to see how much water they contain before and after the program. We do this three times for each of our four test loads.

Automatic dryers that use a sensor to determine when your clothes are dry are especially susceptible to falling foul of this rating. A bad sensor may stop the drum when the clothes are still damp and need more drying - or alternatively it might over-dry the clothes.

Over-drying means the program could be on longer than it should be, adding more to your energy bills and increasing the risk of clothes being damaged.

We added a star rating for dryness of clothes to our reviews in 2013.

Evenness of drying

Clothes taken out of the drum at the end of a cycle should be evenly dry or damp - so no sopping wet shirts and crispy socks sharing the same drum.

We weigh up to 23 individual items of clothing after the cotton iron dry cycle to determine how evenly the load has dried and award a star rating for evenness of drying.


We study shirts after the synthetic program, grading the creases on the back of the shirt and the button line.

For machines tested in 2013 and after, if a machines gets four stars from us for creasing, it leaves about the same amount of creases as if you'd just taken a garment out of the washing machines and left it to dry naturally.

Tumble dryer noise

We rate the noise of the dryer at the noisiest part of the program. We consider how loud the sound of the motor is and also the noise made by tumbling laundry in the drum. If a machine gets three stars you should be able to hold a conversation near the dryer but with raised voices.

Condenser tumble dryer efficiency

Condenser tumble dryers trap all the moisture taken from your laundry in a water reservoir, or tank. The rest escapes as steam into your home, turning it into a bit of a sauna.

The best machines trap up to 95% of the moisture from your clothes. The worst we've seen will only hold on to 45%, leaving most of the moisture to soak into your home.

95%The best condenser dryers trap almost every bit of moisture removed from clothes in its water tank.

Ease of use

An easy-to-use tumble dryer will make your laundry days smoother and safer. Our usability tests include how easy the instructions are to follow, how clear the program markings are, how easy it is to fill and empty the machine, and how easy the lint filter, water reservoir and heat exchanger are to clean. We carry out 215 checks to get to grips with convenience. Here are some examples:

Loading and unloading - we look for dryers with a large door that requires little strength to open and close, using either a handle, push catch or press button, and which doesn’t swing shut during loading.

Lint filters and water reservoirs - these should be easy to reach from a standing and sitting position and require little force and simple actions to remove and replace.

Control panel - we look for buttons and dials that are clearly marked with self-explanatory captions nearby, are well spaced and have different shapes for different groups of functions. They should protrude from the instruction panel and be easy to grip, and require little force or one-handed and simple actions to activate.

Energy Saver logo

For products that successfully marry Best Buy performance with superb energy efficiency in our in-depth tests, we award the Which? Energy Saver logo.

Our Energy Saver award is only given to Best Buy tumble dryers that fall within the top 20% of the most energy-efficiency dryers on the market.

The Which? Energy Saver logo is a Which? rating and is not in any way endorsed or associated with official EC labelling laws or regulations. For advice on understanding the official EC energy label on products see our guide; energy labels explained.

How we calculate tumble dryer test scores

A good tumble dryer should get clothes dry in an acceptable time - and without sending your electricity bills through the roof.

65%The minimum score required for regular condenser and vented dryers be Best Buys. Energy efficient heat-pump condenser dryers need to score 70%.


Condenser dryers like these should also do a good job of trapping the moisture removed from clothes in the water tank - and not letting it escape the machine as vapour, which may leave your kitchen or laundry room slick with condensation.

Here is how the scores are broken down for condenser and heat-pump tumble dryers:

  • Drying 47.5%
  • Condensation efficiency 10%
  • Energy consumption 20%
  • Ease of use and noise 22.5%

Vented dryers do not condense water, so there is no test for condensation efficiency. This is how we break the score down for vented dryers:

  • Drying 53%
  • Energy consumption 22%
  • Ease of use and noise 25%

Regular condenser and vented dryers need 65% in our tests to be a Best Buy tumble dryer.

More energy efficient heat-pump condenser dryers need to score 70%.


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