Washer-dryers: How we test washer dryers
Which? tests how well each washer-dryer washes a range of nasty substances, then sets out to see how well they dry.
Our tests show that washer-dryers wash as well as most washing machines but can't dry as well as tumble dryers. If you tumble dry regularly, buying separates may be a better bet.
To check how well a machine removes stains, we place a cloth with chocolate, oil, blood and red wine marks in the drum along with sheets and other items of clothing.
After the wash we measure how much light is reflected off the cloth using a machine called a spectrophotometer, which measures the intensity of reflected light.
The more light reflected, the better the machine is at removing stains.
Drying time and evenness
We measure how much time and energy it takes to dry a load and rate machines based on their running costs.
Determining when clothes are ‘dry’ involves weighing them to see how much water they contain before and after the program.
We weigh individual items of clothing to work out how much water each contains. This can vary from 3% for a sheet to more than 20% for a pair of jeans or a towel.
The variation between the different items tells us how evenly the load has dried.
Detergent can be irritating to those with sensitive skin.
To measure how well washer-dryers remove it during the rinsing cycle, we take freshly rinsed washing from the machine, just before the spin cycle, and spin it in a super-fast spin dryer.
This dryer spins at 2,800rpm, roughly twice as fast as a typical washing machine.
After the spin, we collect water from the clothes and measure how alkaline it is compared with tap water.
Detergent is very alkaline, so the greater the increase, the poorer the machine is at rinsing.
Ease of use
We prefer large and bright lights, accompanied by a clearly marked and self-explanatory label, which are visible from standing and sitting positions.
Loading and removing washing
We look for a big drum and a large door with wide porthole that opens to 180 degrees and can be loaded easily from a standing or sitting position.
This should be easy to open and close, with no sharp edges. It should require little force and dexterity to remove and replace the detergent dispenser for cleaning.
Buttons and dials
We look for clearly marked, well-spaced protruding buttons and dials, with descriptions that are self explanatory and easy to read. They should also be easy to grip and turn or activate.
Different sizes, textures and shapes, as well as noises that indicate a button has been successfully selected are helpful to people with visual impairments.
Washer-dryers can be far from cheap to run, so we test energy efficiency and water use extensively in our labs. The lower the amount of energy a washer-dryer uses, the lower your energy bills. Our washer-dryer energy energy costs tool shows you exactly how much each washer-dryer uses in pounds and pence to give you the inside track on how much washer-dryers will cost you over their lifetime.
Any products that successfully marry Best Buy performance with superb energy efficiency in our in-depth tests, are eligible to be awarded the Which? Energy Saver logo.
Our Energy Saver award is given to Best Buy washer-dryers that meet our own energy-efficiency criteria and is designed to help you choose products that use less electricity compared to other products of the same type that we've tested.
For washer-dryers, we test for energy efficiency on the washing and drying cycles then rank the results and award the Energy Saver logo only to Best Buys whose energy use is in the top 20% of all the models we've tested.
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.
Which? washer-dryers test results
Some washer-dryers in our online review have a note showing that they were tested before 2011. Since then we’ve changed the way we test washer-dryers to better reflect how they're used at home.
Instead of packing the drum to maximum capacity, which is hard to do under normal domestic conditions, we now use a load that's 80% of the stated maximum capacity. This is a more accurate reflection of how washer-dryers are used at home.
Though you can generally compare older results with the latest washer-dryer test results, they don’t directly correspond. However, each score still gives a very good indication of the washer-dryer's overall performance.