Each washer-dryer rated in our washer dryer reviews has been put through a series of independent tests in the Which? test labs.
We wash and dry more than 1,300kg of laundry a year in our rigorous tests so you can be sure the ones we recommend really do live up to their claims.
Our reviews answer your most crucial questions about washer-dryers:
The best washer-dryers will leave your clothes sparkling clean and fresh, while the worst will make you wish you’d never pressed start.
To check how well a washer-dryer removes stains, we place a cloth splattered with chocolate, oil, blood and red wine marks in the drum, along with sheets and other dirty items of clothing.
We fill the drum with a mixed load that simulates the laundry of an everyday user, and test two wash programs three times over to ensure the accuracy of our results.
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.
The best washer-dryers will handle drying your clothes just as well as washing them. Unfortunately, our tests have found that all-too-often washer-dryers are let down by their standard of drying.
We measure how much time it takes to dry six loads of laundry on two program settings, and rate the washer-dryers based on the standard and evenness of their drying.
The cottons loads we test fill the drum to its maximum drying capacity, which is usually a little over half of the total wash capacity – so a 10kg capacity washer-dryer is likely to have a 6kg drying capacity.
As with wash capacity, the drying capacity for synthetics loads is around half that of cottons loads – so a washer-dryer with a 6kg drying capacity will dry a 3kg synthetics load in our tests.
Your time is precious, which is why we record how long washer-dryers take to dry your clothes and take the times into account in our overall drying ratings.
Our tests have found huge variations in how quickly washer-dryers can get your clothes dried. The quickest dryers can take as little as 25 minutes per kilo, and the slowest as much as 82 minutes per kilo – this means that the quickest dryers will take roughly two and a half hours to dry a cottons load, and the slowest could take more than eight hours.
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 both how well-dried the clothes are, as well as how even the drying is.
However effective your washer-dryer may be, it will still let you down if it's prone to developing faults or breaking down.
To find out which brands are the most reliable, we survey thousands of washer-dryer owners every year about any faults or breakdowns they've experienced, and we use this data to calculate reliability ratings for each of the major brands. The higher the reliability rating, the more reliable that brand has proven to be, according to the experiences of owners.
A washer-dryer can only qualify as a Best Buy we recommend if, as well as the machine doing a great job, the brand scores at least three out of five stars for reliability, from our annual survey of owners. Alternatively, a product can also be a Best Buy if it does not score highly for reliability but instead has a free five-year warranty as standard.
We evaluate every machine's design and controls to assess how easy it is to use. Examples of some features our experts look for are listed below:
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 due to their dual functions, so we measure exactly how much water and energy each washer-dryer uses at the Which? test lab. The lower the amount of energy a washer-dryer uses, the lower your energy bills.
We use our analysis to calculate estimates of how much each washer-dryer will add to your energy bills each year, so you can compare models on running costs as well as the purchase price. To help you know whether the energy costs are high or low for the product, we also provide an energy-efficiency star rating in our reviews.
The chart below shows the highest and lowest yearly running costs we have measured in our tests for washer-dryers.
Based on all washer-dryer reviews currently live on which.co.uk and correct as of February 2020.
We also measure how much noise the machine makes, since there's no way for you to tell this in the shop.
Some washer-dryers are so quiet you'd hardly know they're running, while others are so loud you'll need to move your conversation to the next room.
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 alkaline level, the poorer the machine is at rinsing.
Our in-depth washer-dryer tests assess everything from how clean they get your clothes to how much energy they guzzle and how easy (or not) they are to use. But because cleaning and drying power are so crucial, 65% of the overall test score we award to each washer-dryer is centred on these key functions. Below we reveal the full breakdown of how we weight washer-dryer test scores.
Washer-dryers have to achieve a score of 65% or more to earn our Best Buy recommendation. Washer-dryers that score 45% or less are marked as Don't Buy models we think you should avoid.