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How we test vacuum cleaners

By Matthew Knight

Learn more about how we test vacuum cleaners for our vacuum cleaner reviews.

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.

We've tested the latest vacuum cleaners to find out which are really worth their price tag, and which you shouldn't waste your money on. Find out how our in-depth vacuum cleaner tests are conducted, and what makes up the final score for each model.

Jump straight to:

Why our vacuum cleaner tests are different

Many free to access websites review vacuum cleaners using an individual tester to generate scores based on that individuals preferences, or a small number of cursory cleaning tests. 

As well as using an independent panel to conduct our ease of use tests, we also conduct more than 70 individual dust and debris pick up tests in laboratory conditions, before we make our recommendations. Through our independent lab tests, we've uncovered vacuum cleaners that pick up only 30% of the fine dust we challenge them to suck up, while a Best Buy can vacuum up to an impressive 90%. Other important tests like how well the vacuums filters trap the tiny and nasty particles suck up are very expensive to perform, and aren't something you will find in other online reviews.

What are Which? Best Buys and Don't Buys?

Best Buys are given to vacuum cleaners that impress us the most in our tests. Vacuum cleaners that score over 77% get a Best Buy and come with our firm recommendation, although you should still read our reviews to check for any weaknesses that might impact your buying decision. Vacuum cleaners that score less than 45% are Don't Buys. 

  • Best Buy vacuum cleaners These will excel in all of the important areas, like the quality of the filters, how well it sucks up pet hair and how deeply it cleans on carpets and on hard floors. It will also be easy to use according to our independent panel of experts. 
  • Don't Buy vacuum cleaners These will score poorly where it really matters, leave plenty of dust behind in carpets and on hard floors, and they'll spew a lot of the fine dust and allergens that they do manage to pick up, back into the room you're cleaning.

How is the Which? score calculated? 

Each of the assessments described above goes part way to making up a total test score, which is the percentage figure awarded to each vacuum. Certain assessments are more important than others and so carry different weights:

  • 75% cleaning and filtration
  • 20% ease of use
  • 5% noise and energy use

Our key testing criteria

Below are the key testing categories and how we evaluate each one: 

Vacuum cleaning performance 

You can't tell in the shop how well a vacuum actually cleans, which is where our expert tests come in. When testing vacuum cleaners, we let machines do the hard work by attaching them to custom-built test rigs and setting them to work on dust and grime. We run through a series of tests and ask tough questions of each vacuum cleaner to help calculate our final score. These include:

How well will the vacuum clean fine dust from my carpet and hard floors?

For our carpet test, a machine spreads super-fine dust over a carpet and grinds it in. We then strap each vacuum cleaner into the rig, which pulls and pushes it back and forth five times as it sucks up the dust.  


Each vacuum cleaner covers a distance of 288m in this test alone. The rig springs into action again to do a similar job for smooth and creviced wood floors.

A bad vacuum cleaner picks up less than half of the dirt in the carpet, whereas a Best Buy can pick up twice as much.

We conduct the same fine dust pick-up test on carpets, flat laminate floors and also crevices to simulate the gaps you find between floorboards. 

How well will the vacuum suck up larger bits of debris?

But it's not just fine dust that you'll need to clean up at home, which is why we also challenge each vacuum to pick up larger debris. We use a large amount of dry lentils, spilled onto a flat laminate floor, to represent larger bits of dirt and spills in the home, and measure how much each vacuum cleaner can suck up. Some vacuum cleaners will just plough larger debris around in front of them rather than sucking it all into the machine.

Is it able to maintain suction power while the bag or canister fills up?

Our tests have found that suction power can drop off by more than 30% as the vacuum cleaner fills up. 

A powerful vacuum cleaner is no good if its suction diminishes as it gets full. To test this, we set each vacuum to work on our rig again, measuring the suction when bags or canisters are empty, and again when they're filled with dust and debris.

Can the vacuum keep dust and allergens locked inside?

Many vacuum cleaners leak out some of the fine dust they suck up and leave a dusty residue behind, which can exacerbate symptoms for allergy sufferers. To uncover the models that keep fine dust safely locked away inside, we use specialist machinery to test how much dust and fine particles the vacuum cleaners retain.

How quickly does the vacuum cleaner pick up pet hair and longer hair?

To assess each vacuum cleaner's pet hair pick-up, we comb real cat and dog fur into an area of carpet and then time how long each vacuum cleaner takes to pick it up. Poor-scoring models can take more than three minutes, while the best clear it in less than 30 seconds. 

30 seconds - the time it takes a good vacuum cleaner to clean up a big patch of entangled pet hair.

But pets aren't the only culprits when it comes to moulting, as anyone who has ever had to untangle a vacuum brush bar can attest to. That's why, for our longer hair test, we use real human hair (from a salon), distributing it on carpet to reflect a typical home environment. We then rate how speedily each vacuum can suck them all up.

If that wasn't enough, we also test how long it takes each vacuum cleaner to remove fluff from a cushion using the provided upholstery tool.

Vacuum cleaner ease of use 

A great vacuum cleaner is no good if it's a pain to use. This is why we ask a panel of experts to assess just how easy each machine is to use in common scenarios, from vacuuming up and down stairs to moving it across different and uneven surfaces. They also check how easy it is to change and use the attachments and to empty the bag or canister. 

In 2016 we also started testing the push and pull force of vacuum cleaners, to help determine how much effort it takes to clean the whole home.


Some vacuum cleaners are unwieldy, can't easily get into awkward spaces and are heavy, while others are light to manoeuvre on a range of surfaces and around furniture, and have easy-to-use attachments. We award a star rating to each vacuum for ease of use, based on these scenarios.

We also pass judgement on how easy the vacuum cleaner is to maintain, such as the ease of regularly cleaning hair from brush bars and also how easy it is to clean and replace the bags, containers and filters.

Vacuum cleaner noise levels 

You won't be able to tell in the shop just how noisy a model is - that's why we test the sound of each vacuum cleaner in a chamber in our lab. We've found noise levels vary dramatically, from 65 up to 90 decibels - that's the difference between the sound of conversation a metre away to the sound of a busy main road.

We also ask a panel of experts to rate the noise of each vacuum cleaner and penalise models that make an annoying rattling or other irritating sound.

65 - 90 decibelsThe difference in noise levels recorded from vacuum cleaners

Pick the perfect vacuum cleaner with Which? reviews

Whether you live in a house with carpets or hard floors, and dependant on whether you have a busy home with pets and children, or you live in blisful solitude, we can help you pick the perfect vacuum for your home.

Head to our vacuum reviews to find out which models come top, and which ones will be a waste of your money.
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