If you're thinking about buying a vacuum cleaner, here are some features to consider. (See also Choosing the right model.)

Power

Vacuum cleaners are often promoted on the basis that more watts equals better performance. This is not true. Our tests show no relationship between performance and rated watts. More watts mean more power, but other factors also have a big impact on performance. They include the design of the wand, suction tube and head, and the number and type of filters.

It's the design that counts, not the power. That's not what the salespeople will tell you, of course!

Variable power

Some cleaners let you vary the motor power. This is useful for reducing the suction when cleaning curtains, cushions and the like. It can also be handy on some floors if the head gets hard to move over the surface. Some cleaners have a bleed valve on the wand which achieves the same result.

Adjustable head height

Allows the height of the cleaning head to be adjusted to match the pile height of your carpet.

Swivel head

Some cleaners have a swivelling connection at the point where the hose attaches to the cleaner. This helps mobility and prevents the cleaner catching on corners or tipping over when you're towing it about.

Telescopic wand

Most mid- to high-priced cleaners have a telescopic wand that you can adjust to suit your height and avoid awkward bending. Cheaper cleaners usually have a fixed-length wand that will not suit everybody. A telescopic wand also makes for easier stowing when the cleaner is not in use.

Wand storage

Most cleaners have a clip for storing the wand upright while the cleaner is in use or when stowing it away.

Accessories

Most cleaners come with a crevice tool for getting into tight spaces, an upholstery brush and a dusting brush. Some or all of these tools can be stored on the body of most cleaners. The more expensive the model, the more tools you should expect.

Blower outlet

Invaluable if you want to blow up an airbed or inflatable dinghy.

Filters

Modern vacuum cleaners use several filters to clean the air they suck in. A HEPA (also known in Europe as an S-class) filter is often used for the final exhaust, trapping 99.97 percent of particle emissions down to 0.3 microns in size. That's small enough to remove cigarette smoke and bacteria. See Asthma and allergens for more about filters.

Weight

Choose a model with a weight that you can manage easily. This is especially important if you have to carry your cleaner up and down stairs, or if you have back problems or a disability.

Noise

Listen to the tone of your preferred cleaner in the shop before you buy it. All cleaners are noisy, but some have a high-pitched noise that many people find extremely irritating.

For disabled users

Items to check are the reach, weight, comfort of the carrying handle and ease of changing the dust bag and filters.

The on/off switch and cord retractor should be easy to operate and the head should not be difficult to move over the floor surface.