An on/off switch for the rotating brush lets you stop the brush from rotating when using tools or cleaning bare floors. This helps eliminate scattered dirt on bare floors and reduces the risk of injury if the vacuum tips over during use. It also reduces the risk of damaging a carpet or the finish of a bare floor if the vacuum sits in place at the low-height setting.

A switch that's located on the handle or where your foot can activate it is more convenient than one on the body of the vacuum.

Lets you adjust the height of the machine to a carpet's pile height to allow for easy movement and thorough cleaning. Adjustments are automatic on some models, but we prefer the more precise manual control afforded by some models.

This feature reduces the flow of air through the hose, which can be helpful when cleaning upholstery and curtains.

Common in canisters, not uprights, a retractable cord is one you can rewind via a slight tug or a push button.

Some models have a feature alerting the user when the dust bag or container is full, which impairs the vacuum's ability to clean. Some such models that are bagless simply have a clear bin, letting you see when the bin is full. Other models have an electronic indicator.

High-efficiency particulate-air (HEPA) filters provide the highest level of vacuum-cleaner filtration. In our tests, models with a HEPA filter have been very effective at reducing emissions. However, some models that don't have HEPA filters have performed just as well in our emissions tests, and such vacuums may cost less than HEPA models.

Handle folds to minimize storage space.

Denotes whether the model has a disposable waste bag. A growing number of vacuums, particularly upright models, use a container that can be emptied, eliminating the bag. To capture fine-dirt particles, however, these models must use a filter (such as a HEPA filter) that can need regular cleaning, or replacement. Replacement filters tend to be significantly more expensive than bags. While vacuums with bags may also use filters, the bag acts as a pre-filter that helps to keep the fine-dirt filter cleaner, thus extending its performance until cleaning or replacement. Another caveat: Emptying the dustbin and cleaning a filter can be messy, and handling it may expose you to dust and other allergens.

Weight of the vacuum cleaner, to the nearest pound.

The length, in feet, of a model's power cord.

Indicates how much embedded talc and sand a vacuum lifted from a medium-pile carpet.

Shows how well a vacuum picked up sand without dispersing it on bare floors.

Indicates the strength of airflow through the hose.

Our measurement of the quantity of wood-flour particles a vacuum released under two conditions: first, when only the motor was turned on, and second, while vacuuming.

Reflects how easy it is to push, pull, and carry a vacuum.

Reflects how well a vacuum picks up pet hair from medium-pile carpet.

Based on measurements in decibels.