Imagine relaxing with a cup of coffee and the paper on a Saturday morning as your vacuum runs itself underneath the sofa and media console, gobbling up dust bunnies and fur balls before moving on to the kitchen, where it nabs crumbs from last night’s dinner. An hour later, it beeps to let you know it has completed its rounds. You triumphantly check one chore off your to-do list without having broken a sweat.

Robotic vacuums can make that fantasy a reality. They’re far from perfect (just ask our staffer whose robovac smeared a forgotten bagel topped with cream cheese and grape jelly into the carpeting throughout her house), but they perform well enough to be the fastest-growing floor-care category. Annual sales are forecast to rise from $1.5 billion in 2016 to $2.5 billion by the end of 2021, according to research by Future Market Insights.

Robotic vacuums are also gaining in popularity with CR subscribers: A recent survey shows that nearly 10 percent of the vacuums respondents purchased since 2016 are robotic—vs. just 1 percent of the models bought in 2010.

What Robotic Vacuums Do Best

Essentially the working end of an ­upright, robotic vacuums are outfitted with two or three wheels and a small motor that propels them around the house and suctions while brushes or rollers sweep debris into an internal dustbin no bigger than a quart of milk. Some have added features, such as WiFi connectivity, to allow you to operate the machines remotely and to increase their effectiveness.

More on Vacuums

Robotic vacuums depart from and return to a docking station that also acts as a battery charger. In our tests, which we conduct in a 12x16-foot space that simulates a furnished room, some vacuums stop cleaning at 14 minutes and others might run for almost 2 hours.

“Robotics are best for uncluttered rooms with bare floors or low-pile rugs,” says Susan Booth, CR’s lead vacuum test engineer. They generally use more power to navigate over thick carpet, Booth explains, which can accelerate the drain on the battery. “The thicker the pile, the more difficulty the robot has and the more battery power it uses—which means it may dock before it has cleaned the entire space,” she says. Some are smart enough to return to where they stopped and finish the job, but none are yet able to “see” whether they have missed a spot or, not surprisingly, climb stairs.


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Making Your Robovac Feel at Home

A robotic vacuum will dutifully clean floors without any assist from its owner, but some prep is still required. Before yours begins its work, you’ll need to secure any loose cords and pick up socks, PB&J sandwiches, or anything else that might get caught in the brush or roller. If you’d like the vacuum to skip an area of your home, such as a playroom, you can close the door to create a physical barrier or rope it off, virtually, with magnetic boundary strips provided by certain manufacturers.

You should also identify areas that the robot won’t be able to pass through. The devices’ exteriors are wrapped in a bumper, so they won’t damage furniture, but be mindful of any tippy décor. If the vac gently bumps against a table or shelf, will any lamps, vases, or stacks of magazines fall?

Though earlier versions of robotic vacuums used to take an occasional tumble down the stairs, most of today’s models come equipped with a so-called cliff sensor, so you can run them on upper floors without worrying about their demise.

Robotic vacuums use various navigation methods. Depending on the manufacturer and model, the bots may move in what looks like a random fashion or in patterns—usually gridlike—that kick in according to certain variables. “Our tests have shown that the various approaches to navigation can be equally effective in terms of cleaning,” Booth says.

One thing to keep in mind: Robotic vacuums use a method such as a low-frequency radio signal or an infrared beam to find the docking station. If a vacuum loses contact with the dock by, say, moving through multiple rooms in a ranch home, it might go AWOL and end up in an open closet or stuck under a bed. Though our tests didn’t reveal too many errors, our engineers did come to work one day to find a model missing. A search party later discovered that the vac had made its way into a lab down the hall.

Great for Touch-Ups

For all the convenience that robotic vacuums offer, our tests show that they can’t match the power of—or clean as thoroughly as—a good old-fashioned upright or canister vacuum. (See our cleaning comparison, below.)

Still, they can perform well enough to earn their place in a home. “Robotic vacuums can be a hassle-free way to maintain your floors daily, removing surface debris between the times you use a full-sized vac for deeper cleaning,” Booth explains. “They could also potentially lessen the amount of time you have to spend running your full-sized vac.” (iRobot, which makes the top-selling Roomba brand, says its robotic vacuums can save owners as much as 110 hours of cleaning a year, or about 2 hours each week.)

Uprights, which are powered by a cord or by a sizable battery, aren’t always easy to maneuver around a dining table or underneath a bed, where robots still have an advantage: The robotic vacuums we’ve tested are about a foot in diameter and range from 3.3 to 5.5 inches tall, allowing them to scoot farther under furniture and reach spots that bulkier uprights can’t.

Can a Robovac Spy on You?

Several robotic vacuums come with smartphone apps. These apps are not necessary to operate the vacs, but they’re useful for scheduling or remotely starting and stopping cleanings, checking a robot’s progress, or viewing maps of the vacuum’s path around your home to see whether it has missed any spots.

In July 2017 privacy advocates took notice when Reuters reported that iRobot CEO Colin Angle said that the mapping information its Roomba robotic vacuums collect might one day be sold to tech companies. Reuters subsequently corrected the article, saying iRobot might share the data free of charge, not sell it.

James Baussmann, the company’s public relations manager for North America, told CR that iRobot won’t be sending its data to third parties, at least for now: “iRobot believes that in the future, this information could provide even more value for our customers by enabling the smart home and the devices within it to work better, but always with their explicit consent.”

iRobot is not alone. Many robotic-vacuum manufacturers are now recording the paths of their appliances and uploading them to a server. You can then view that data via the company’s app on your smartphone.

“Vacuum data isn’t the most sensitive in the world,” says Justin Brookman, CR’s director of consumer privacy and technology policy. “These maps may be rudimentary now, but it seems likely that they’ll continue to improve over time in order to more efficiently clean your home. It would be nice if these companies made affirmative promises not to sell your information.”

If you’re worried about the privacy of your data, don’t use the app when you set up your device. Or if you’re already using the machine, you can turn off the robotic vac’s WiFi. The trade-off? You’ll no longer receive cleaning data, such as maps of the vacuum’s path, or be able to control the vac from your phone.


Cleaning Comparison: Traditional Upright vs. Robotic Vacuum

In our labs, we ran the top-rated Miele Dynamic U1 Cat & Dog upright, $550, and the top-rated Samsung Powerbot SR20H9051 Series robotic vacuum, $1,000 (both shown below), over separate squares of medium-pile carpet, each embedded with 100 grams of talc and sand.

The Miele upright picked up more than half of the debris; the Samsung robovac picked up less than 20 percent, proving that, for deep cleaning, the bot is no match for the traditional model.

The Miele Dynamic U1 Cat & Dog upright and Samsung Powerbot SR20H9051 Series

Editor's Note: This article also appeared in the January 2018 issue of Consumer Reports magazine.

This article was updated on Dec. 1, 2017, to clarify that Reuters corrected, rather than updated, its July 2017 story to reflect that iRobot might "share maps for free with customer consent" instead of "sell maps."