Which Robot Vacuums Are Best

Imagine relaxing with a cup of coffee on a Saturday morning as your vacuum runs itself underneath the sofa and media console, gobbling up dust bunnies and furballs 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 off one chore from your to-do list, without having broken a sweat.

Robotic vacuums make that fantasy a reality. But they’re far from perfect; just ask the CR staffer whose robotic vacuum smeared a fallen bagel topped with cream cheese and grape jelly into the carpeting throughout her house.

But they perform well enough to be in 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 Future Market Insights.

What Robotic Vacuums Do Best

Robotic vacuums have a small motor that propels them around on wheels, turning brushes or rollers that kick up debris as suction pulls it into an internal dustbin no bigger than a quart of milk. Some have added features, such as WiFi connectivity, to allow you to operate them remotely.

Newer robotic vacuums can map rooms by themselves and will send that information to the manufacturer's servers as well as an app on your smartphone. You can then decide which mapped rooms the robovac should clean and when. Some will even allow you to have it clean only a section of a room.

Robotic vacuums leave from and return to a docking station that doubles as a battery charger. In our tests, which we conduct in an area of more than 600 square feet with walls and furniture arranged in a typical layout, some vacuums stop cleaning at 40 minutes and others might run for 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 drain the battery faster. “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.” Some models 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.

Making Your Robovac Feel at Home

A robotic vacuum will dutifully clean floors without any assistance from you, 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, 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 have a front bumper, so they're unlikely to 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 that you can run them on upper floors without worrying about them tumbling to 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.

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