Suction Isn't the Only Thing That Matters When Choosing a Robot Vacuum

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Right before the Consumer Electronics Show (CES) in January, I noticed a trend in robot vacuums. The suction power these robots were reporting were astronomical. Where Pa (suction power is measured in pascals) in 2024 was considered “high” at 8,000 or 10,000, the Ecovacs x8 is 18,000, the Dreame x50 is 20,000, and the Roborock Saros 10 is 22,000. In calls with the marketing reps and engineers of these machines I would routinely ask, “Is there a limit to how much suction is realistically useful?” And on more than one occasion, engineers revealed that the reason Pa levels had gone sky high was primarily because internal studies had revealed suction power was the primary way consumers chose robot vacuums. While I disagree that suction power translates to a good vacuum, I understand why consumers use this basis to choose: What other criteria would be important? 

Suction is only one factor in getting debris off the floor

To understand why suction power isn’t a good determining criteria, you first have to understand how robot vacuums function. Regardless of brand, almost all robots work like a regular vacuum does. On the bottom of the robot are a roller or series of rollers, like a regular vacuum. As the rollers go over debris, the suction from the robot pulls the debris off the rollers and sucks the debris into an internal, bagless chamber. To move debris toward these rollers, most robots have brushes that sweep the debris. In a perfect situation, all debris is picked up by the rollers, suctioned off of them into the chamber, and the floor is left clean. 

On this Roborock Saros, you can see underneath the robot, the sweep at the front of the robot is designed to move debris towards the rollers. This split design roller is meant to help debris move through the rollers without clogging. Credit: Amanda Blum

The reality is that certain types of debris, such as hair, tie up the rollers, which wraps around the roller and can slice the silicone on it. Larger debris, like a receipt or even a small piece of mulch can get stuck in the roller, requiring a human to dislodge it. Debris can also be sucked up but clog the pipe because it gets stuck on the way to the internal chamber. In some of these cases, more suction might help, but how straight a suction tube is designed, or even how big the flapper is on the internal chamber make a difference, too. In truth, the entire design of the system, and all the parts working in concert is what makes a robot vacuum successful (or not). 

Even on this Roborock QRevo, you can see that the rollers occasionally get stuck with debris like floof, despite having high suction power. Credit: Amanda Blum

For instance, while recently testing the Eureka J15, which has over 16,000Pa, I noticed that even though the sweepers were moving debris directly towards the rollers, the debris wasn’t making it up into the roller, so the robot left the debris behind. The Dyson 360 Vis Nav, which has over 20,000Pa, rides so low to the ground that some debris can’t get to the rollers to be affected by the suction and is instead simply pushed around the floor by the robot.  Meanwhile, the original Switchbot K10+ had only 3,000Pa and did a spectacular job grabbing debris off the floor because it rides a little higher, allowing the rollers to access more debris, and the rollers are designed so that debris doesn’t get stuck as often. My favorite robot vacuum and mop of all time, the Roborock MaxV Ultra Vacuum, has only 10,000Pa but is undeterred by any type of debris and gets floors cleaner than any other vacuum I’ve tried. Roborocks have a very effective roller design that doesn’t seem to suffer from getting beat up by debris, and their sweepers are always being redesigned to be more effective at sweeping debris toward the rollers. 

Navigation, AI and the robots size matter, too

It’s not only the rollers, sweeper, and suction that determines how well it will suction debris off the floor—the robot also has to be able to access the space where the debris is. Robots are now getting slimmer so they can slide under more furniture, but they’re generally still 12-13 inch objects trying to squeeze themselves into spaces, and if you have a lot of floor furniture, the robot will have trouble getting between those objects to effectively clean. Robots do best in big, open spaces, with walls that have no toekicks. The AI on board most robots can sometimes identify debris as obstacles, and tell the robot to avoid the debris altogether. (This is a repercussion of a few robot vacuums accidentally rolling over pet waste years ago and smearing it all over a room; now, robots are overly cautious about anything that could be remotely interpreted as such by AI). 

Debris also has to move through the dock

There’s another point where suction matters, though most product listings don’t discuss it: the robot dock. This is where, in most cases these days, the robot will be auto-emptied into a real vacuum bag that has to be changed every few months. The value of the auto empty is infinite; it’s what makes robot vacuums autonomous. If the dock gets clogged, it’s a lot more work to solve than if the robot does. Recently, I’ve seen mentions of docks like the Narwal Freo Z getting redesigned so there’s less turns in the suction pipe that receives the debris in the dock, since that will translate to less clogs.   

Ultimately, there likely isn’t one “best” robot vacuum, but rather the best robot vacuum for your home, since each house is different. For example, if you have a lot of large debris in your home, you would likely want a Roborock, since they handle that type of debris better than most. If your house has a lot of obstacles, you might consider the Switchbot K10+ Pro, which is much smaller than most robots, and can navigate into smaller spaces. If you have high thresholds in your home, a robot that can navigate those thresholds, like the Dreame x50 or the Roborock Saros line would be important. While suction is a factor of robot success, it shouldn’t be the only or determining factor when making a buying decision.

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