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For the past few years, high-end robot vacuums have been in an arms race of sorts. In 2022, a model with 5,000 pascals (Pa) of suction power was considered top of the line. Since then, premium models have more than quadrupled that stat, currently maxing out at 22,000Pa on the Roborock Saros 10 and the Saros Z70. The idea is simple: The higher the number, the more suction power you can expect.
I’ve been reviewing robot vacuums for years, and suction power is indeed one of the most important factors I consider. But in my testing, I've noticed something interesting: As the number of pascals goes up, I'm not necessarily seeing a correlation in real-world cleaning power. What's the deal? And are pascals worth considering at all? Let's walk through it all together.
What Is a Pascal and What Does It Mean for Robot Vacuums?
A pascal is a mathematical unit of force. One pascal is equal to a pressure of one newton per square meter. Robot vacuum manufacturers commonly use it to quantify the raw suction power of their vacuums. The higher the pascal number, the more force the vacuum can exert on the floor when trying to extract dirt.
On the mid-to-low end of the robot vacuum range, you can find models varying from around 2,000 to 5,500Pa; my current favorite budget model, the $299.99 TP-Link Tapo RV30 Max Plus, has 5,300Pa.
That said, there is no regulated standard for testing pascals in robot vacuum cleaners. That’s not to say that major manufacturers are exaggerating their figures, but it likely points to a lack of consistency from brand to brand, since different companies use slightly different methodologies to gauge the pascals of their machines.
Moreover, at the risk of stating the obvious, pascals aren’t the only determining factor in a vacuum’s pickup performance. The shape of the brush roll plays a big part, both in terms of whether it helps agitate the dirt and allows enough airflow. The vacuum's dimensions also impact performance, particularly in corners and under furniture, since a robot can't clean where it can't fit. Even the wheels and the overall build play a part, as distance from the ground can both change the amount of force applied to the surface and how much airflow can actually be generated in the given distance.
Why Pascal Ratings Are Misleading
I put each robot vacuum I review through a series of stringent trials, including precisely measured cleaning tests. I conduct these tests in two different 100-square-foot rooms, one with carpeting and the other with hardwood. I start with clean flooring, weigh out a specific amount of rice (representing everyday debris particles), spread the rice on the floor, and then let the robot run. I weigh the robot’s dustbin before and after each run to calculate how much of the rice it collected, then I repeat the tests with sand, a much more challenging type of debris to remove. Check out all the details of my testing procedure here.
With each test, I’m looking at different criteria. Rice on carpet, the easiest of my four tests, mostly allows me to check for coverage consistency. With tests on hardwood, I'm checking to see how well the vacuum can clean along walls and in corners, and whether or not it’s prone to flinging or dropping dirt as it works. Sand on carpet is a suction power stress test, and the one where every robot vacuum scores the lowest. It helps me evaluate a robot vacuum's ability to extract stubborn, hard-to-see dirt from tightly packed carpet fibers.
The latter is the test that convinced me the pascal is an overrated stat. Why? Here's an example: The Ecovacs Deebot X2 Omni has 8,000Pa and picked up 45.6% of the sand in this test. Its successor, the Deebot X8 Pro Omni, has 18,000Pa of suction, but only picked up 37.7% of the sand under the same conditions.
That's not to slight Ecovacs in particular. The Dreame X30 Ultra, released around the same time as the Deebot X2 with a similar suction rating (8,300Pa), only picked up 31.4% of the sand in this test. That Dreame model excelled in my hardwood tests, however, so it's not a poorly designed model; it just can't dig stubborn debris out of carpet fibers as well as the X2. In addition, the Eufy Omni E28 only scored a 20.6% on the sand-on-carpet test, despite having more suction power (20,000Pa) than the Deebot X8. Even at the very top of the line as far as pascals, the 22,000Pa Roborock Saros 10 and Saros Z70 picked up 40.7% and 29.1% of the sand, respectively.
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Bear in mind, any individual test has inherent limitations, and my sand-on-carpet gauntlet isn’t meant to tell the whole story, either. For consistency, I run each robot using its smart mode if available to let it determine its own cleaning parameters. If a smart mode isn't available, I run the robot using its default operating mode. I don't turn the suction power up to max, and almost all vacuums would undoubtedly perform better on the test if I did.
However, by conducting the test the way that I do, I allow the vacuum’s smarts to come into play. Ideally, a robot vacuum will sense extra-soiled areas and increase the suction on its own, a capability many are advertised to offer. The idea is to asses how well it will pick up the invisible dirt in your home, since most dust and other debris on the floor is hard to see with the naked eye. If you can't see the mess yourself, you won't think to turn up the suction, so a robot vacuum should be as autonomous as possible.
With these testing parameters, I’m confident that my evaluations are fair and provide comparable data for evaluating real-world robot vacuum pickup performance across brands.
Is Air Watts a Better Stat?
Certain vacuum manufacturers show the power of their products in air watts instead of pascals. A watt indicates the amount of power used by the vacuum’s engine, so an air watt relates that power to its capacity to generate airflow. Since airflow takes into account the actual movement of air through the device, it comes closer to approximating real-world cleaning power than pascals. Even air watts aren’t standardized across robot vacuum manufacturers, however, and don’t have any kind of direct correlation to pascals.
Dyson’s most recent robot vacuum, the Dyson 360 Vis Nav, promises to deliver 65 air watts of suction. Dyson claims the machine is twice as powerful as any competitor, but that's hard to verify since pascals and air watts have no direct statistical correlation. That said, the Vis Nav picked up 53.6% of the sand from carpeting on my stress test. While that number isn’t twice the value of its closest competitors, it is the highest mark I’ve seen on the test to date.
While offering class-leading stubborn debris pickup in the real world, the Vis Nav has short battery life, sometimes gets lost, and lacks a competitive feature set for its high price, so it only earned average marks in my review.
Even air watts wouldn’t tell the whole story if all robot vacuums switched to it as the main suction power stat. Design and smarts would still affect cleaning performance in a way that the stat can't quantify, highlighting the importance of independent third-party reviews based on real-world testing.
Even so, because air watts combine power and airflow, the unit accounts for factors that the pure power-related figure of pascals doesn't, such as brush roll design. No stat is perfect, but I’d prefer it if robot vacuum manufacturers displayed the power of their machines in air watts instead of pascals.
Pascals Are Still Important, But Look at the Bigger Picture
I’m not saying that you should ignore pascals when shopping for a robot vacuum. Having a relatively uniform figure for raw vacuum power is better for a quick comparison than nothing, but you shouldn't view pascals as the be-all-end-all. In general, look for the features you want and prioritize those over pascals, as you can rest assured that a slightly higher pascal count from one unit to the next isn't an indication that it will actually clean your floors better.
For more buying advice, check out our list of the best robot vacuums we've tested—no matter the pascals, you can't go wrong with any of these top picks. And once you've found the right model, read up on our 10 simple tips for getting the most out of your robot vacuum.