iRobot Roomba s9 Review
Our Analysis and Test Results
While the s9 is arguably one of — if not the — best robot vacuum that we have tested, we think the vast majority of people will be better suited by one of the slightly lower-cost models that scored almost as well — especially if they don't have a ton of pet hair to pick up. We tend to think of robot vacuums as maintenance cleaners for your home — something that can prolong the time between cleanings, but not supplant them entirely. This makes it hard for many people to front the premium price of the s9, especially when they will most likely still need to purchase a more traditional vacuum cleaner. You also have the option of purchasing the self-emptying docking station for this robot, allowing you to go even longer without emptying the collection bin but this does increase the total cost quite a bit.
We have spent close to four years testing all the most promising robot vacuums on the market to help you find the very best, buying all the most promising models as they have been released and testing side-by-side, updating this review whenever a particularly noteworthy model has hit the market. We graded and scored the performance of each robot vacuum in six weighted rating metrics, with the Roomba s9's results in each outlined in the following sections.
Responsible for 30% of the s9's final score, the Navigation metric is the most important out of all of our rating metrics. For this metric, we assessed how easy each robot can navigate around various pieces of furniture, how well it did at finding its docking station, and if it can handle high-contrast flooring and clean under low pieces without its navigation sensors triggering a ton of false-positives that cause it to avoid the entire area. The Roomba s9 did very well, earning one of the higher scores of the group.
The s9 had no issues at all at finding its docking station in our tests, regardless if it was in the same room or a different room as its charging base when it was sent home.
The s9's navigation sensors didn't trigger any false-positives for obstacles or drops when it transitioned from dark to light flooring or vice-versa. This robot also had no issue cleaning under low pieces of furniture and would clean wherever the robot could physically fit.
In terms of navigating around a set of furniture in a single room, the Roomba s9 did well but we weren't exactly blown away by its performance. In the first trial, the s9 seemed quite clumsy, crashing into a decent amount of our test furniture. It doesn't seem to have any physical bumpers, as it would repeatedly ram the same piece of furniture. This seemed to be a bit suspicious for a top-tier robot so we ran a training run and tried it again. It did significantly better in the second trial, making it through the tight spaces under and around a table and chairs without issues but still did have the occasional collision.
The s9's navigation is supposed to improve each time it cleans the same area but we felt that some of its predecessors handled our test room a little more delicately right from the start. However, the s9 still did far better than the lower tier of robots.
Our second metric also focused on the navigation abilities of each robot but this time we were more concerned with how much of your home each 'bot effectively cleans, compared to if it can avoid getting stuck in difficult areas. In this metric, we compared the ability of each robot at cleaning multiple rooms, how much coverage their spot clean functions have, if they can automatically recharge and resume cleaning if the battery level drops too low, how effectively you can implement barriers for do not clean zones, and how much of a furnished room it actually cleans. The s9 again did very well, earning one of the top scores of the entire group.
The s9 has an impressive set of spot cleaning abilities, covering an area just over 12 sq. ft. The s9 follows the same cleaning pattern as the other Roomba vacuums, spiraling out and then back into the point where you it started from. Additionally, you can send the s9 to clean a specific room once it has made a map of your house.
This robot easily cleans multiple rooms and does have the capability to find its charging base and resume cleaning if the battery dies while cleaning. The s9 is compatible with iRobot's virtual barrier system but none are included with the robot and must be purchased separately. You can set the virtual barrier to project a wall that measures 10' in length or a circle that has a 4' diameter. You can also create virtual no-go zones in the companion app without using a base station.
The s9 is relatively fearless while cleaning and will enter cramped and confined areas without hesitation to clean. It usually gets the vast majority of the areas in our test room but does habitually miss areas around its charger, leaving some of the rice we scattered around it untouched even after three passes. The s9 can also get slightly off while doing rows in its lawnmower pattern and fail to overlap, leaving a small amount of mess between rows.
Our third set of tests dealt with how proficient the Roomba s9 is at cleaning soft floors. We graded its performance at picking up flour, rice, oats, and Mini-Wheats from various types of carpet, as well as how closely the s9 can clean along the edges of a carpeted room to determine scores. It continued its excellent showing, tying for one of the top scores of the whole group in this metric, which constitutes 15% of each robot's final score.
The Roomba s9 did well in our edge cleaning test, getting within a half-inch of the walls and the corners in our robot test pen. It by far delivered the best performance of all the Roomba models we have previously tested.
This robot vacuum also completely floored us in our flour test, which is one of the most difficult cleaning challenges we put these products through. There was only a tiny bit of flour left after the s9 did its cleaning passes on the top of the carpet that wasn't noticeable unless you had your face right at the carpet.
The s9 continued its cleaning dominance into our rice test on the flatter carpet, only leaving 1-2 grains behind after the test. We also noticed that it seems the s9 has some sort sensor inside that alerts it if it misses some of the mess on the carpet. It didn't collect a ton of rice on the first pass but then backed up and went over it again until it collected most of it. Performance dropped a bit with the fluffy carpet but the s9 still only left about an eighth of a teaspoon of rice behind deep in the piles of the carpet. It did about the same with the oats but the performance was flipped, with the s9 doing better with the fluffier carpet than the low-pile carpet, as it missed a decent amount of crumbs on the flat carpet.
This Roomba finished out with a strong showing with the larger Mini-Wheats, sucking up all of them from the medium-pile carpet and only leaving half of one behind on the low-pile carpet.
Hard Surface Cleaning
We repeated our carpet cleaning tests on a section of laminate flooring for this testing metric, which also is responsible for 15% of the final score for each vacuum. The s9 again did very well but its relative performance dropped slightly, keeping it out of the top spot when it comes to cleaning hard floors.
The s9 did even better at cleaning in close to the edges of the test pen, as its rotating side brush is significantly more effective on the hard floor than on the carpet. It still left a border of flour around the edges that measured about ½" across but it cleaned much further into the corners this time around.
The s9 very much impressed us with its performance at cleaning up flour from the laminate floor. It left almost no residue at all and didn't fling any to the side. Its wheels did pick up some flour but it didn't track it around.
Regrettably, the Roomba s9 only did a so-so job when it came to collecting rice and oatmeal. It easily picked up the bulk of the mess in both of these tests but the rollers tend to fling some of the rice and oats to the side. This usually gets thrown in the path of the robot, so it gets cleaned up eventually but it does occasionally miss some of the debris.
It finished with an alright showing with the larger pieces of cereal, sucking up four of the six Mini-Wheats in our test. It does have the clearance to roll over them but they do periodically get bound up under the robot and miss the extractor head or get pushed around instead of getting picked up.
Our last cleaning metric assessed the ability of each robot vacuum to pick up after your furry friends, which accounts for 10% of its total score. To score the performance of each vacuum, we spread out a measured amount of pet hair on both flat and fluffy carpet, then tasked the Roomba s9 with cleaning it up. It did exceptionally well, earning one of the top scores out of the entirety of our testing process.
The Roomba s9 collected 53% of the hair we spread out from the fluffy carpet and 50% from the low-pile carpet. While this might not sound that impressive, the s9 collected 10-30% more pet hair than almost every other vacuum in the group.
Our final metric ranked and compared al of the different internet-connected features each of these products have, which constitutes the remaining 10% of the total score. We awarded points based on how reliable the WiFi connection was in our tests, if the robot can integrate with other smart home products, and the various features and functions that each robot has. The Roomba s9 finished with another excellent score, putting it right at the top of the group when it comes to smart connect abilities.
We never really had any issues with this robot staying connected to our WiFi throughout our testing and this model of robot vacuum is compatible with various smart home systems, such as Alexa, IFTTT, or the Google Home Assistant.
Through the mobile app, you can locate the robot, view a cleaning map of the house, adjust the suction power and other cleaning settings, and set maintenance reminders for things like the filters.
It is also exceptionally easy to set up a schedule with the s9's companion app, which offers you a ton of different options to customize its cleaning routine. You can even have it clean specific rooms once it has created a map of your house.
You can't adjust the schedule from the robot, you can only use the mobile app. However, you can start a spot clean, full cleaning cycle, or send the robot to its docking station using the three dedicated buttons on the robot.
This is a great robot vacuum but it is far more expensive than many other good vacuums out there, making it hard to recommend as a bargain buy.
Overall, it's hard to find many negative things to say about the Roomba s9. It thoroughly impressed us in all of our cleaning tests. The s9 has solid navigation abilities and a decent suite of smart functions but it is a bit pricey for most people's budgets. It's a fantastic vacuum that we highly recommend if you want a top-tier robot that picks up pet hair like a champ, otherwise, you might be better served by one of the less expensive models.