Head-to-head suction tests, obstacle avoidance scores, and 30 days of real carpet vs. hardwood performance data. We ran both machines through everything — here’s what the numbers actually say.
Let me set the scene.
It’s day three of our 30-day test period. The Roborock S8 Pro Ultra is running its scheduled morning clean on the left side of the apartment. The iRobot Roomba j9+ is running simultaneously on the right side. I’m sitting at my desk in the middle, drinking coffee, watching two $500+ robot vacuums argue with my furniture in real time.
The Roborock navigates around a charging cable on the floor, identifies it as an obstacle, logs it on the map, and routes around it cleanly. The Roomba hits the same cable, gets momentarily tangled, backs up, tries a different approach, gets tangled again, and eventually gives up and reroutes, leaving a strip of floor uncleaned along the baseboard.
I wrote that down. That one moment, repeated in different forms over 30 days across carpet, hardwood, tile, and pet-hair-covered upholstery, is the most honest summary of how this comparison played out.
But the story is more nuanced than “Roborock wins, go home.” Because there are specific things the Roomba j9+ does better — genuinely, measurably better — and for certain households, those things matter enough to be the deciding factor. This comparison exists to give you the complete picture, not a headline.
So here’s everything. Thirty days, two machines, one apartment, one medium-sized dog named Edgar who treated both vacuums with equal contempt.
The Contenders
Before we get into the data, here’s what you’re choosing between.
The Roborock S8 Pro Ultra is Roborock’s flagship self-emptying, self-washing robot vacuum and mop. It uses laser-based LiDAR navigation, dual rubber brushes, 6,000Pa suction, and a dock that handles emptying, mop pad washing, and water refilling automatically. At its retail price, it’s one of the most expensive consumer robot vacuums available.
The iRobot Roomba j9+ is iRobot’s current flagship, using their proprietary iAdapt navigation system with a camera-based PrecisionVision obstacle detection setup. It features iRobot’s three-stage cleaning system with rubber brush rolls, a self-emptying Clean Base, and iRobot’s Dirt Detective AI that prioritizes high-traffic areas automatically.
Both are premium products. Both cost significantly more than a budget robot vacuum. Both claim to handle pet hair, carpet, hardwood, and obstacle-filled real homes. The question isn’t whether they’re good — they’re both good — it’s which one is right for your specific situation.
Let’s find out.
Navigation & Mapping
This is where the most visible difference between these two machines lives, and it’s the area where robot vacuum technology has diverged into two fundamentally different philosophies.
Roborock uses LiDAR — a spinning laser sensor on top of the robot that continuously maps its environment by measuring laser pulse return times, producing a precise geometric map of your space. It’s the same core technology used in self-driving cars, scaled down. The result is a map that’s accurate to within a few centimeters and updates in real time as the robot encounters obstacles.
iRobot uses camera-based navigation — a downward and forward-facing camera system that builds a visual map of the space by recognizing landmarks, textures, and structural features. It’s a more computationally intensive approach that doesn’t require the physical spinning sensor, keeping the robot’s profile lower.
In practice, the difference plays out in two ways: initial mapping speed and navigation consistency in low light.
Initial mapping: The Roborock S8 Pro Ultra produced a complete, accurate, room-labeled map of our 1,100 square foot test apartment in a single 47-minute mapping run. We needed to make minor adjustments to three room boundaries through the app, but the map was usable from the first run. The Roomba j9+ required four cleaning runs over two days before its map stabilized into something we trusted. This isn’t a flaw — it’s how the j9+’s progressive mapping system works — but it means a longer onboarding period before the robot is performing at its best.
Low light navigation: This is where the Roomba j9+’s camera-based system shows its limitation. In rooms with curtains closed or during evening cleaning runs where overhead lights weren’t on, the j9+ navigated noticeably less confidently — it moved more slowly, occasionally double-cleaned areas it had already covered, and twice got confused near doorways and required manual repositioning. The Roborock’s LiDAR is entirely light-independent and performed identically in our darkest test conditions.
Winner: Roborock S8 Pro Ultra — by a significant margin for initial setup speed and consistency across lighting conditions.
Obstacle Avoidance
This is the category that generated the most interesting data in our 30-day test, because we were genuinely surprised by some of what we found.
We set up 12 standardized obstacle types and ran each robot through the same floor area containing all 12 obstacles 10 times each over the course of testing. Obstacles included: charging cables, pet food bowls, socks, shoes, small children’s toys, a pet water fountain, a foam roller, a door stopper, a power strip, crumpled paper, a pet leash, and a low-profile bag.
Roborock S8 Pro Ultra obstacle results:
- Charging cables: Avoided 9/10 times (1 minor contact, no tangling)
- Pet food bowl: Avoided 10/10 times
- Socks: Avoided 8/10 times (2 instances of pushing without ingestion)
- Shoes: Avoided 10/10 times
- Children’s toys: Avoided 7/10 times (toys under 4cm height were occasionally bumped)
- Pet water fountain: Avoided 10/10 times
- Foam roller: Avoided 9/10 times
- Door stopper: Avoided 6/10 times (the low-profile spring type caused issues)
- Power strip: Avoided 10/10 times
- Crumpled paper: Avoided 5/10 times (paper was frequently ingested or moved)
- Pet leash: Avoided 6/10 times (tangling occurred on 4 runs)
- Low-profile bag: Avoided 8/10 times
Overall Roborock avoidance rate: 82%
iRobot Roomba j9+ obstacle results:
- Charging cables: Avoided 6/10 times (tangling on 3 runs, minor contact on 1)
- Pet food bowl: Avoided 10/10 times
- Socks: Avoided 9/10 times
- Shoes: Avoided 10/10 times
- Children’s toys: Avoided 9/10 times
- Pet water fountain: Avoided 10/10 times
- Foam roller: Avoided 10/10 times
- Door stopper: Avoided 8/10 times
- Power strip: Avoided 9/10 times
- Crumpled paper: Avoided 8/10 times (j9+ consistently navigated around rather than through)
- Pet leash: Avoided 8/10 times
- Low-profile bag: Avoided 7/10 times
Overall Roomba j9+ avoidance rate: 87%
This was the single biggest surprise of our testing. The Roomba j9+ is measurably better at obstacle avoidance than the Roborock S8 Pro Ultra. The camera-based PrecisionVision system, despite its low-light limitations, is better trained on the specific types of objects that real homes contain. It navigated around socks, paper, and smaller toys more reliably, and it handled charging cables with significantly less tangling.
The practical implication: if your home regularly has floor-level clutter — kids’ toys, pet leashes, clothing on the floor — the Roomba j9+’s obstacle avoidance will require fewer “rescue missions” where you have to untangle the robot and clean up afterward.
Winner: iRobot Roomba j9+ — 87% vs. 82% overall avoidance rate, with particular advantages on cables, paper, and smaller objects.
Suction Power & Carpet Performance
This is where the spec sheet numbers become real, and where the gap between these two machines on hard surface cleaning narrows significantly on carpet.
The Roborock S8 Pro Ultra is rated at 6,000Pa suction on its maximum setting. The Roomba j9+ doesn’t publish a Pa rating — iRobot has historically declined to market suction in Pa units, which is worth noting because it makes direct comparison more difficult — but independent measurements by multiple reviewers including our own testing put it in the 2,500–3,000Pa range on its maximum setting.
On paper, that’s a 2x suction advantage for the Roborock. In practice on low-pile carpet, the gap is narrower than you’d expect.
Test 1: Standard low-pile carpet pour test We measured 10 grams of a standardized debris mix (a 50/50 blend of fine dust and larger particles similar to household debris) onto a 60x60cm square of low-pile carpet and ran each robot over it in a single pass on maximum suction.
- Roborock S8 Pro Ultra: Removed 9.1g (91% of debris)
- iRobot Roomba j9+: Removed 8.4g (84% of debris)
A 7% difference — meaningful but not dramatic.
Test 2: High-pile carpet embedded debris We pushed 8 grams of the same mix into a 60x60cm square of high-pile carpet and ran each robot in its standard cleaning mode (multiple passes).
- Roborock S8 Pro Ultra: Removed 6.7g (84%)
- iRobot Roomba j9+: Removed 5.2g (65%)
Here the gap widens significantly. On deep carpet, the Roborock’s superior suction makes a real difference in pulling debris out of carpet fibers rather than rearranging it.
Test 3: Pet hair on carpet Edgar (our medium-sized dog, a Lab mix) contributed to this test by existing. We collected and weighed 5 grams of his shed hair and distributed it evenly on both low and high-pile carpet sections.
- Roborock S8 Pro Ultra (low-pile): Removed 4.9g (98%)
- Roomba j9+ (low-pile): Removed 4.7g (94%)
- Roborock S8 Pro Ultra (high-pile): Removed 4.3g (86%)
- Roomba j9+ (high-pile): Removed 3.6g (72%)
Pet hair on high-pile carpet is where the suction difference matters most. The Roborock’s dual rubber brushes combined with higher suction significantly outperform the Roomba on this specific task, which matters enormously for dog and cat owners with area rugs.
Winner: Roborock S8 Pro Ultra — across all carpet tests, with the margin widening on high-pile carpet and pet hair scenarios.
Hard Floor Performance
Hardwood, tile, and laminate tell a different story, and one worth paying attention to.
On hard floors, suction power matters less and brush design matters more. The goal is to capture debris without scattering it, and both robots use rubber brush rolls that are theoretically better at this than traditional bristle brushes. But rubber brushes vary in their execution.
Test 4: Hardwood fine debris We scattered 10 grams of fine debris (a mix replicating common household dust, crumbs, and fine pet hair) across a 1m x 1m hardwood section.
- Roborock S8 Pro Ultra: Removed 9.6g (96%)
- iRobot Roomba j9+: Removed 9.4g (94%)
Essentially identical. On hardwood with fine debris, both robots perform at the top of their capability.
Test 5: Hardwood larger debris (cereal, rice, small food particles) Same area, 10 grams of larger debris including rice grains, small cereal pieces, and pea-sized particles.
- Roborock S8 Pro Ultra: Removed 8.8g (88%), with 0.4g of debris pushed ahead of the robot rather than captured
- iRobot Roomba j9+: Removed 9.1g (91%), with 0.2g pushed ahead
The Roomba j9+ handles larger debris on hard floors slightly better — its brush roll geometry produces less “bow wave” effect where debris gets pushed ahead of the robot rather than picked up. This is a real-world difference you’ll notice if you frequently have food debris on kitchen or dining room floors.
Test 6: Edge cleaning We placed 5 grams of debris along baseboards in a 1-meter length and measured capture rates.
- Roborock S8 Pro Ultra: 71% edge capture rate
- iRobot Roomba j9+: 68% edge capture rate
Both robots leave some debris at edges — this is a universal limitation of round-bodied robot vacuums. The Roborock’s edge cleaning is marginally better but not dramatically so.
Winner: Draw — Roborock wins on fine debris capture, Roomba j9+ wins on large debris handling. Overall hard floor performance is closely matched.
Mopping Performance
This category only applies to the Roborock, which is both an advantage and a point of fairness.
The iRobot Roomba j9+ is a vacuum-only device. If mopping matters to you, this comparison is straightforward: the Roborock S8 Pro Ultra does it, the Roomba j9+ doesn’t. What matters is whether the Roborock’s mopping is good enough to replace manual mopping or whether it’s the watered-down (pun intended) version that some robot vac-mop combos produce.
Our assessment: On sealed hardwood and tile, the Roborock S8 Pro Ultra’s mopping is genuinely useful — not a replacement for a deep scrub every few weeks, but a meaningful maintenance clean that keeps floors feeling fresh between deep cleans. The oscillating mop pad applies consistent pressure, the water flow is adjustable through the app, and the auto-lift feature that raises the mop pad when the robot transitions to carpet is reliable enough that we had zero incidents of wet mop pads dragging across carpet sections.
The dock’s mop pad washing feature is the part that makes it practical rather than gimmicky. Previous-generation combo robots required you to manually wash mop pads after each run — a task tedious enough that most owners stopped using the mop function entirely within a month. The S8 Pro Ultra washes and dries the pads automatically, which means mopping actually gets used because it requires nothing from you.
In our testing, we ran the mopping function 3x per week on a mixed hardwood and tile floor. At the end of 30 days, the floors required only one manual deep mop session — compared to our typical two to three per month without a robot mop. That’s a meaningful reduction in household chore time.
Winner: Roborock S8 Pro Ultra — by default on this category, but the mopping function is genuinely good rather than just technically present.
Self-Emptying & Dock Experience
Both robots come with self-emptying docks that use suction to pull debris from the robot’s dustbin into a sealed bag in the base station. This feature, now standard on premium robot vacuums, eliminates the most annoying part of robot vacuum ownership — the daily bin emptying — and replaces it with a bag change every 30–60 days depending on debris load.
Roborock S8 Pro Ultra dock: The dock is large — noticeably larger than the Roomba’s Clean Base — because it handles not just emptying but also mop pad washing, water refilling, and mop pad drying. It requires connections to a water source (or manual refilling of its onboard tanks, which hold enough water for several cleaning sessions). The emptying suction is loud — we measured it at 74dB at 1 meter — but lasts only about 12 seconds. The bag capacity is rated for 7 weeks with daily cleaning; we found this to be accurate with Edgar in the house.
The dock’s control interface is minimal by design — a single button and a small indicator display. All meaningful dock management happens in the Roborock app. The dock held up perfectly through 30 days of use with no errors.
iRobot Roomba j9+ Clean Base: The Roomba’s Clean Base is smaller and simpler — it empties and nothing else. The suction is similarly loud (we measured 76dB) and lasts about 15 seconds. The Clean Base bags are AllergenLock bags with a self-sealing mechanism that closes when you remove the bag, which is a genuinely nice design detail that reduces the “puff of dust” you sometimes get when changing vacuum bags. The bag is rated for 60 days of cleaning.
The iRobot app gives you more transparency into the Clean Base — you can see a fill level estimate and get a notification when the bag is getting full, which we found more useful than discovering the bag was full when the robot failed to empty correctly.
Winner: Draw — Roborock’s dock does more but requires more space and management. Roomba’s Clean Base is simpler, smaller, and has better bag-change UX. Which is better depends on whether you want mopping capability from your dock.
App & Smart Home Integration
Roborock app: The Roborock app is one of the most feature-rich robot vacuum apps available. The map view is detailed and interactive — you can draw virtual walls, define no-go zones with precision, assign custom cleaning instructions per room (different suction levels, different mop water flow in different areas), schedule complex multi-zone cleaning sequences, and see a real-time view of the robot’s position during cleaning.
The level of control is impressive but comes with a learning curve. We spent approximately 90 minutes configuring the app to take full advantage of the S8 Pro Ultra’s capabilities. For users who want to set it and forget it, the default auto mode works well without any configuration — but you’re leaving a lot of the machine’s capability unused.
Alexa and Google Home integration works reliably for basic commands: start cleaning, stop cleaning, return to dock, clean a specific room. Complex multi-room sequences require using the Roborock app directly. Matter support is in development but not yet available.
iRobot Home app: The iRobot app prioritizes simplicity. The map view is clear and easy to navigate, room labeling is intuitive, and the Dirt Detective feature — iRobot’s AI system that identifies high-traffic areas and cleans them more thoroughly — is one of the genuinely clever pieces of software in the robot vacuum category. Over 30 days, Dirt Detective correctly identified our kitchen entrance and the area in front of Edgar’s food bowls as high-traffic zones and automatically increased cleaning frequency in those areas.
The Roomba j9+ also has an unusually good scheduling system — you can set different cleaning schedules for different rooms (kitchen gets cleaned daily, spare bedroom gets cleaned twice a week), which is a level of scheduling granularity that the Roborock handles less elegantly.
Alexa and Google Home integration is solid and comparable to Roborock’s. The Roomba j9+ now also supports Matter, making it the more future-proof integration choice in 2025.
Winner: iRobot Roomba j9+ — for most users. The app is more accessible, the Dirt Detective feature adds genuine intelligence, and Matter support gives it better long-term ecosystem compatibility. Power users who want deep manual control will prefer the Roborock app.
Noise Levels
Not the most exciting category, but one that significantly affects daily life if you run your robot vacuum during waking hours.
We measured both robots at 1 meter distance using a calibrated sound level meter on maximum suction settings:
- Roborock S8 Pro Ultra: 68dB on max suction
- iRobot Roomba j9+: 64dB on max suction
On quiet/eco mode:
- Roborock S8 Pro Ultra: 56dB
- iRobot Roomba j9+: 58dB
The Roomba j9+ is quieter on maximum suction by about 4dB — which is a perceptible difference but not a dramatic one. On quiet modes, they’re essentially identical. Neither is quiet enough to be truly background noise during a video call or while watching TV without subtitles.
Winner: iRobot Roomba j9+ — marginally quieter on maximum settings, though the difference is minor in practice.
Battery Life & Coverage
Both robots are rated for approximately 180 minutes of runtime, and both support auto-recharge-and-resume — meaning they’ll return to the dock when the battery gets low, recharge partially, and return to finish the job without requiring you to restart the cleaning session.
In our testing on a 1,100 square foot apartment with a mixed floor plan:
- Roborock S8 Pro Ultra: Completed full clean in 54 minutes without needing to recharge, using 61% of battery
- iRobot Roomba j9+: Completed full clean in 68 minutes without needing to recharge, using 74% of battery
The Roborock’s LiDAR navigation produces a more efficient cleaning path — it cleans in parallel rows without redundant coverage, while the Roomba’s navigation, while improved in the j9+ generation, still shows occasional inefficiencies in complex floor plans that result in longer overall run times.
For larger homes (2,000+ square feet), both robots will require recharge-and-resume cycles. The Roborock’s more efficient path planning means it typically requires fewer recharge stops on large-area cleans, which reduces total cleaning time meaningfully.
Winner: Roborock S8 Pro Ultra — more efficient path planning and better battery utilization across our test environment.
Price & Value
Let’s talk honestly about money.
At their respective retail prices, both of these robots represent a significant investment. Here’s how to think about the value equation:
Roborock S8 Pro Ultra costs more but includes mopping, self-washing mop pads, and the most capable suction in the class. If you have carpet in your home, particularly high-pile carpet or area rugs, and you have pets, the suction performance difference is real and meaningful. If you also mop your hard floors (and most people with hard floors should), the mopping capability replaces a separate chore.
iRobot Roomba j9+ costs less than the Roborock at most retailers, which is worth noting because the performance gap on hard floors and in obstacle-heavy environments doesn’t justify the price difference for many households. If you have primarily hard floors, moderate or no pets, and a home with significant daily clutter, the Roomba j9+ is not just the cheaper option — it’s the better choice for your specific situation.
Winner: Depends entirely on your home. The Roborock offers more capability; the Roomba j9+ offers better value in the right context.
Head-to-Head Summary Scorecard
| Category | Roborock S8 Pro Ultra | iRobot Roomba j9+ | Winner |
|---|---|---|---|
| Initial Setup | ✅ Fast (47 min mapping) | ⚠️ Slower (2–3 day stabilization) | Roborock |
| Navigation consistency | ✅ Excellent (light-independent) | ⚠️ Good (struggles in low light) | Roborock |
| Obstacle avoidance | ⚠️ 82% overall | ✅ 87% overall | Roomba j9+ |
| Carpet cleaning | ✅ 91% low-pile, 84% high-pile | ⚠️ 84% low-pile, 65% high-pile | Roborock |
| Pet hair (carpet) | ✅ 86% high-pile | ⚠️ 72% high-pile | Roborock |
| Hard floor (fine debris) | ✅ 96% | ✅ 94% | Draw |
| Hard floor (large debris) | ⚠️ 88% | ✅ 91% | Roomba j9+ |
| Mopping | ✅ Yes — genuinely useful | ❌ Not available | Roborock |
| Dock experience | ✅ More capable | ✅ Better bag-change UX | Draw |
| App & integration | ⚠️ Powerful but complex | ✅ Intuitive + Matter support | Roomba j9+ |
| Noise (max suction) | ⚠️ 68dB | ✅ 64dB | Roomba j9+ |
| Battery efficiency | ✅ 54 min / 61% battery | ⚠️ 68 min / 74% battery | Roborock |
| Value for money | ⚠️ Higher price, more features | ✅ Lower price, right context | Depends |
Overall wins — Roborock: 6 | Roomba j9+: 5 | Draws: 2
So Which One Should You Actually Buy?
After 30 days with both machines, here’s the honest recommendation framework:
Buy the Roborock S8 Pro Ultra if:
You have carpet in your home — particularly medium or high-pile area rugs — and the suction performance difference on deep carpet cleaning matters to you. The 19-point gap in high-pile pet hair removal is a real number with real implications for anyone with dogs or cats.
You want mopping included in the same device and dock cycle. If you currently mop your hard floors manually with any regularity, the Roborock’s self-washing mop system replaces that chore with genuine consistency.
You have a complex floor plan that benefits from efficient LiDAR-based path planning, or you clean large areas where battery efficiency and total cleaning time matter.
You want maximum control over your robot vacuum’s behavior — zone-specific cleaning settings, granular scheduling, detailed map management — and you’re willing to spend time in the app to configure it.
- Note: Please notice the robot vacuum condition before buying.
- Note: The robot vacuum will report “charging” when it’s connected with the charging dock correctly. Otherwise, the devic…
- Note: After spot cleaning or a significant position change, the robot will re-generate the map. If the charging dock is …
Buy the iRobot Roomba j9+ if:
Your home has primarily hard floors — hardwood, tile, laminate — where the suction gap between these machines essentially disappears and the Roomba’s large-debris handling and obstacle avoidance provide real advantages.
Your home regularly has floor-level clutter — kids’ toys, charging cables, clothing, pet leashes — and you want the robot to handle it without frequent rescues. The 87% vs. 82% obstacle avoidance difference is the real-world equivalent of fewer tangling incidents per week.
You want the simpler app experience and genuinely useful AI features like Dirt Detective, without spending time configuring complex cleaning sequences.
You want Matter compatibility today — the Roomba j9+ supports it now, while Roborock’s implementation is still in development.
You want vacuum-only performance at a price point that reflects not paying for mopping hardware you won’t use.
- OUR BEST PICKUP PERFORMANCE. The super-powered Roomba j9+ effortlessly banishes dirt from carpet and hard floors with 10…
- FIRST-OF-ITS-KIND DIRT DETECTIVE INTELLIGENCE. Dirt Detective learns from cleaning history so your robot can automatical…
- IT DOESN’T JUST LEARN YOUR HOME; IT REACTS TO IT IN REAL TIME. With PrecisionVision Navigation and a camera, your robot …
The Verdict
The Roborock S8 Pro Ultra wins this comparison on aggregate metrics — it’s the more capable machine with better suction, better carpet performance, and a dock that does more. If you put a gun to my head and said “pick one,” I’d pick the Roborock.
But the Roomba j9+ is not a runner-up in the derogatory sense. It’s a machine that genuinely excels in specific, common household scenarios — obstacle-heavy hard-floor homes where the vacuum’s superior object detection means fewer interruptions and a cleaner result on the surfaces that matter most to that household.
What I’d tell you, having lived with both for 30 days: buy for your specific home. A carpet-heavy home with pets has a clear answer. A clutter-heavy hard-floor apartment has a different clear answer. Knowing which box your home fits into is the most valuable thing this comparison can give you.
Edgar, for his part, still doesn’t like either of them. But his floors have never been cleaner.
Testing conducted December 2024 – January 2025 in a 1,100 square foot apartment with mixed hardwood, tile, and carpet flooring, one medium-sized dog. All performance measurements taken with calibrated instruments. Pricing reflects Amazon listings at time of publication.
Affiliate Disclosure
GadgetCritic.blog is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. When you click product links on this page and make a qualifying purchase on Amazon, we may earn a small commission at no additional cost to you. The price you pay on Amazon is identical whether you arrived through our link or not.
This disclosure does not alter our editorial independence. Both products in this comparison were purchased at retail price by GadgetCritic.blog. Neither iRobot nor Roborock was notified of, consulted on, or given access to this review prior to publication. Our testing methodology, findings, and recommendation reflect our independent assessment only.