Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Roborock - S8 Pro Ultra | Roborock - S9 MaxV Ultra |
|---|---|---|
| Suction | 6000 Pa | 22000 Pa |
| Water tank | 180 ml | 300 ml |
| Noise | 67 dB | 65 dB |
Between the S8 Pro Ultra and S9 MaxV Ultra, the S8 Pro Ultra comes out ahead in several specs, while the S9 MaxV Ultra wins on suction / water tank. Overall, the S8 Pro Ultra scores 79 and the S9 MaxV Ultra scores 88 on our Mars Score.
Which should you buy?
The S9 MaxV Ultra is the clear pick on raw spec strength, leading by 9.0 points on the Mars Score. The margin is wide enough that the underdog only makes sense if its individual strengths line up with what you specifically need.
The S8 Pro Ultra does not pull ahead on any single popular-comparison spec — its strengths sit in the spec-table groups rather than the headline advantages.
Pick the S9 MaxV Ultra if you care most about suction / water tank. Its strongest claims are suction, water tank, noise. The single most decisive one: Suction — 266.67% more. 22000 Pa vs 6000 Pa.
Both ship with comparable mopping, lidar, battery life, so those specs do not separate the two — focus on the differences below.
Bottom line: the S9 MaxV Ultra is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Which should you buy: Roborock - S8 Pro Ultra or Roborock - S9 MaxV Ultra?
Roborock - S9 MaxV Ultra leads the current Mars Score by 9.0 points.The more useful decision is the trade-off behind that result: compare suction against the way you will actually use the product.
Choose Roborock - S8 Pro Ultra if…
Roborock - S8 Pro Ultra does not lead a decisive measured field here, so choose it for price, ecosystem, design, or availability when those matter more to you.
Choose Roborock - S9 MaxV Ultra if…
Roborock - S9 MaxV Ultra has the measurable edge on suction pa, water tank capacity ml, noise db.
This is a structured comparison of the published catalog values. It is not a claim of identical real-world performance across every workload; use the linked spec drill-downs and methodology page to inspect the inputs.
Why Roborock - S8 Pro Ultra wins
- No decisive advantages.
Why Roborock - S9 MaxV Ultra wins
- ▲Suction — 266.67% more. 22000 Pa vs 6000 Pa.
- ▲Water tank — 66.67% more. 300 ml vs 180 ml.
- ▲Noise — 2.00 dB less. 65 vs 67.
Spec comparison
Cleaning
| Spec | Roborock - S8 Pro Ultra | Roborock - S9 MaxV Ultra |
|---|---|---|
| Suction | 6000 Pa | 22000 Palead |
| Mopping | true | true |
| Water tank | 180 ml | 300 mllead |
| Dustbin | 400 mllead | 350 ml |
| Carpet detection | true | true |
Navigation
| Spec | Roborock - S8 Pro Ultra | Roborock - S9 MaxV Ultra |
|---|---|---|
| Lidar | true | true |
| Camera navigation | true | true |
| AI obstacle avoidance | true | true |
| Max climb | 20 mm | 40 mmlead |
Autonomy
| Spec | Roborock - S8 Pro Ultra | Roborock - S9 MaxV Ultra |
|---|---|---|
| Battery life | 180 min | 180 min |
| Self-empty base | true | true |
| Self-wash mop | true | true |
| Self-dry mop | true | true |
| Noise | 67 dB | 65 dBlead |
Frequently asked
Which has stronger suction, S8 Pro Ultra or S9 MaxV Ultra?+
S9 MaxV Ultra delivers 22000 Pa vs 6000 Pa.
Do S8 Pro Ultra or S9 MaxV Ultra mop?+
Both can mop.
Which has a self-emptying base, S8 Pro Ultra or S9 MaxV Ultra?+
Both ship with a self-emptying base.