Robot vacuum: what actually matters
Every robot vacuum cleans. The ones people stop using after three months fail on navigation, dock maintenance or fit — never on suction. This guide orders the criteria by how much they change your week.
The criteria, in the right order
| Rank | Criterion | Why it dominates |
|---|---|---|
| 1 | Dock footprint & clearance | If it doesn't fit, nothing else matters. The top cause of returns. |
| 2 | Navigation type | Determines whether it finishes a run or gets stuck twice a week. |
| 3 | Dock maintenance | Wash tray access decides whether you keep using the mop. |
| 4 | Edge reach | Visible on hard floors; a 4–6 cm ring you'll wipe by hand. |
| 5 | Consumable cost | $75–120/year is normal; proprietary parts can double it. |
| 6 | Suction (Pa) | Above ~4,000 Pa, differences are mostly marketing. |
Navigation: LiDAR vs camera
LiDAR builds an accurate map in the dark and handles long hallways predictably. Its weakness is small objects — it sees geometry, not meaning, so a black cable can be invisible. Camera + AI recognises objects and avoids them better, but needs light and can be fooled by mirrors and glass.
Both are fine. What you should avoid is a robot with neither — the random-navigation units sold under $300 that bounce around and miss rooms entirely.
The dock questions nobody asks
- Can you remove the wash tray without tools? If not, you'll stop washing the mop within a month.
- How often does the dust bag need changing? Four to six weeks with pet hair is realistic; "seven weeks" is best-case.
- Does it need plumbing? Auto-refill docks require a water line. Without one, you'll still fill a tank — just less often.
- Does a clog mean disassembly? Search owner reports for "clog" before buying. This is where cheap docks fail.
Dock depth is typically 45–50 cm plus clearance, and height matters if it sits under a cabinet. Measure the gap, then check the spec sheet — not the other way round.
Do you need a mop?
If more than half your floor is carpet, no. Mop modules add weight, dock complexity and maintenance for a function that lifts for most of the run. Spend the difference on navigation instead.
If your floors are mostly hard, a self-washing mop is the single feature that changes your routine — it removes the hand-washing chore that makes people abandon mopping robots. That is the argument for the Qrevo S over a cheaper vacuum-only unit.
Two-year cost worksheet
| Line item | Typical | Watch for |
|---|---|---|
| Purchase | $300–$1,200 | Sale cycles move 20–30% |
| Dust bags | $25–45/yr | Proprietary shapes cost more |
| Mop pads / brushes | $30–55/yr | Third-party options exist for popular models |
| Filters | $15–25/yr | Washable filters are rarer than claimed |
| Repairs | $0–150 | Out-of-warranty wheel modules are the usual failure |
When to stop shopping
Stop at $500–700 if you have hard floors and an open plan. The Qrevo S is the current value reference: self-wash, auto-empty, adequate avoidance.
Pay more only if cables and pet toys are regularly on your floor, or if you genuinely need corner reach. Above $1,000 you're buying obstacle avoidance and edge mechanics, not cleaning power.
Don't buy at all if you can't tidy before a run, or if your home is mostly carpet with tight furniture gaps. A $150 cordless stick will serve you better.
FAQ
Are self-emptying docks worth it?
Yes if you have pets or allergies — the point is not convenience but that you stop touching dust. If neither applies, a manual bin every two days is tolerable.
Do robot vacuums work on thick carpet?
They maintain, they don't deep clean. High-pile rugs need a plug-in vacuum; a robot will mostly fluff the surface.
How long do they last?
Three to five years for the robot, with wheel modules and batteries the usual early failures. Consumables are annual.
Related: Roborock Qrevo S review · All robot vacuum coverage