The sofa problem
The most common regret has nothing to do with cleaning power.
Ask owners what they wish they had checked, and the answer is rarely suction. It is that the machine does not fit under the sofa, the bed, or the kitchen units — which are precisely the places that accumulate dust and that you cannot easily reach yourself.
Where the height comes from
A LiDAR turret adds two to three centimetres to overall height, and that is frequently the exact amount that decides the outcome. This is why models are split into two design philosophies:
| Design | Typical height | Trade-off |
|---|---|---|
| Fixed LiDAR turret | ~9.5–11cm | Excellent mapping, cannot get under low furniture |
| Retractable LiDAR | ~8–9cm | Raises to scan, lowers to clean. Best of both, costs more |
| Camera / vision only | ~8–9.5cm | Slimmer, needs some light, privacy consideration |
The measurements to take
- Lowest clearance in the house. Measure floor to underside at the lowest point of every piece of furniture you want cleaned under. The lowest one sets your limit
- Subtract 1cm. A machine that exactly matches your clearance will scrape, wedge or get stuck. Leave margin
- Check for cross-braces. Many sofas have a support bar set back from the front edge. The machine fits going in and catches on the brace
- Measure the tallest threshold you need it to cross
- Measure the dock space, including height if it goes under a shelf
The cross-brace trap
This one catches people who measured correctly. The front edge of a sofa may have 11cm of clearance while a support rail 20cm back has 8cm. The machine drives in confidently and grounds out where you cannot see it.
Check by sliding a book of known thickness underneath as far as it will go, rather than measuring only at the visible edge.
If your furniture is too low
Three options, in order of cost:
- Furniture risers. A few centimetres of lift on sofa and bed legs, cheap, and often solves the problem entirely
- A no-go zone plus occasional manual cleaning under there
- A slimmer machine — retractable LiDAR or camera-based
Risers are worth trying first. They cost a fraction of upgrading the vacuum and frequently convert an impossible clearance into a comfortable one.
Height is a hard constraint. Check the stated unit height against your lowest clearance before ordering. Compare by height → Advertising — we may earn a commission.
Common questions
What height robot vacuum do I need?
Measure the lowest clearance under any furniture you want cleaned, then subtract about 1cm for margin. That figure is your maximum machine height. LiDAR turrets add two to three centimetres, which is often what decides whether it fits.
Why does my robot vacuum get stuck under the sofa?
Usually a cross-brace — a support rail set back from the front edge with less clearance than the visible opening. Check by sliding a book of known thickness underneath as far as it goes rather than measuring only at the edge.
What if my furniture is too low for any robot vacuum?
Furniture risers on sofa and bed legs are the cheapest fix and often solve it entirely. Otherwise use a no-go zone and clean under there occasionally by hand, or buy a slimmer retractable-LiDAR model.