Aeno RC3S

Suction in pascal, as the maker measures it. More pascal helps on carpet, but it says little about how well the robot picks grit off a hard floor.

How the mop is built: flat pads, two spinning discs or a roller. Discs press harder on dried-on dirt, a roller rinses itself while it works.

How much clean water the robot carries. It sets how long it mops before a refill, which a dock does by itself.

How the robot maps your home and follows that map. Lidar measures with a laser and works in the dark, a camera looks along and recognises more.

The highest threshold the robot takes, as the maker states it. Measure your own: the step into a bathroom or onto a balcony is often higher.

How tall the robot is. It decides whether it fits under your sofa, bed or cabinet.

How wide the robot is. Narrower gets between chair legs more easily, wider usually means a bigger dust bin.

What the robot weighs. It counts most if you carry it up a staircase every day.

How much dust the robot holds before you empty it. It matters less with an auto-empty dock, which empties the bin after every run.

The noise in decibels, in the setting its source names: makers mostly give the standard setting, shops often the highest. 65 dB is like a vacuum at half power, 55 dB like a conversation.

The capacity of the battery. It hints at the runtime, but how much the robot draws counts just as much.

How long the robot cleans on one charge, at its quietest setting. After that it recharges and carries on where it stopped.

Which voice assistants the robot works with, such as Google Assistant or Alexa.

The warranty the maker gives in the Netherlands. Consumer law here stands apart from it and can last longer.