You don’t have to buy two, but a lot of people end up wanting to. Most current robots store several floor maps, so you can carry it upstairs and it’ll recognize where it is. The catch is the dock — it stays put.

How multi-floor mapping actually works

Any robot worth buying today will store two or more maps and identify which floor it’s on when you set it down. You carry it up, hit start, and it recognizes the layout and cleans the saved zones. That part works well and has for a few years now.

What doesn’t move is the dock. So the robot upstairs has no place to empty its bin, no place to recharge mid-run, and no way to wash a mop pad. On a big upstairs it may run out of battery before it finishes, and with no dock to return to it just stops where it stands.

When the second robot pays for itself

If upstairs is a spare room and a bathroom you clean once a week, carrying the robot up is fine. If upstairs is where all the bedrooms are — which is where the hair, the dust and the dander actually live — you’ll get tired of hauling it within a month, and a second robot buys back real aggravation. A simpler, less expensive model upstairs paired with your main robot downstairs is a common and sensible setup.

One thing worth saying plainly: no robot vacuum climbs stairs. Not one, at any price. If somebody tells you otherwise they’re describing a concept video.

Dad’s Take

The robot handles two floors fine. It’s the dock that doesn’t. Decide based on how often you want to carry it.