Seven things to measure before you buy a robot mower

Robot mowers are the only machine in this whole category sold against hard published limits rather than soft claims. That is good news: instead of arguing about whether one is any good, you can measure your own garden and get a yes or a no in about ten minutes.

1. Lawn area, against 5,445 square feet

The Segway Navimow i105N publishes coverage of up to 1/8 acre, with Segway noting up to 0.15 acre depending on layout. An eighth of an acre is 5,445 square feet. That is the first and bluntest filter, and it disqualifies most of the lawns people imagine buying a robot for.

If you are over the limit, the honest alternatives are a walk-behind for a third of an acre — the Greenworks LM2054 is rated to exactly that — or, past an acre, an electric rider.

2. The steepest slope, against 16 degrees

Segway publishes a 16 degree maximum slope. This is the only published gradient limit we have found from any mower manufacturer of any type, and it is a hard limit rather than a suggestion: above it the machine loses traction on wet grass.

Do this at the steepest point, not the average one. A single bank across the middle of an otherwise flat lawn is enough to make the machine unable to reach half its territory.

3. The narrowest passage between sections

The i105N publishes a 7.1 inch cutting width. Segway does not publish an overall body width on the page we cite, so we cannot tell you the minimum gap it will drive through — and that gap is what decides whether a side passage between the front and back lawn is navigable.

4. Cut height, against 2 to 3.6 inches

Minnesota Extension guidance for a typical residential lawn is to maintain 3 inches or higher. The i105N publishes a 2 to 3.6 inch range, so it can hold 3 inches with 0.6 inches of headroom, and it cannot hold a 4-inch lawn at all.

The compensation is that a robot mower obeys the one-third rule better than any human: cutting a fraction of an inch daily is exactly the little-and-often pattern the research supports. We work through where the height guidance comes from on the mowing height guide.

5. Growth rate, against a 40% duty cycle

In peak spring growth on fertile soil, a robot on a restricted daytime schedule can fall behind. The usual answer is to extend the running window rather than to buy a bigger machine — which brings the 58 dB published noise figure into play, because a quiet machine can run at times a loud one cannot.

6. Where it will run, against 58 dB

58 dB(A) published is quieter than any blower we have specs for and close to normal conversation. It is one of very few machines in this entire category with a published decibel figure at all. That matters because the whole model depends on the machine running while you are living around it — on a terrace, near a bedroom window, during a barbecue.

7. Where it lives in winter

The i105N publishes a 24 lb weight, light enough for one person to carry to a shed or a garage shelf. That is a genuine advantage over any other mower here: at the end of the season it goes indoors rather than being winterised in place.

Storage guidance for the battery is model-specific and belongs in the operator's manual, not on a comparison site — we do not have a Segway statement to cite on charge level or storage temperature, so we will not invent one.

#ad Check the Segway Navimow i105N price on Amazon — how we're funded.

The checklist, in one place

What we cannot tell you

• Body width and minimum passage. Not published on the page we cite. Ask before buying if your lawn has a narrow link.
• Ground clearance or roughness tolerance. Segway publishes a slope limit but no roughness specification.
• Setup time. No published figure, and it will depend entirely on the shape of your boundary.
• How well it handles obstacles. That needs hands-on use, and we have not used it.