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Robot mower sizer

Enter your lawn area and the steepest slope. The sizer adds a margin for the shape of your lawn and compares it with the area and slope each maker publishes.

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Your lawn

Grass only, without the house, the drive and the beds. The lawn area calculator adds up shapes for you.

Steepest part of the lawn

That is 8.5°. The slope calculator turns rise and run into percent.

Lawn shape

Some beds, trees and corners. The rating it needs is your area × 1.35.

How it should run

When it may mow

Mowing any time, day or night. No extra margin.

Boundary wire

Models with and without a boundary wire both count.

Sky over the lawn

Trees or buildings over the lawn matter for models that steer by satellite alone. They get a warning, not a failure.

More checks: passage, separate areas, budget
inches

The narrowest gate or path between lawn areas. Few makers publish the width a mower needs, so this adds a note and never rules a model out.

Front and back lawns with no grass between them count as two.

USD

The most you would pay, in USD. A model without a published price for the US stays in the list with a note.

See the results

Results

Enter your lawn area to check the 33 mowers sold in the US.

The sizer checks 33 robot mowers sold in the US against your lawn and shows the working for each verdict. Start with the area of grass, or try an example size:

What the sizer checks

A rating does not say how much beds, corners and short mowing hours cost, so the sizer adds a margin, a rule of thumb. Beds, trees, corners and narrow strips make a robot drive further for each square meter of grass, so the sizer multiplies your lawn by a factor for its shape, and again when the mower may only run in daytime.

Margin added to your lawn area
Your lawnFactor
Open: one simple shape1.2
Typical: some beds, trees and corners1.35
Complex: many obstacles and tight spots1.5
Mowing in daytime onlya further 1.5

Rating needed = lawn area × shape factor × hours factor. An 800 m² (8,611 sq ft) lawn of typical shape, mowed at any time, needs 800 × 1.35 = 1,080 m² (11,625 sq ft).

Makers state area on different bases. Most give a maximum; some give the size they recommend and allow more. The sizer compares your lawn with the rating itself, or with 1.2 times a recommended figure, and each result card names the basis, such as "rated for lawns up to" or "recommended for lawns up to".

The four verdicts

  • Fits: the rating covers your lawn with the margin added, and the slope limit is at least 5 percentage points above your slope.
  • Tight: the rating covers the lawn but not the margin, or the slope limit is above your slope by less than 5 points.
  • Does not fit: the rating is below the lawn itself, the slope limit is below your slope, or a hard limit rules the model out: a boundary wire you do not want, separate lawns it cannot handle, or a price above your budget.
  • Needs a check: nothing rules the model out, but the maker does not publish its slope limit, or whether it handles separate lawns when you have more than one.

Sky cover, the narrowest passage, the number of zones a maker states, a missing price and a rating more than 6 times your lawn add notes to a card. They never rule a model out.

The order of the results

Inside each group the closest fit comes first: the smallest limit that still covers the rating needed, then the lower price in your region, then the larger slope margin. You can sort by price, by most headroom or by steepest slope instead. With Wire is fine chosen, boundary wire models come first in each group. Whether a link can earn a commission never changes the order.

The factors are rules of thumb. The methodology states each one with the slope, wire, satellite and passage rules.

Questions about the mower sizer

Why does the sizer ask for more than the lawn area?
A rating does not say what beds, corners and short mowing hours cost, so the sizer adds a margin of its own, a rule of thumb. The shape factor, 1.2 to 1.5, covers the extra driving around beds and corners, and daytime only mowing adds 1.5 because the mower has fewer hours. A model that covers the lawn but not the margin is marked tight rather than ruled out.
Why is a mower tight when its slope limit is above the slope of the lawn?
The sizer wants 5 percentage points to spare. Wet grass and a measuring error eat into a slope limit, so a mower within 5 points of your slope is at its limit. The slope calculator helps you measure the steepest part.
Why is a model missing from the results?
The sizer lists models sold in your region; switch the region in the header to see the others. The data page lists every brand and model in the dataset, and a model it does not list is not in the results yet.
Does a narrow gate rule a mower out?
No. Few makers publish the narrowest passage a mower needs, so the sizer adds a note: a warning when the published width is wider than your gap, a confirmation when it fits, or not published. Check the dimensions in the maker's manual when the gap is tight.
How current are the prices?
Each price is the maker's price in that market, in its currency, with the month we read it. Prices are never converted. Confirm the price on the maker's page before you buy.