Best Robot Lawn Mower by Yard Size, Slope and Trees

One rated for more than 10,890 sq ft if the lawn has trees or beds. For an open quarter acre a mower rated for exactly 1/4 acre works; with obstacles, step to one rated for about 1/3 acre or more.

RTK-only mowers can lose their satellite fix under heavy canopy. Mowers that add LiDAR or camera vision keep their position, which is why we require one of those for yards with trees.

Most models we list are rated 35 to 50 percent. The all-wheel-drive models go to 60, 80 and 84 percent.

Not with any of these picks. They use RTK, LiDAR or cameras, and you draw the boundaries in the app.

Measure only the grass you want mowed, not the whole lot. One acre is 43,560 sq ft, so 1/4 acre is 10,890 and 1/2 acre is 21,780. A satellite map measuring tool works well; then add 15 percent for an open lawn or 20 to 30 percent for trees and beds before comparing with the rated area.

RTK uses satellites plus a base station and is precise under open sky, so it is the value choice for open lawns. LiDAR maps the yard with a laser and does not depend on a view of the sky, so it keeps working under trees and near tall walls. Many mowers add a camera to either one to spot obstacles.

It varies by model: the Husqvarna 410iQ and 420iQ and the dreame A3 AWD Pro cut 1 to 4 in, the Segway Navimow i215 LiDAR 2 to 4 in, and the Sunseeker S4 and X5 1.6 to 3.2 in. Check that the range covers the height you keep your grass. Robots trim a little often, so they hold a height rather than cut tall grass down.

They are built to stop the blades when lifted or tipped, which the robotic mower safety standard UL 60335-2-107 requires. Still, schedule mowing when children and pets are inside, and clear toys and hoses from the lawn first.

The models in our list that publish a noise rating run 55 to 60 dBA, for example 55 on the Sunseeker V3 and 59 on the Segway Navimow i215 LiDAR. That is quiet enough to mow at night, but check local noise rules and whether night mowing is safe for wildlife.

Yes, if the mower supports multiple zones in its app and can drive between them along a path you set. Add the zones together when comparing with the rated area. An RTK mower needs satellite signal along that path too, so a path under trees or beside the house may need a mower with LiDAR or vision.