Perhaps counterintuitively, the setup instructions for your robot lawn mower will likely tell you to start by cutting the grass. Robot mowers mostly can’t deal with long grass. Unlike traditional mowers, these robots don’t collect grass cuttings; they mulch instead, and they are designed to cut frequently, keeping your lawn short and simply leaving the cuttings on the ground, which can also improve lawn health. Most robot mowers are designed to run two or three times a week during the growing season (from late spring to early fall).

They have rechargeable batteries onboard and can last from half an hour to several hours on a full charge. They return to the charging base and recharge automatically when their power runs low. Most mowers have simple controls, a small display, and an emergency stop button. You can generally start and stop mowing, set schedules, and create or edit mapped areas using the onboard controls or the companion mobile app, very much like a robot vacuum.

There are many robot mower features to consider, and the best choice for you depends on what your yard is like.

Lawn Size and Shape

Robot lawn mowers are generally rated to cover a specific square footage, with wider coverage requiring models with larger batteries. Alongside yard size, you should consider the shape and topography of your lawn, as most robot mowers will struggle with steep inclines. While you can often map out separate areas so your robot mower can mow front and back lawns, for example, it will generally need you to lift and carry it between those areas. If you have an uneven garden or steep slopes, you should look for a four-wheel-drive (4WD) or all-wheel-drive (AWD) mower and check the manufacturer’s rating for inclines.

Navigation Type

There are a few types of navigation that robot mowers employ. We’ve tested five different approaches, though some mowers combine multiple technologies for better performance:

• Satellite: Often employing something called Real-Time Kinematic (RTK) Global Positioning System (GPS), these mowers need a satellite signal to navigate and will have a receiver that must be placed in the open with a clear line of sight to the sky. Satellite navigation mowers are not suitable for areas with tall trees or buildings.
• Light Detection and Ranging (LiDAR): This technology sends out rapid laser pulses to 3D map the terrain (it is also used by self-driving cars). It enables mowers to cut grass under thick tree canopies or near tall buildings where GPS signals usually fail.
• Cameras: Cameras and onboard AI are used for obstacle detection and avoidance. AI vision can automatically map areas and cut the grass while avoiding obstacles it encounters, much like how most robot vacuums navigate a home to clean the floors.
• Wire boundary: These mowers require you to install a perimeter wire as a boundary around your lawn that marks out the border the mower should not cross. It’s a messy job that can be tricky.
• Remote control: You mow your lawn from the comfort of your home using a remote controller or an app on your phone. Some only work via remote control, while others can also cut automatically.

Power and Charging

Robot mowers generally come with large charging docks, and you’ll need to earmark a suitable spot for yours. They usually have extensive weatherproof cabling, but you will have to find a route to an outdoor socket.

Wi-Fi and Bluetooth

To connect to your mower and schedule a mow, update the firmware, or remote control it where supported, you need a decent Wi-Fi signal or a Bluetooth connection. It’s best to set up your mower’s charging station within range of your Wi-Fi network. Some mowers also need a strong Wi-Fi signal to operate effectively, so you might consider adding an outdoor mesh router. If you want to connect your phone via Bluetooth, you will have to get quite close.

Most robot mowers are far quieter than their traditional counterparts, and you can expect them to operate at around 55 decibels, though they may go as high as 75 decibels. We only tested battery-powered mowers, but expect gas mowers to be louder. While the operation is often quiet, I did find that several mowers made annoying beeping sounds when backing up or had a loud recorded voice during setup or upon receiving a command.

Robot mowers and their charging stations usually have an IP rating and can cope with rain, but you should pack up and bring your mower indoors during the winter months. Many robot mowers have some kind of rain sensor and will pause mowing when it gets too wet. Some mowers may need to be paused manually. The wheels can churn up your lawn and get caked in mud if mowers continue to labor in the rain, especially with larger and heavier models.

Mowers of different sizes will have varying cutting widths, denoting the width of the strip they can cut on each pass. Most also have floating cutting decks that enable you to choose the length of grass you want (typically 1 to 3 inches). Many robot mowers seem to struggle with cutting around the edges of a lawn, especially if there’s a wall or fence that prevents them from getting close enough.

It’s common to find an uncut verge around the edge of your lawn, so you might need to occasionally get the string trimmer out. Every robot mower I’ve tested has also struggled to cut the area around the charging station, so I recommend placing the unit on a deck or paving if possible.

​Yes, most robot mowers can be installed by anyone, but you might want to set aside an afternoon to work out any snags. Finding the best spot for the receiver for a satellite mower can be tricky. The mapping process can also take a while; usually, it prompts you to remote-control your mower around the border you want to set. After the first mow, you should review its performance and make tweaks to ensure it’s covering the entire area you want to cut.

I test each robot lawn mower for at least a month, on at least two different lawn areas, assessing the ease of setup, the mapping process, automatic scheduling (where available), navigation, obstacle avoidance, and the quality of the final cut, looking for length, uniformity, and any missed patches. Where applicable, I try extra features, tweak settings in the app, and check how the mower handles different weather conditions. I also keep an eye on battery performance and charging time to ensure it aligns with the manufacturer’s claims.