Robot lawn mowers

Overall score breakdown

We test robot lawn mowers under realistic conditions with common garden features. Our robot lawn mowers test includes cutting performance and ease of use.

Cutting performance

We assess:

• standard lawn cutting

• uneven lawn cutting

• sloped lawn cutting (19°/35% gradient)

• long grass cutting

• damp grass cutting.

We test the robot lawn mowers on a 200m² lawn with two areas connected by a corridor. The lawn comprises mostly well-established dwarf ryegrasses that have been mowed regularly for several years.

The standard test lawn is level and includes a flower-bed, fence, patio and tree.

To prepare for the test, we initially cut the grass to 25mm and remove all grass clippings. We then allow the lawn to grow to 50mm.

Each mower is updated with the latest software before testing begins. The mowers are operated according to the manufacturer's instructions, using default and automatic settings wherever appropriate.

The test runs for 4 weeks. Each week, we adjust the robot lawn mowers’ cutting height, starting at 50mm then reducing by 10mm weekly (or as close to these cutting heights as each mower’s settings allow).

We monitor each robot lawn mower’s performance, including how they handle specific features, such as fences and flower-beds. We record any difficulties, such as the lawn mower getting stuck or stopping. If needed, we fix the problem and restart the mower.

We assess the quality of the lawn finish at the end of each week, including around the flower-bed, fence, patio and tree. We look at overall lawn appearance – including any residual grass clippings (mulching performance) – and the cut’s cleanness and evenness.

In addition to testing the robot lawn mowers on a level lawn, we assess how well they cope with uneven terrain.

We also assess their performance on slopes of 19° (35%) – both in the middle of the sloped area and near the boundary.

Long grass cutting
We allow the grass to grow to approximately 100mm. The aim is to represent what a lawn might be like after a summer holiday or other break from regular mowing. We start each robot lawn mower and leave it to mow until it’s finished the task.

We take note of how long the robot lawn mower takes to complete mowing the area. We also assess the quality of the finish, both immediately after mowing and again after 3 days.

Damp grass cutting
For this part of the test, we set the robot lawn mowers to run when the grass is uniformly damp, like with a heavy dew or after a light rain shower. We water the grass if necessary to maintain consistent conditions.

We record any mower hesitation, stalling or clogging and any excessive build-up of grass clippings.

Ease of use

We assess whether the robot lawn mower comes with full instructions that are easy to follow. We also assess how easy it is to set the boundary for each robot lawn mower. We record how easy it is to install and use the app for each mower. This includes how easy it is to connect the mower to your phone and to programme and monitor the mower.

In addition, we check the method for setting the robot lawn mower’s cutting height. We look at how easy it is to lift, carry and clean each mower. Finally, we check how easy it is to replace the mower’s blades and battery.

Other

We record each robot lawn mower’s specifications, functions and features, including security and safety elements.

Our most important safety test is checking whether a robot lawn mower will stop moving and cutting when we put a fake foot in its path. We apply a penalty to any mower that continues to move forward and cut.

We also inspect and carry each mower to check the robustness of its construction.

We measure how long it takes to charge each mower’s battery and how long it will run (fully charged).

Finally, we measure noise 20cm away from all sides of each mower.