How steep a slope can a robot mower manage?

It varies a lot, from about 25% on basic models to over 80% on the latest all-wheel-drive machines. The figures are percentages, not degrees, which causes confusion: a 100% slope is 45 degrees, 45% is about 24 degrees and 80% is about 39 degrees.

Typical ranges:

• Two-wheel-drive mowers are commonly rated from about 30% to 50%. The older Segway Navimow i Series (i1) is rated for 30%.
• All-wheel-drive mowers go much further. Mammotion rates the Mammotion LUBA 3 AWD for 80% and Segway Navimow rates the Segway Navimow X4 Series for 84%.

Read the small print. Ratings are maximums, often measured on dry grass, and Navimow's footnote for the X4 says its test was under manual remote control. Some manuals also set a lower limit at the edge of the map than on the open lawn. Wet grass, moss and soft ground all reduce grip.

To measure your own slope, put a straight plank on the steepest part, hold it level, and measure the vertical gap to the ground at the far end. Divide the gap by the plank length and multiply by 100. Choose a mower rated comfortably above the steepest section you want cut. Our slopes guide explains the maths and how drive type affects grip.