Manufacturers state a maximum area (in acres or m²). Treat it as an upper bound, not a target: a mower rated for 0.25 acre running near its limit will mow almost continuously and wear faster. Also count only the area the mower can actually reach — narrow passages and fenced-off sections add complexity, not just square metres.
Four approaches dominate. Boundary wire is the oldest and cheapest: a physical loop defines the area. RTK uses a satellite reference station and is accurate but needs a clear view of the sky. LiDAR measures distances with laser scanning and works under trees. Camera/vision systems recognise grass edges visually and need reasonable lighting.
Check the stated maximum slope (often given as a percentage or degrees). British gardens with banks, roots or uneven ground need a model with a higher slope rating and preferably all-wheel drive.
Robot mowers are quiet compared with petrol mowers, but they run for hours and often at night. Check the dB figure if you have close neighbours, and use the scheduling function to avoid early morning and late evening runs.
Most use small pivoting blades on a disc rather than a cylinder. Blades are consumables — budget for replacement sets each season. Check whether spares are stocked for your model in the UK.
App control is standard; some models use 4G or GPS tracking. Check the warranty length, whether service is UK-based, and whether winter storage and battery care are covered in the manual.