Measure the mowing task
Start with a simple sketch of the grass, buildings, beds, driveway and paths. You need the area the mower will maintain, not the total land area on a property listing. Count all grass zones assigned to the same machine, even when they are disconnected.
For rectangular sections, multiply measured length by width. Divide an irregular lawn into smaller rectangles and triangles and add their areas. For a triangle, use base times perpendicular height divided by two. Keep the same units throughout.
If measuring in square feet, divide the total by 43,560 to get acres. For example, 21,780 square feet is half an acre. That is a unit conversion, not a prediction of mower performance. Do not report more precision than your measurements support.
Keep the route beside the area
Make a separate note for each grass section:
- Its approximate area and whether it is connected to the others.
- The path from a possible charging location to that section.
- Narrow gates and the surfaces the machine would need to cross.
- Trees, buildings and other features that might affect navigation.
- Sloped sections and steep boundaries that need manual-specific checks.
Do not subtract a difficult section just because you hope the mower will avoid it. Either include it in the task or decide explicitly that you will maintain it another way.
Use capacity as an initial filter
Compare the total with the manufacturer’s rating for the exact variant. Model-family names often conceal several capacities. A LUBA 3 3000 and 5000 are not interchangeable for a one-acre buyer. The Navimow i215’s smaller rating does not become half an acre by rounding up.
Treat area ratings as a first filter, then check daily schedule, charging, terrain and installation requirements. We do not prescribe a universal extra percentage or assume that two zones double a machine’s allowed area. Confirm any mapping limit with the manufacturer if your total is close to it.
Resolve the costly unknowns first
If two plausible measurements put your lawn on different sides of a product’s capacity limit, measure again before buying. If disconnected areas cannot be joined by a supported route, find out whether manual relocation is allowed and practical.
Passage requirements need the model’s instructions; mower width is not a substitute. Do not infer a safe boundary slope from an advertised hill-climbing maximum. Our guides have not physically tested these routes or machines.
Take your checklist to the shortlist
Use the main robot mower guide to select an appropriate size group. If your measured grass is a full acre, compare the documented one-acre options. Then check navigation requirements before choosing a retailer offer.