How to determine the size of the lawn area for the robotic lawnmower?

The most important key figure of a robotic lawnmower is the area output. If this does not match the actual lawn area, the robotic lawnmower may not be able to mow the entire area in the specified time. The result: The lawn is not perfect and unevenly cut. So how do you correctly determine the area for the robotic lawnmower?

Manufacturers of robotic mowers specify the area output for individual models. This tells you what area your device can mow in a certain time under ideal conditions. Perfect cutting results can only be achieved if the specified performance matches your garden. How do you find out how large the area of your own garden actually is?

The size of your own garden is important for selecting a suitable robotic lawnmower model. However, the calculation is not always very simple. The first variant works classically by calculating individual areas:

Common lawn shapes and their formulas for calculation

Shape Formula Shape
Rectangle a x b rechteck
Square a2 quadrat
Right-angle triangle a x b / 2 dreieck
Obtuse triangle a x b / 2 dreieck
Convex square (a x h1 / 2) + (a x h2 /2) Konvexes Viereck
Rhombus a x b Raute mit gleich
Rhomboid a x b Raute mit gleich
Trapezoid (a + c) / 2 x h Trapez
Right-angle trapezoid (a + b) / 2 x c Rechtwinkliges Trapez
Semi-circle π x r² / 2 Halbkreis
Circle π x r² Kreis
L-Shape (a x b) + (c x d) L-Form
U-Shape (2 x (a x b)) + (c x d) U-Form

Of course, not every garden has an ideal shape, so it may be necessary to divide the garden into individual areas. This works best if you make a sketch of the garden first.

Calculate lawn area with Google

It is easier and faster to calculate your lawn area with Google Maps. With the range finder, the tool offers a really handy way to measure your own plot.

  • First, enter the desired address in Google Maps.
  • Right-click on a point at a corner of the property and select "Measure distance".
  • Now click once around the lawn. To make the line more precise, you can also add more points afterwards.
  • Finally, you can easily read the result. In addition to the circled area, the distance is also displayed. This is particularly useful for directly determining the approximate length of the boundary wire required.

The area output of the robotic lawnmower - suitable for the lawn area

Manufacturers initially specify the maximum area output for robotic mowers. This value indicates how much area the device can mow in a certain time under absolutely optimal conditions. In practice, however, these conditions are rarely achieved as factors such as complex garden layouts, slopes, weather conditions or even the type of lawn influence  mowing times.

Accordingly, there is a second value with the recommended area output, which is significantly below the maximum performance but in many cases corresponds to reality.
If you want to determine which area output the robotic lawnmower needs to mow your lawn in a desired mowing time, proceed as follows:

  • Determine the weekly operating time of your robot in hours. For example, if this is 6 a day, but Sunday is excluded, you will arrive at 36 hours a week.
  • Determine how many hours the robotic lawnmower should be in use according to the manufacturer in order to achieve the specified mowing output.
  • Calculate the lawn area of your yard.
  • Put the numbers into the following formula:

Lawn area in m² / planned mowing time in hours x assumed mowing time of the manufacturer = required area output (according to the manufacturer).

In the above example, this would make the calculation as follows:

1,250 m² / 36 hrs. x 120 hrs. = 4,166.67 m²

For an area of 1,250 m², you would therefore need a robotic lawnmower with an area output of around 4,200 m² if the robotic lawnmower is only to be used 6 hours a day.

Important terms when determining the area performance

In addition to the area output, there are other key figures that are important for the overall performance of the robotic lawnmower:

  • maximum operating hours per day. This figure tells the maximum time the robotic lawnmower can spend on the lawn per day minus charging times.
  • mowing capacity as area output per hour
  • mowing cycle: During this time, the device mows the entire lawn once.
  • cutting width: The larger the cutting width, the larger the area the robot can mow with each pass, i.e. the more efficient the device is.
  • battery run time: the larger the battery, the longer the mowing time. This also shortens the total time it takes to mow the entire area once.
  • mowing speed: the speed of the robotic lawnmower in km/h.

Calculating the lawn area is an indispensable requirement when purchasing a suitable robotic lawnmower. An even cut is ensured only if the model is powerful enough to mow your lawn in the desired time.