How to measure your lawn for a robot mower (m², square feet and acres)
Measure the grass you actually mow, convert between square meters, square feet and acres, and choose a mower with the right headroom.
The quick answer
Measure only the grass the mower will cut, not your whole plot. Split the lawn into simple rectangles and triangles, measure each, add them up, and subtract beds, patios and other areas the mower will not cross. Then choose a mower rated comfortably above that figure, especially if the lawn is split into several areas, has narrow passages or grows quickly in summer.
Lawn area converter
Enter the lawn’s length and width, or a total area.
Why the number on the box is not your plot size
Robot mowers are rated by the area of grass they can keep tidy, usually in square meters or acres. Property listings and maps give the size of the whole plot, including the house, driveway, beds and patio. Buying from the plot size typically overestimates what you need; buying from a guess can leave you with a mower that never quite keeps up.
Measure it in four steps
- Sketch the lawn and divide it into simple shapes: rectangles, squares and triangles.
- Measure each shape with a tape or a measuring wheel. For a rectangle, area is length times width. For a triangle, half of base times height.
- Add the shapes together, then subtract any beds, trees, ponds or paving inside the lawn.
- Write down each separate area and the narrowest connection between them; the mower needs a route.
Online map tools with an area measurement feature give a quick cross-check. Trace only the grass, not the plot boundary.
Converting between units
| Area | Square meters | Square feet |
|---|---|---|
| 0.1 acre | 405 m² | 4,356 sq ft |
| 0.15 acre | 607 m² | 6,534 sq ft |
| 0.25 acre | 1,012 m² | 10,890 sq ft |
| 0.5 acre | 2,023 m² | 21,780 sq ft |
| 0.75 acre | 3,035 m² | 32,670 sq ft |
| 1 acre | 4,047 m² | 43,560 sq ft |
One square meter is about 10.76 square feet, and one acre is 43,560 square feet or about 4,047 square meters. The converter on this page handles any figure.
How much headroom to allow
A mower’s rating assumes a reasonably simple lawn. Several separate zones, long narrow strips, lots of obstacles and fast spring growth all mean more time per square meter. As a rule of thumb, choose a model whose rated area is at least 20 to 30% above your measured grass if your lawn is complex, and do not buy at the exact limit.
Also check how much a model covers per charge and per hour. A mower that needs several charge cycles for your lawn is fine on a daily schedule but will struggle to catch up after a wet week.
Your questions, answered.
How many square meters is a quarter acre?
About 1,012 m², or 10,890 square feet.
Should I include flower beds when measuring my lawn?
No. Measure only the grass the mower will cut, and subtract beds, patios and other features inside the lawn.
What size robot mower do I need?
One rated comfortably above your measured grass area, with extra headroom for multiple zones, narrow passages or fast growth.
How do I measure an irregular lawn?
Divide it into rectangles and triangles, measure each, and add them up. A measuring wheel or a map tool’s area feature makes it quicker.
Ready to choose?
Robots we recommend in robot lawn mowers
See all
Mammotion LUBA 2 AWD
All-wheel drive for a more hands-off lawn.
Best for Uneven lawns and multi-zone gardens
Read the review
Segway Navimow i105
A considered starting point for smaller lawns.
Best for Smaller lawns within its rated coverage
Read the review
Sunseeker X3 Plus
Wire-free mowing for a more manageable weekend.
Best for Suburban lawns up to 0.3 acre with suitable navigation and dock placement
Read the review