Free tool
Lawn size calculator
Find your garden by postcode, click around the edge of each lawn on the satellite map, and the calculator gives you the area in square metres and the rated area to look for in a robot mower.
2. Outline each lawn
Zoom in, click around the edge of the lawn, then press Finish this area. Repeat for each separate lawn.
3. Your lawn
– m²
No map? Enter measurements instead
How to measure your lawn
- Find your garden. Type your postcode and press Go to postcode. The lookup uses postcodes.io, which returns the rough centre of the postcode, so you may need to pan a little to find your house. You can also zoom and drag the map by hand.
- Zoom right in. The closer you are, the more precisely you can follow the edge of the grass.
- Click around the edge. Each click adds a corner. Use Undo last point if a click lands in the wrong place.
- Press Finish this area. You need at least three points. Repeat for each separate lawn, or for each part of a lawn split by a patio or large bed.
- Read the result. The calculator adds up every area and shows the total in square metres.
What the result means
Alongside the total, the tool suggests a minimum rated area: your lawn plus 20%, rounded up to the nearest 100 m² (never less than 100 m²). It also tells you which size band that falls in: small (up to 600 m²), medium (600–1,500 m²), large (1,500–3,000 m²) or very large (over 3,000 m²).
Use that figure when comparing mowers, not the raw lawn size. A mower rated for exactly your lawn will have to run most days to keep up, and it has no slack for slopes, awkward shapes or a wet May. Our answer on what size robot mower you need explains the reasoning.
From the result you can go straight to the robot mower finder with your area filled in, or see every model rated for your lawn in the full catalogue.
If the map doesn't work for you
Tree canopy, shadows or old imagery can hide the edge of a lawn. In that case, measure it with a tape or by pacing (one adult stride is roughly 0.75–0.8 m), split the lawn into rough rectangles, and enter up to three of them under No map? Enter measurements instead. Round up rather than down.
Frequently asked questions
How accurate is the map measurement?
The maths is accurate to well under 1% for a garden-sized shape, so the result depends on how carefully you click around the edge and how sharp the imagery is where you live. Zoom in as far as the map allows and put points on every corner and curve. Satellite imagery can be a few years old, so check the shape against the lawn you have today.
Why does it suggest a bigger rated area than my lawn?
Manufacturers' rated areas usually assume ideal conditions: a simple, flat lawn and a mower running for most of the day. Slopes, obstacles, narrow sections and fast spring growth all eat into that. Adding 20% headroom gives the mower time to keep up without running every hour it's allowed to.
Should I include flower beds and paths?
No. Only draw the grass the mower will cut. If a bed or patio sits in the middle of the lawn, the simplest approach is to draw the lawn as a few separate areas around it. Separate lawns, such as front and back, should also be drawn as separate areas, because the mower has to be carried or driven between them.
Do you store my postcode or the shape I draw?
No. The postcode lookup goes straight from your browser to postcodes.io, a free public service, and the shape stays in your browser. If you click through to the finder, only the total area and number of areas are passed along in the web address.
Can I use it without the map?
Yes. Open the 'No map? Enter measurements instead' section and type the length and width of up to three rectangular areas in metres. It works without JavaScript and gives the same area and suggested rating.