Lawnmowers: How we test lawnmowers

How we decide which lawnmowers to test

Which? tests the best-selling lawnmowers and we also look for newly launched or interesting machines, particularly if they have innovative features.

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Standard lawn test for lawnmowers

Each mower cut a series of 30 sq m test plots

Two experienced testers used each lawnmower to cut a series of 30 sq m test areas of grass, typical of a back-garden lawn with grass around 40-50mm high. 

The lawnmowers were set to cut as close to 25mm (the recommended height for a family lawn) as they could get. We rated each lawnmower for speed, quality of finish and weight of clippings collected. With larger self-propelled petrol mowers we increase the area to 50 sq m.

Tougher lawnmower tests

In addition, we assessed how well each lawnmower coped with less regular tasks:

• Long grass –  the result of leaving it uncut for a summer holiday or the first cut of the spring. We left 30 sq m of standard lawn to grow to 80-100mm, then cut it down to 25mm and rated each lawnmower for speed and ability to cope
• Damp grass –  we tested each lawnmower on 30 sq m of standard-length grass that was wet after a shower or a heavy dew, because sometimes you haven’t got time to let it dry out. We rated each lawnmower for its ability to cope.
• Rough grass, such as a wildflower meadow that’s cut only a couple of times a year, can prove a challenge for lawnmowers. We cut rough grass down from 150-200mm to 60mm or the highest the lawnmower would go, and rated its ability to cope.

‘Bowling green’ lawn test

We also tested how well the lawnmowers coped with a purely ornamental lawn composed of fine lawn grasses and kept short. We cut from 25mm down to as close to 13mm as the lawnmower would go and rated for closeness and neatness.

Tidying up test for lawnmowers

We assessed how closely the lawnmowers could cut to the edge of a lawn, against a border or a fence. The closer they could get, the less we needed to tidy up with a grasstrimmer afterwards.

Lawnmower grass box capacity

We run the mower through standard-length grass until the grass collector is full and weigh the clippings. The more it holds the fewer trips to the compost heap..

Lawnmower ease of use test

Mowers were rated for performance and ease of use

Three testers individually rated each lawnmower on 24 criteria. 

These covered how easy the lawnmowers were to set up ready for use (eg setting the cutting height and handle height), how comfortable the operating position and controls were, how easy it was to push the lawnmower around the lawn and manoeuvre round obstacles, how easy the grass collector was to use and how easily the lawnmower was to clean and store after use.

Fuel efficiency

We measured the volume of petrol used by the larger petrol mowers to cut 100 sq m of our standard test lawn. Those rated 5 stars used less than 100ml, while those rated 3 stars used over 150ml

Testing lawnmowers for very small lawns

For very small lawnmowers, up to a cutting width of 33cm, we've devised an extra test. We set up a 30sq m plot with awkward-shaped beds and borders, a clothes post and raised edges to assess the mowers manoeuvrability. We also skip the rough grass test and put more emphasis on cutting standard grass in our rating. 

 
Testing hand cylinder lawnmowers

We put the hand cylinder lawnmowers through the same test programme we used for powered mowers except we skipped the rough grass test and put more emphasis  on the short grass test when deciding the scores, since cylinder lawnmowers are a good choice for a fine ornamental lawn cut to 12mm or so. We also adapted the ease-of-use ratings to the fewer features on hand cylinder lawnmowers.

More on this...

• Find out how to buy the best lawnmower
• Learn how to cut the perfect lawn
• Subscribe to Which? Gardening magazine