Lawn mowers: How we test lawn mowers

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How we decide which lawn mowers to test

At Which? we test the bestselling lawn mowers and also look for newly launched or interesting machines, particularly if they have innovative features. Log in to read our lawn mower reviews or sign up to a £1 trial to Which?

Standard lawn test

Two testers cutting grass with lawnmowers

Each mower cuts a series of 30 sq m plots

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

The lawn mowers are set to cut as close to 25mm (the recommended height for a family lawn) as they can get. We rate each one for speed, quality of finish and weight of clippings collected. For larger self-propelled petrol mowers, the test area is increased to 50sq m.

Tougher lawn mower tests

In addition, we assess how well each lawn mower copes with less regular tasks:

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

‘Bowling green’ lawn test

We also test how well the lawn mowers cope 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 lawn mower will go and rate for closeness and neatness.

Tidying up test 

We assess how closely the lawn mowers can cut to the edge of a lawn, against a border or a fence. The closer they can get, the less you need to tidy up with a grass trimmer afterwards.

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.

Ease of use

A picture of two testers on a lawn

Mowers are rated for performance and ease of use

Three testers individually rate each lawn mower on 24 criteria. 

These cover how easy the lawn mowers are to set up ready for use (eg setting the cutting height and handle height); how comfortable the operating position and controls are; how easy it is to push the lawn mower around the lawn and manoeuvre round obstacles; how easy the grass collector is to use, and how easily the mower is to clean and store after use.

Fuel efficiency

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

Testing lawn mowers for very small lawns

For very small lawn mowers, 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 when deciding the scores. 

Cylinder mowers

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

Total test score

The final score is a combination of ratings across all the tests, with 60% allocated to how the lawn mower cuts and 40% to ease of use.

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