How we test lawn mowers

We've been field testing lawn mowers for decades, so we know what separates the best corded electric, cordless battery and petrol mowers from the rest.

Today, we test around 30 lawn mowers a year. We carry out around 200 different checks and assessments on every single one to separate the outstanding models from the poor mowers that aren't worth your money.

We buy our lawn mowers directly from retailers, which not only prevents manufacturers from influencing our reviews, but it also ensures we test exactly the same standard of mower that you would buy. Reviews you read elsewhere might be based solely on a single user’s initial impressions, rather than the thorough, independent field tests and assessments carried out at Which?. 

Go straight to our best lawn mowers guide to find out the top-scoring models from our tests

Watch: how we test lawn mowers

Watch our video to learn more about the key elements of our independent, scientific test programme and what we look for in a lawn mower.

Grass-cutting ability: how well will it mow my lawn?

We test each different type of lawn mower on a range of grass, from a short, ornamental lawn to rough meadow grass.

We measure how much time and effort it takes to mow a lawn, and how closely the mower cuts up to the edges to reach tricky bits of longer grass. 

That's not all. We also assess how easy each petrol mower is to start, both from cold and after it's been running for a while. Plus, we check it's got enough power to cut through long grass and tough, clumpy meadow grass.

What separates a good result from a poor one?

A five-star mower cuts all types of grass well in all conditions, and leaves a nice neat finish. A three-star machine might struggle on lower settings, especially if the grass is long, and may be less well suited to tougher tasks.

Natalie Brown, Which? lawn mower expert, says:

'Depending on where the wheels are and how manoeuvrable a lawn mower is, it might be able to cut grass lying flat over lawn edges or growing up against a wall or fence – or it might leave you reaching for your strimmer.' 

Handling difficult terrain: will the lawn mower be able to cope with tough mowing jobs?

We test each mower on uneven and sloping ground, along lawn edges and close to walls before giving it an overall star rating. Each mower also edges 90 metres of lawn against a wall and across a flower border. 

Our tests assess how closely the mowers cut grass that's been left to grow along paths and borders, and around trees and walls. We use each lawn mower on 15 metres of each type of edging and rate the finish. 

What separates a good result from a poor one?

A five-star mower gives an excellent finish on uneven surfaces, and won't leave you having to finish edges with a strimmer or by hand. A three-star mower can't handle these surfaces well and might struggle close to walls and fences. We’ve found some lawn mowers that leave you with up to 5cm of uncut grass.

Grass collection: will the lawn mower collect all my grass clippings?

We assess how full the grass collector gets before it needs emptying (yes, we actually weigh it!) and how often we have to empty it to complete our cutting tests.  

What separates a good result from a poor one?

Some models collect all the clippings, but others leave clumps of grass on your lawn or scatter the clippings far and wide. Check the star ratings in the test results section of our lawn mower reviews to see how different models compare.

Ease of use: is the lawn mower straightforward to use?

Our ease-of-use tests cover how easy the lawn mower is to set up ready for use (including setting the cutting height and handle height), how comfortable the operating position and controls are, how easy it is to push the mower around the lawn and manoeuvre around obstacles, how easy the grass collector is to use, and how easy the mower is to clean and store after use.

We also weigh each lawn mower so we can tell you how heavy it will be to lug around, and note other essentials such as the cable length on corded electric models.

What separates a good result from a poor one?

A machine with three stars for ease of use might have niggles such as foldable handles with wingnuts you need to loosen first, or multiple levers to change the cutting height. A five-star mower will be simple and easy to use and manoeuvre, and take the hard work out of cutting your grass.

Quietness: how noisy is it?

We monitor the noise levels when the mower is in use and give it a rating based on how quietly it runs.

What separates a good result from a poor one?

If a mower is fairly quiet for its size, you know you won't annoy your neighbours if you decide to cut the grass first thing. If it's noisier than most, we'll tell you.

Battery life: how long does it last?

We test how long the battery lasts after a full charge, how much ground the mower can cover on a full charge, and how long it takes to fully charge the battery or batteries.

Lithium-ion batteries always get depleted over time and eventually die. At Which?, we believe that cordless products should last longer than the batteries they come with. That's why we no longer make cordless lawn mowers Best Buys if spare batteries aren't available from the manufacturer – no matter how good the lawn mower might be.

What separates a good result from a poor one?

The best cordless mower batteries usually last 30 minutes or longer, but some manage only half that. We tell you the battery life in our reviews, so you know whether the mower will last long enough to cut your lawn on a single charge.

Energy efficiency: how does energy consumption compare with other mowers?

We find out how much of an impact mowers will have on your bills by measuring how much electricity or fuel they use when mowing our test lawns.

For corded electric and cordless mowers, we measure the exact amount of energy required to complete specific mowing tasks. We also record the energy required to charge the battery.

For petrol models, we measure fuel usage relative to the total area cut to determine running costs.

What separates a good result from a poor one?

A four or five-star rating means the mower uses minimal energy or fuel to cut a given area of grass. Electric mowers with brushless motor technology often achieve this result. Inefficient mowers use excessive electricity or fuel to carry out basic cutting tasks.

How we calculate the scores

Dr Steph Kipling, Which? science team manager and lawn mowers scientific adviser, says:

'We regularly ask Which? members what matters most about their lawn mowers. I then use this information when developing our test programme to make sure we replicate how consumers use their lawn mowers at home. When creating our scoring system, I also ensure the most important aspects have the highest impact on the score we give each product we test.'

Each of the assessments described above contributes to the total test score, which is the percentage figure we award each lawn mower. But certain assessments are more important than others, and so carry different weights:

Cordless lawn mowers:

• 50% Grass cutting ability
• 30% Ease of use
• 5% Quality of features
• 5% Battery life
• 5% Noise
• 5% Energy consumption

All other lawn mower types:

• 51% Grass cutting ability
• 31% Ease of use
• 6% Quality of features
• 6% Noise
• 6% Energy consumption

How we choose the products

To make sure our reviews are 100% independent, we never accept free product samples from manufacturers or brands. Instead, we invest nearly £10,000 every year buying lawn mowers directly from major retailers.

We also cater to a range of budgets, from less than £100 to more than £1,000. Everything from basic, no-frills mowers to all-singing, all-dancing machines will make their way through our test lab in any given year. This means we can showcase premium Best Buy models alongside Great Value machines that punch above their price.  

Cherie Cheung, Which? market analyst, says:

'My role is to ensure we're selecting all the key lawn mower models for testing that will be most relevant and interesting to consumers. I attend press events and product showcases to get hands-on with products, be it a new cordless range or a sturdy corded model. Keeping in touch with manufacturers also helps me stay prepared and get updated on the newest launches, so we can be ready to test, review and let you know which models make the cut as soon as we can.'

Is it a Best Buy lawn mower? What our verdicts mean

Best Buy-recommended lawn mowers

Best Buys typically do well in most, if not all, of our tests, and our Best Buy recommendation factors in the pros and cons of each type of mower.

We use different Best Buy cut-off points for each type of mower to account for the differences between the power sources.

Great Value-recommended lawn mowers

If you're after a great lawn mower but want to keep costs down, our Great Value recommendation is for you.

To be recommended as a Great Value lawn mower, a model must be markedly cheaper than the average price for tested models of the same type, and be good at the all-important tasks of cutting and collecting grass.

Eco Buy-recommended lawn mowers

Eco Buy lawn mowers will have a lower impact on the environment over their lifetimes than other mowers. 

We calculate this by looking at how reliable the manufacturer is and how easy the mower is to maintain, which gives us an idea of how long-lasting it’s likely to be. We also look at how energy efficient it is, as well as its battery life. 

To earn our Eco Buy badge, a lawn mower must:

• have a total test score of at least 70%
• be an electric model – either corded or cordless, but not powered by petrol. 
• get four stars and above for grass-cutting ability
• get four stars and above for energy efficiency
• get four stars and above for battery life (cordless models only)
• get three stars and above for noise ratings to minimise noise pollution and the disruption of local ecosystems
• be from a brand that gets a good reliability rating in our annual lawn mower owners survey
• satisfy us with its build quality and ease of maintenance in our expert assessments.

Only 5-10% of lawnmowers are sustainable and effective enough to be Eco Buys. To find out which qualify, head to our Eco Buy lawn mower reviews.  

Don't Buy lawn mowers

Lawn mowers that score 45% or below are highlighted as Don't Buy models we think you should avoid.

Discover which models impressed in our lab in our lawn mower reviews – use the Best Buy, Eco Buy and Great Value filters to help find the right model for you

What is the future for petrol-powered lawn mowers? 

With sales of new petrol and diesel cars to be banned by 2030, could petrol gardening tools be next?

By improving the appearance of outside spaces, we may be inadvertently contributing to environmental damage.

Unlike cars, petrol mowers don’t have catalytic converters to reduce the amount of pollutants that enter the atmosphere. This is likely due to the cost of materials bumping up the retail price, and because UK regulations are less strict for garden tools.

Over in California, the sale of petrol gardening equipment has already been banned.

We're already seeing fewer petrol launches from manufacturers, which appear to be focusing on cordless tools. These produce zero emissions and are quieter, offering a better option for both the environment and our health.

We’re finding that cordless tools now rival petrol in power and, in some cases, outperform them, so many consumers have already switched.

Our lawn mower experts

Running our lawn mower tests is a group effort, with several team members contributing to each one. 

We thoroughly re-evaluate our testing processes every year to ensure they're useful to you, and we ask the Which? community to tell us what matters the most when choosing a new lawn mower.

Here's the team that makes it happen:

• Senior researcher & writer, Natalie Brown: Natalie translates technical laboratory data into in-depth, unbiased product reviews and advice to separate the best lawn mowers from the machines that struggle. She cuts through the marketing hype to ensure you invest in a mower that's good at cutting all types of grass and gives a smart finish with minimum fuss.
• Gardening editor, Ceri Thomas: Ceri studied horticulture at university and has spent her career editing gardening content. She makes sure what you're reading is exactly what you want to know about lawn mowers. This means keeping a close eye on what's trending, seeking out key consumer questions we can help answer and finding new stories from our data to help empower our readers. 
• Science team manager, Dr Steph Kipling: Steph plays a key role in shaping our test programme, and meticulously converts hundreds of data points for each lawn mower into easy-to-understand product scores and star ratings. Her rigorous analysis ensures that only the cream of the crop get our Best Buy, Great Value and Eco Buy badges. 
• Market analyst, Cherie Cheung: It's Cherie's job to select the key lawn mower models for testing and curate our testing line-up, ensuring we only review what’s relevant to you. From well-known brands to new entrants, we look beyond the marketing hype to test what you want to buy next.