- The battery, not the brand on the handle, decides whether a cordless mower finishes your lawn, so check the runtime, the charge time and whether you can replace the battery before you look at anything else.
- Match the cutting width to the size of your lawn: 30cm to 34cm for a small lawn under 50 square metres, 35cm to 40cm up to 150 square metres, and more than 40cm beyond that.
- A cordless mower is the wrong tool for a very large, steep or often-soaked lawn, and knowing that before you pay saves you a mower that cannot cope and a battery that dies halfway.
The Mower That Dies Halfway Across the Lawn Was Chosen Wrong, Not Built Wrong
A cordless mower that runs flat with a third of the grass still standing is the most common complaint people have about them, and it is almost always a buying mistake rather than a fault. The mower was never matched to the lawn. Pick the wrong battery, the wrong cutting width or the wrong type for your ground, and no amount of careful mowing rescues the afternoon.
Get the choice right and a battery mower is a joy: no cord to slice through, no petrol to go stale over winter, no pull cord to yank, and quiet enough that you can cut the grass early on a Sunday without a neighbour appearing at the fence. The trick is to check a short list of things before you hand over any money, and to judge the mower on the parts that actually matter rather than the colour or the badge.
Which?, which runs independent tests on garden kit, puts the testing like this, in the words of researcher Natalie Brown: “We test all of our mowers on multiple different grass types grown specifically for lawn mower testing.” You do not have a test lab, but you can check the same specifications they do. Here is what to look at, and what each number means once you strip out the marketing.
Match the Cutting Width to the Size of Your Lawn
The cutting width is how wide a strip the mower cuts in one pass, and it is the spec most people ignore and later regret. Too narrow and a big lawn takes forever, as every strip is thinner and you walk the lawn more times to finish it. Too wide and you cannot steer the thing around flower beds, tight corners and garden furniture without leaving uncut tufts. The right width is set by the size of your lawn, not by what looks powerful in the shop.
As a working guide, a small lawn under 50 square metres (about 540 square feet, or a strip roughly 7m by 7m) suits a cutting width of 30cm to 34cm (12in to 13.5in). A medium lawn of 50 to 150 square metres (540 to 1,600 square feet) wants 35cm to 40cm (14in to 16in). A large lawn over 150 square metres (1,600 square feet) needs more than 40cm (16in) to finish in a reasonable time. Pace out your lawn before you shop. Two minutes with a tape saves you a mower that is either a chore to push or a nightmare to steer.
The Battery Is the Part That Decides Everything
The battery is where a cordless mower is won or lost, and it hides behind two numbers worth learning. Voltage, written as 18V or 36V, is a rough guide to power: higher voltage drives the blade harder through thick or damp grass. Amp-hours, written as 2.0Ah or 4.0Ah, is the size of the fuel tank: more amp-hours mean the mower runs for longer on a charge. A mower that pairs a big voltage with a small amp-hour battery has plenty of punch and no stamina, which is exactly the one that dies halfway across the lawn.
Check the real runtime, not just the battery size. A good cordless mower cuts for more than 30 minutes on a charge. A weak one runs out inside 20. Check the charge time too, as there is a wide gulf here: around an hour is good, while some take more than six hours to fill, which turns a quick top-up into a wasted morning. If your lawn needs longer than one charge, a second battery on a fast charger lets you swap and keep going.
The most important check of all is whether the battery can be replaced. The single most common way a cordless mower dies is its battery wearing out, and if that battery is sealed in or already discontinued, the whole mower goes in the skip with it. Buy a model with a removable, replaceable battery from a range the maker still sells. It is worth buying a spare at the same time, as manufacturers drop old battery formats surprisingly fast, and a spare is usually cheaper bought alongside the mower than on its own later. A spare battery runs anywhere from about 30 to 80 pounds (roughly 40 to 105 US dollars) depending on the amp-hours.
One trick saves real money here. Several brands, Einhell’s Power X-Change range among them, build one battery that fits the mower, the hedge trimmer, the drill and the rest of the range. If you already own a cordless tool from such a brand, a bare mower that takes the same battery costs far less than a full kit, and you are not paying twice for batteries you already have. On price, a capable cordless mower with battery and charger typically runs 350 to 500 pounds (about 450 to 650 US dollars), though a small entry model for a tiny lawn can be found from around 150 pounds (roughly 195 US dollars). Watch that the battery and charger are in the price, as they are sometimes sold apart.
Cutting Height, Drive and the Bits That Save Your Back
Check how the mower changes its cutting height. The best designs lift the whole deck with a single lever, so you can raise the cut in seconds. Cheaper ones make you adjust each wheel separately or add and remove spacers, which is fiddly enough that most people never bother and leave the grass at one height all year. That is worth avoiding, as you want the grass longer at the start of the season and in dry spells to protect it from stress, and a touch shorter in summer for a tidy finish. A mower you cannot easily adjust is a mower stuck on one setting.
Decide whether you need drive on the wheels. A self-propelled mower uses the motor to pull itself along, which is a real help on a large or sloping lawn and far less so on a small flat one, where it is extra cost and extra heft for no gain. Front-wheel drive suits a flat lawn with lots of obstacles, as you can lift the front to turn. Rear-wheel drive grips better on slopes and uneven ground. A variable-speed control that matches the mower to your walking pace is worth having if you go self-propelled. On a small, level lawn, skip drive altogether and save the money.
Then the small things that decide whether you enjoy using it. Cordless mowers are heavier than corded electric ones, though lighter than petrol, so lift one in the shop if you will carry it up steps or hang it on a wall. Check the handle height suits you and whether it folds for storage. Think about how you want the clippings handled: a grass box you empty, or a mulching mower that chops clippings fine and drops them back to feed the lawn, saving you the trips to the compost heap. Grass combs or inset wheels help you cut right up to a lawn edge without a second pass with the shears.
When a Cordless Mower Is the Wrong Call
A cordless mower is not right for every lawn, and spotting that before you buy is the cheapest decision of all. A very large lawn, well beyond 150 square metres, can outrun even two batteries, and a corded electric or petrol mower keeps going without a recharge. Long, wet or rough grass drains a battery fast and bogs a light cordless mower down, so if your ground is often soaked or you let the grass get away from you, a sturdier machine earns its keep. Steep banks and slopes ask more of a motor than a modest battery mower likes to give.
For a small to medium lawn that you keep on top of, though, a cordless mower is hard to beat, and it is kinder on the ears for you, your neighbours and the wildlife at the bottom of the garden. Buy on runtime, charge time and a replaceable battery, match the cutting width to your lawn, and skip the features your ground does not need. Do that and the mower finishes the job on one charge, year after year, instead of stranding you in the middle of the lawn with a dead battery and half a job done.
For more on getting the most from the mower once it is home, see our guides to sharpening a blade that tears the grass and putting a mower away for winter so it starts first time.
