How to choose a lawn mower: cordless, electric, petrol or robot
Start with the size of your lawn. That decides the cutting width and, in most gardens, whether cordless is enough. Everything else is about comfort and finish.
The short answer
Small lawn (up to about 150m²): a corded electric or small cordless mower with a 30–34cm cut.
Medium lawn (about 150–400m²): a cordless mower with a 36–42cm cut. This suits most UK gardens.
Large lawn (400m² and up): a bigger cordless mower with two batteries, or a petrol mower with a 46cm+ cut, ideally self-propelled. Consider a robot mower if you'd rather not mow at all, and a ride-on for very large areas.
Measure your lawn first
Pace out the length and width of your lawn and multiply them. A typical small terrace lawn is under 100m²; many semi-detached gardens are 150–300m².
| Lawn size | Cutting width | Good choices |
|---|---|---|
| Up to about 150m² | 30–34cm | Corded electric, small cordless, manual cylinder |
| About 150–400m² | 36–42cm | Cordless (one or two batteries), corded if a socket is close |
| About 400–800m² | 42–53cm | Larger cordless with two batteries, petrol, self-propelled |
| Over about 800m² | 50cm+ or ride-on | Petrol self-propelled, ride-on, robot |
These are rough bands. A long, narrow lawn or one broken up by beds takes longer than its area suggests, so lean towards the narrower width if you have lots of corners.
The four kinds of mower
Corded electric mowers are light, cheap and never run out of charge. The cable is the catch: it limits how far you can go from the socket and has to be kept away from the blade. Best for small, simple lawns near the house. Always plug in through an RCD.
Cordless (battery) mowers have taken over most of the market. They're quiet, start instantly, need almost no maintenance and fold away. Runtime is the limit: makers quote how many square metres one charge will cut, and it falls in long or wet grass. A second battery solves most problems. If you already own cordless tools, buying into the same battery range saves money.
Petrol mowers still suit large lawns and rough grass. They run as long as there's fuel, cope with long grass and are usually wider. In return they are noisy, heavier and need servicing, fresh fuel and oil. A self-propelled petrol mower drives its own wheels and makes a big lawn far less tiring.
Robot mowers cut a little every day on a schedule, leaving fine clippings that feed the lawn. Older and cheaper models need a boundary wire pegged around the edge; many newer ones navigate without a wire using satellite positioning or cameras. Check the maximum lawn area and slope the model handles, and how it copes with narrow passages between lawns.
Rotary or cylinder?
Almost all mowers sold are rotary: a single blade spins horizontally under the deck. They handle longer, uneven grass and suit most lawns.
Cylinder mowers cut with a spinning set of blades against a fixed bottom blade, like scissors. They give the finest, closest finish and the best stripes, but need a flat, well-kept lawn and frequent cutting. Choose one only if a bowling-green finish is the aim.
Features worth paying for
- Rear roller. Gives stripes and lets you cut right up to the edge of a lawn that meets a path.
- Grass box size. Bigger boxes mean fewer trips to empty them on a large lawn. A full-box indicator helps.
- Easy height adjustment. A single lever is far easier than moving each wheel.
- Mulching. Chops clippings finely and returns them to the lawn instead of collecting them.
- Folding handles and vertical storage. Matter more than you think in a small shed.
- Weight. Worth checking if you have steps to carry it up or down.
- Battery platform (cordless). One battery that fits the mower, hedge trimmer and strimmer is cheaper and simpler.
Batteries: what the numbers mean
Voltage (18V, 36V, 40V and so on) is roughly power: higher-voltage mowers cope better with thick, long or damp grass. Some 36V mowers run on two 18V batteries at once. Amp-hours (Ah) is capacity: a 5Ah battery runs about twice as long as a 2.5Ah one of the same voltage. For a medium lawn, check the maker's quoted area per charge against your lawn, with some spare.
Which should you buy?
- Small, simple lawn near a socket: corded electric, or a small cordless if the cable annoys you.
- Most gardens: a cordless mower with a 36–42cm cut and two batteries, or one large battery.
- Large or rough lawn: a self-propelled petrol mower, or a large cordless with two batteries.
- No time or inclination to mow: a robot mower, run in daylight only.
- Perfect stripes on a flat lawn: a cylinder mower with a rear roller.
Questions people ask
What size lawn mower do I need?
Roughly: up to 150m² needs a 30–34cm cut; 150–400m² suits 36–42cm; 400–800m² suits 42–53cm; anything larger suits a 50cm+ petrol, ride-on or robot mower.
Is a cordless lawn mower as good as petrol?
For most UK lawns, yes. Cordless mowers are quieter, lighter and need almost no maintenance. Petrol still has the edge on very large lawns and long, rough grass, where battery runtime runs short.
How long does a lawn mower battery last?
It depends on the battery size and the grass. Makers quote the area one charge will cut; long or wet grass reduces it. A second battery is the simplest way to finish a bigger lawn in one go.
Do robot lawn mowers need a boundary wire?
Older and cheaper models do. Many newer robot mowers work without a wire, using satellite positioning or cameras to map the lawn. Check the model's maximum area and slope.
Rotary or cylinder lawn mower?
Rotary for most lawns: they handle longer, uneven grass. Cylinder mowers give a finer finish and better stripes but need a flat, well-kept lawn and frequent cutting.