How to buy the best line trimmer

Petrol line trimmers

Petrol line trimmers are best for performance and endurance, especially for levelling long grass and weeds. But they’re heavy, noisy, and can be harder to start than other types.

Most petrol line trimmers have 2-stroke motors, which means mixing the right ratio of oil and petrol, and dealing with fumes.

They also require maintenance similar to that of a 2-stroke lawnmower, including checks and occasional replacement of the spark plug and air filter. Four-stroke line trimmers need the engine oil replacing periodically too.

Battery-powered line trimmers

Cordless line trimmers are closing the gap on petrol line trimmers in terms of performance. There are both brushed and brushless motors, with increasingly more brushless line trimmers in the domestic market. Brushless motors generate more torque and speed than brushed ones, delivering more power, and they’re lighter.

Battery-powered line trimmers start with the push of a button or pull of a trigger. You won’t have to yank a start cord, and there’s no choke or primer to worry about, nor fumes. They require very little maintenance compared to petrol models, too. But they’ll only run for a certain amount of time before the battery needs recharging.

Volts (V) indicate the power of a battery – the higher the number, the more powerful. The more powerful cordless line trimmers we’ve tested use 36–60V batteries.

Amp-hours (Ah) indicate a battery’s capacity – the higher the number, the greater the capacity.

The models we’ve tested have batteries of 18–60V and 2.0–5.2Ah with a run-time of 12–40+ minutes.

One-battery systems
Manufacturers of cordless power tools usually market their products as members of a universal battery platform. The idea is you’ll buy your first tool as a kit with a battery and charger, then only need to buy the “skin” (tool only) for subsequent products in the range.

Note that batteries lose capacity over time – both in regular use and in storage – so you’ll eventually need to buy a replacement (usually after a few years). Replacement batteries for some line trimmers can be particularly expensive, so it’s worth checking with the retailer when choosing a model.

Mains-electric (corded) line trimmers

We haven’t recently tested any mains-electric line trimmers, but we continue to monitor the market. Mains-electric trimmers don’t perform as well as cordless models, but they can be an affordable option for tidying patches of grass or weeds in smaller yards.

Line trimmer features

Straight or curved shaft: A curved shaft keeps the line trimmer's cutting head at a good angle for trimming grass and they’re generally easier to use. Straight shafts have longer reach. The shafts of some models are telescopic, making them adjustable to people of different heights.

Handles: Typically, line trimmers have an upper handle on the shaft and lower handle that’s often a loop. Most lower handles can be adjusted by rotating them around the shaft. Some line trimmers instead have handlebar-style (“bike” or “bull”) handles – one on each side of the user, both at the same height. These can ease the load and improve control.

Shoulder harness: Some models come with a harness, which transfers the line trimmer's weight onto your shoulders, preventing your arms from getting so tired.

Balance and weight: Before you buy, hold the line trimmer in the cutting position with your dominant hand on the trigger and the other on the front handle. The weight should feel evenly distributed between the top and bottom of the shaft or a little heavier on top.

Line feed: While some line trimmers have blades for cutting, most use a string-like line. To get more line, they typically use a bump system where you tap the head on the ground. Some use an automatic feed that gives more line when you pull the throttle. But this usually doesn’t work as well as a bump feed. Some basic line trimmers use a manual feed, which requires you to turn off the trimmer to replace the line or plastic blades.

Safety guards: These are mounted on the rear of a line trimmer’s cutting head to protect you from debris. A good guard shouldn't limit your view.

Edging guide: Some models have a wire edging guide to help you make neater edges.

Check our test results to see which line trimmers have the features you want. Then visit your local retailer to see how they feel.