Are lawn mower blades universal?

Why blades are model specific

Blades are designed with the mower's deck, motor and airflow. The length must suit the deck, the centre hole and any extra holes must match the mounting, and the lift on the blade's trailing edges creates the airflow that carries grass into the box. A blade from another mower might fit the shaft but cut badly, leave the box half full or, in the worst case, come loose.

What to match

If you are not using an exact part number, these details must all match.

Finding the right part

The easiest route is the part number. It is listed in the manual and on the maker's spares pages, and sometimes stamped on the blade. Search by your mower's model number, which is on a sticker on the deck or body. Third party blades that list your model number exactly can be fine, but check every detail above.

How to sharpen or replace mower blades →

Blade bolts and thread direction

Blade bolts vary. Many have a normal right hand thread, but some mowers use a reverse thread or a special fixing. The manual tells you which way to turn and how tight to make the bolt, sometimes with a torque setting. Do not assume, and never force it the wrong way.

Note:Remove the battery and safety key before touching the blade, wear thick gloves and wedge the blade with a block of wood while you turn the bolt.

Robot mower blades

Robot mowers use small pivoting blades on a disc. They are cheap and are replaced rather than sharpened. Blades vary in thickness and screw type between brands, and some are specific to particular models. Always buy blades listed for your robot and change all of them at once, using new screws if supplied, to keep the disc balanced. Our guide to cleaning and maintaining a robot mower covers how often.

Husqvarna Automower models compared →

Strimmer and hedge trimmer parts

The same principle applies to other tools. Strimmer heads and spools are often brand specific, though line diameter is standardised. Hedge trimmer blades are always model specific. Our explainer on strimmer line sizes covers what is interchangeable.

Checking a blade before you fit it

Before fitting a new or sharpened blade, check it is not bent by laying it on a flat surface. Check it is balanced by hanging it on a nail through the centre hole; if one end drops, file a little from that end. An unbalanced blade vibrates, which wears the motor bearings. When buying a new mower instead, our best cordless lawn mowers guide lists current models with easily available spares from major brands.

Mulching and collecting blades

Some mowers are sold with a standard blade and offer a mulching blade as an option, or the other way round. A mulching blade has extra curves and cutting edges to chop clippings finely. A collecting blade has more lift to push clippings into the box. Using the wrong one does not damage the mower, but the result may disappoint: a mulching blade can make the box fill poorly and a collecting blade mulches less finely.

If you switch between collecting and mulching, check whether your mower needs only a mulching plug or a different blade as well. Our explainer on what mulching does covers the difference.

Frequently asked questions

Can I use any blade on my lawn mower? No. Use the blade made for your model or one that matches length, mounting, shape and rotation exactly.

Are lawn mower blade bolts reverse threaded? Some are, many are not. Check the manual before loosening.

How do I find my mower's blade part number? Look in the manual or on the maker's spares site using the model number from the deck sticker.

Can robot mower blades be sharpened? They are designed to be replaced, not sharpened. Packs are inexpensive.