How a mower blade works
A rotary mower blade does two jobs: it cuts the grass, and it moves air. The bent-up section at each end, often called the sail or wing, creates airflow under the deck. That airflow lifts grass upright before it is cut and helps carry clippings out of the deck. The amount of lift a blade creates is what separates most of the common types. The cutting edge sits on the leading side of the blade, and the more a blade is designed for mulching, the more extra cutting surface it tends to have.
Standard (medium-lift) blades
The common default. They have a moderate sail and are typically supplied with many mowers. They are usually described as suitable for regular mowing and side-discharge on ordinary lawns. If your mower already cuts well and you are not changing how you handle clippings, a replacement of the same type is usually sensible.
High-lift blades
These have a steeper, larger sail that creates stronger suction. They are generally suggested for bagging, for thick or lush grass, and for picking up leaves. The stronger airflow needs more engine power and may not suit smaller or less powerful mowers, so check what the manufacturer recommends. In dry, sandy or dusty conditions, strong airflow can throw up more dust.
Low-lift blades
Low-lift blades have a smaller sail and produce less airflow. They are often recommended for sandy or dry ground where high-lift blades can throw up dust and grit, and they can use less power. They are less effective at standing grass up or moving clippings into a bag.
Mulching blades
Mulching blades have a curved shape and extra cutting surface so clippings stay under the deck longer and are cut into smaller pieces that fall back into the lawn. They work best with a mower that has a mulching deck, a mulch plug or a mulch kit, because a deck designed for discharge will let clippings escape before they are chopped. Mulching can be less suitable in very long, wet grass, where clippings can clump.
Gator and serrated blades
Gator-style blades have a serrated or toothed section along part of the blade. They are promoted for chopping leaves and small material more finely, and for heavier mulching in autumn. Gator is a brand name used by one manufacturer, but similar designs are sold by others.
Flat (zero-lift) blades
Flat blades have little or no sail. They produce minimal airflow, which is why they can suit dusty conditions where you want little debris thrown. They do not lift grass or move clippings effectively, so they are often used where bagging is not needed.
Which blade should you choose?
| Your situation | Blade type to consider |
|---|---|
| General mowing, side discharge | Standard (medium-lift) |
| Bagging, thick grass, leaf pickup | High-lift |
| Sandy or dusty ground | Low-lift or flat |
| Leaving fine clippings on the lawn | Mulching, with a suitable deck |
| Chopping leaves and light debris | Gator or serrated mulching blade |
Do I want high-lift or mulching blades?
It depends on what you want done with the clippings. If you bag them, high-lift is the usual choice. If you want to leave them on the lawn, mulching is generally the better fit, as long as your deck supports it. Some mowers are sold as 2-in-1 or 3-in-1 and are designed around specific blades, so check your manual.
Getting the right size
- Use your mower’s model number: this is the most reliable way to find a compatible blade. It is usually on a plate or sticker on the deck or engine.
- Check the blade length: measure from tip to tip of the old blade, in a straight line.
- Check the center hole and bolt pattern: the center hole shape and size must match your mower’s spindle.
- Check the blade thickness and the number of blades: some decks use two or three blades, which have to match the original arrangement.
- Compare against the manual: the manual or the manufacturer’s parts list is the best reference. Aftermarket blades should be listed as compatible with your model.
An incorrectly sized blade can cut poorly, vibrate and may be unsafe.
Sharpening, balancing and safety
Blade handling is a common source of injury, so be careful.
- Prevent starting: disconnect the spark plug lead on petrol mowers, or remove the battery or key on cordless and electric ones, before touching the blade.
- Protect your hands: wear thick gloves and keep your fingers away from the cutting edge.
- Tipping the mower: follow the manual on which side to tip it, since the wrong side can cause fuel or oil to leak.
- Sharpen evenly: remove the same amount of metal from each end so the blade stays balanced. An unbalanced blade can cause vibration, which may damage the mower.
- Replace damaged blades: a blade that is bent, cracked or heavily worn should be replaced rather than repaired.
- Tighten correctly: use the bolt torque and washers specified in the manual.
If you do not feel comfortable removing or sharpening a blade, a mower service shop can do it.
If you also trim edges with powered tools, see our guide to brush cutter blade types. For the rest of your lawn and garden kit, see our overview of long handled garden tools.
Frequently asked questions
What are low-lift mower blades?
They are blades with a small sail that moves less air. They are often used on dry, sandy ground.
What are the best blades for cutting grass?
For most lawns, a standard blade of the type the manufacturer specifies is a sound choice. The best option depends on grass thickness, how you handle clippings and the ground conditions.
How often should I sharpen a mower blade?
Many manufacturers suggest checking the blade at least once a season. A torn, brownish grass tip can suggest the blade has gone dull.