The right lawn mower blade depends on the size of your lawn mower and its model, and the type of cut you’re after. The terrain of your lawn, as well as its size, also plays a big part in deciding the right lawn mower blade.
There is a large variety of blades available in the market, each suited for a specific purpose, so knowing what each type does, along with the application you’re after, is essential.
Lawn mower blades can be classified into four basic types: standard, lift, mulching, and gator. Let’s have a detailed look at each type.
Standard blades are also known as deck blades or medium-lift blades. As the name suggests, this is the blade which often comes attached with new lawn mowers, and is the most commonly used blade.
Both standard and lift blades are referred to as 2-in-1 blades as they do two jobs (discharging and bagging).
The front cutting edge of deck blades is flat, which is why they’re sometimes called straight mower blades. They have a slight curve behind the cutting edge, which produces a continuous cut and suck action. This action provides a great lift in one direction, which makes them ideal for side discharge and bagging purposes.
Standard blades allow clean, precise cutting for a well-maintained lawn. They provide high efficiency in both damp and dry soils. However, they work best on thick patches of grass. They do not trim tall, thin clumps of grass that well, which results in an uneven lawn. Chute blockage is more likely to occur as well.
You may already have a brief idea of what lift blades are from the previous section, as standard blades are, after all, a type of lift blade. Life blades have a slight curve (a “lift”) at the end of a straight cutting edge, which helps provide better air movement for suction.
The height of the curve can vary. Low-lift blades generate the least suction, while high-lift generate the most.
Low-lift blades are appropriate for super sandy and dusty terrains, because the low suction prevents the dust and debris from spreading. However, they cannot trim thick patches of grass that well.
High-lift blades provide neat trimming of very thick and tall grass. The high suction means there’s less chances of chute blockage.
Mulching blades are also called 3-in-1 blades as they can be used to bag, discharge and mulch grass clippings. They’re ideal for those who don’t use a bagger with their lawn mower.
They have a curved surface with an increased cutting edge.
This design kicks up the grass clippings after they have been trimmed so that they can be recut into smaller pieces.
Although mulching blades can be used with a bagger, they won’t provide a powerful lift. Due to their low suction power, they don’t work well on thick, tall grass. Blockages are more likely to occur instead.
Gator blades are an improved mulching blade. They normally have three curved teeth behind the cutting edge, which help generate greater suction, while providing good mulching at the same time.
Does Lawn Size Affect Lawn Mower Blade Size?
In a nutshell, yes, it does. The size of your lawn determines what kind of lawn mower you need, which in turn tells what blade width you require.
For small lawns between 5000 to 1000 square feet, a manual reel or self-propelled mower with 16-inch-wide blades is best suited.
Medium-sized lawns under 20,000 square feet require a self-propelled mower with 20–22-inch blades.
Large lawns that are an acre or more need riding mowers with 42-inch blades. If the lawn is considerably greater than an acre, then 46-inch blades are needed instead.
How Do I Know What Blade Size I Need?
The deck size of your lawn mower will tell what blade size you need.
Can I Use a Bigger or Smaller Blade?
The blade size should be a perfect match with the deck size. Using a bigger or smaller blade can cause damage to the blade, the deck and the user himself.
Mowing time is also significantly reduced by using the correct size blade with the lawn mower.
How Do I Know When to Sharpen or Replace My Lawn Mower Blade?
You know your blade is dull if it pulls on the grass instead of properly trimming and leaves behind jagged edges. Normally, lawn mower blades need to sharpened every 25 hours of runtime; so, once a week.
Typically, blades last around 100 to 200 hours. If you hit stones or sticks during mowing, then the blade might be badly damaged and unsalvageable, and should be replaced as soon as possible.
Can I Use a Universal Blade as Replacement?
Although the lengths may be the same, there are different sized mounting holes, width, thickness etc. which need to be considered as well. If all parameters match, then you can use a universal blade, otherwise no.
How Do I Shop for a Replacement Blade?
You’ll need to measure your blade to find its replacement:
- The length of the blade is measured diagonally from one tip of the blade to the opposite end
- The center hole is of many types: round (inner diameter measured), rounded rectangle (inner length and inner height measured), five-point star, six-point star, seven-point star, and H-pattern. The stars and H-pattern only need to be denoted by their name
- The individual diameters of the outer holes and the distance between them
- The width of the blade needs to be measured at its widest and flattest part, i.e., the center
- The thickness of the blade, which is also measured at its center
Once you have these measurements, you can easily get the correct replacement blade for your lawn mower.
How Do I Find a Replacement Blade Online?
The quickest way is to type in the OEM (Original Equipment Manufacturer) Number with the manufacturer name into a search engine. If you don’t have the OEM Number, then find the model’s name from the given manual to get the needed information.