Which Side of the Lawn Mower Blade is Up

Which Side of the Lawn Mower Blade is Up Image

Lawnmowers make lawn care easier and give you much control over the lawn and yard. But you must care for the mowers to keep them working as desired.

A crucial part of caring for your lawnmower is sharpening the blades or replacing them once they’re worn out.

Both processes often involve removing and reinstalling the blades, so you must know the correct lawn mower blade position.

Without knowing which side of the lawn mower blade is up, you could end up messing your lawn by installing the blades incorrectly.

Do lawn mower blades turn clockwise or counterclockwise? Getting this answer correct is a key step in determining the correct lawnmower blade orientation.

Which Side of the Lawn Mower Blade Is Up?

The dull side of the lawnmower blade is up, with the sharp side slightly lower towards the ground. Lawnmower blades are designed to have the sharp side facing the ground and the dull side facing up to facilitate easier grass cutting–except for a reel lawnmower.

You may be unsure which side is sharp and which side is dull. In such a case, study the blade to see which side is raised toward the deck (up); the opposite side (facing down) will be the sharp, grass side.

How to know if the mower blade is upside down?

Lawnmower blades are designed to cut on one side, in one direction, depending on the mower’s design.

Your model could turn clockwise or counterclockwise when cutting. So you need to know how to determine the correct lawn mower blade position to reinstall one correctly when sharpening or replacing a worn blade.

Here are the rules to guide you in deciding which side of the lawn mower blade is up.

1. Study the owner’s manual

Your mower’s manual contains every piece of information you may need to understand, operate or service the machine. This information includes details of the blade orientation.

The manual should help indicate which side of the cutting blade is the grass side and which side is the deck side.

You should also learn whether your blades spin clockwise or anticlockwise when mowing. This detail will be handy when uninstalling and reinstalling the mower blades.

2. Check the blade for etchings, signs, or stickers

Manufacturers sometimes make it easier for you to identify the orientation of your cutting blades by etching the required information on the metal.

Others may also use marks or stickers with the information instead. So you can expect to see wordings like “Grass Side,” “Toward Grass,” or “This Side Down,” indicating the side of the blade to face the ground.

If this information is cut into the metal, it will likely be permanent. However, if the manufacturer uses stickers, they may fade or wear away as the blade gets older.

But it helps to check first anyway. If you are out of luck with these writings, consider the other methods below.

3. Look for the sharp end

The sharp end is the blade’s cutting edge. This should be easy to identify since it will be sharper than the opposite end, which should be noticeably blunt.

Each blade has two cutting edges, each on the opposite ends from the center hole where the blade connects to the spindle.

Since the blade rotates in one direction, either clockwise or counterclockwise, these two cutting edges face that same direction.

Once you identify this sharp edge, you will notice that it is closer to the ground than the edge behind it, which will be noticeably dull and bent upward (toward the deck).

That dull, trailing edge is the side to face up when reinstalling a lawnmower blade.

4. Check for wobbling in the blade after installation

If you install the blade and are unsure whether the right side is facing up, you can check if the newly installed blade feels wobbly.

A blade installed correctly should be firm once you have tightened the bolt attaching it to the spindle.

So if it feels unstable, you may have placed it upside down—time to correct the orientation.

Why Does it Matter Which Side of Your Lawn Mower Blade is Up?

The correct positioning of the blade can affect both the lawn and the mower itself, which explains why the orientation of the blade is crucial.

Positioning the blade with the right side facing up helps ensure proper airflow under the mowing deck.

This flow of air while the blade rotates contributes to an even cut by appropriately directing the clippings.

This section breaks down these reasons to help explain why the extra effort to ensure the correct cutting blade orientation is worth it.

1. The wrong blade orientation will damage your lawn

Since the lawnmower blade is designed to cut in one direction, flipping it upside down when installing it means the cutting edge will never cut grass.

The sharp edge will spin away from the grass, while the dull edge faces the lawn when mowing.

The force from the fast-spinning blade will still generate enough power to remove the grass. However, it will shred the grass instead of cutting it neatly.

Much of your shredded lawn will become brown as the torn grass dies away. Your lawn may take a while to recover from such damage.

2. You may end up with a damaged mower

When the wrong side of the blade faces up, it may remain unsteady. Such an unstable blade will likely wobble while rotating, and this could mean the metal is nicking the underside of the deck, damaging it in the process.

The wobbly blade can also affect the spindle and the nut bolting it to the spindle.

Additionally, the blunt side may hang too low when upside down, nicking the ground, or hitting rocks when you mow over uneven surfaces. This can leave dents around your yard or lawn after mowing.

3. The wrong blade orientation will create an uneven cut

Because the blade’s dull side simply hits the lawn instead of cutting it clean, some grass will remain taller than others, creating an uneven look.

The dull edge will also be unlikely to cut harder grass the same way as the softer ones. This will further contribute to the unevenness of your cut.

In some areas, the blunt edge of the blade may pull some grass from the soil, exposing the roots.

4. You may damage your blades

While wobbling, hitting rocks on the ground, or nicking the underside of the mower’s deck, the blade may get dented in various parts or bent depending on the terrain and how long you use it improperly.

At worst, it may get caught up on some objects and get broken or break your mower’s spindle.

So, when removing the cutting blades from your lawnmower, always take your time to observe its orientation to get it right when installing a new one or replacing the existing blade after you have sharpened it.

See: Do mower blades come sharpened?

What Happens if You Install Your Lawn Mower Blade Upside Down?

If you install the blades on your lawnmower upside down, the sharp edge intended to cut the lawn will be facing away from the grass when mowing.

As a result, you will hit the grass with the dull end, damaging your lawn. This blunder can damage both your lawnmower and the lawn, making it potentially costly and dangerous.

Different Types of Lawn Mower Blades and their install direction

Which Side of the Lawn Mower Blade is Up Image

Not all blades are created equal. There are different types of lawn mower’s blades are available, and understanding the differences and correct uses may help you make the most of each.

Knowing the various types of lawnmower blades is especially helpful because some can accept different blades.

Some blades can also perform more than one function. For instance, a mulching blade can also be used for bagging.

Also, the knowledge about these differences should come in handy when buying replacements for your worn blade sets.

You want to ensure the piece you are purchasing is compatible with your mowing unit.

Standard cutting blades

Also referred to as straight or medium-lift blades, they are typically found on lawn mowers with  a side discharge chute that discharge their grass clipping on the side.

These blades feature a small curvature on each end. This design helps with discharging the debris by creating an uninterrupted airflow as the blade rotates.

The small curvature at the end of the blade creates a suction force as the blade spins, leading to a clean cut and the pressure needed to direct the clippings to the discharge location.

These standard blades are most efficient for cutting grass in areas with large patches of grass.

Standard blades are also referred to as baggers because they effortlessly send grass clippings into the bag for lawn mowers with a bag attachment. This is due to the suction force the blades create.

The high lift cutting blades

These lawnmower blades have a distinctive edge design featuring a prominent upward curve.

The edges of a high-lift mower blade are angled vertically, allowing for maximum suction force and airflow through the blade shaft. 

High lift cutting blades are associated with cleaner cuts as the grass remains straight while awaiting trimming.

The powerful suction force makes these blades perfect for bagging. This explains why they are the most popular blades among lawnmowers with bag attachments.

Low-lift cutting blades

As the name suggests, low-lift blades have low suction capacity due to their less curly edges.

They are best used on lawnmowers discharging their grass on the side (side discharge mowers) as they cannot throw the grass too high.

Thanks to the low suction, the blade design makes it ideal for mowing in sandy areas where they won’t throw the sand around.

Mulching blades

Mulching blades are called 3-in-1 or multi-purpose blades because they cut grass and shred it into pieces (mulch). These pieces then return to the lawn as organic fertilizer.

Mulching blades have a curved surface with teeth and a unique design that allows it to raise the grass toward the deck and cut it precisely before shredding it into fine pieces.

These blades are used on a mulching lawnmower that discharge grass clipping by expelling them to the soil as fertilizer.

These are the best lawn mower mulching blades if you want to avoid dealing with debris after mowing. The blades leave nothing to collect after mowing

Gator butting blades

These blades resemble mulching blades, except they generate more suction force than mulching blades.

As such, consider them a more efficient version of mulching blades, accomplishing the work more effectively.

Mulching blades are typically found on mulching mowers and have more prominent teeth capable of shredding taller grass more easily into mulch.

See: Best blades for zero turn


Which way do mulching blades go on?

Mulching blades should be installed with the curved edge facing upwards toward the mower deck.

This enables a cutting and lifting action, effectively mulching grass into smaller clippings for distribution back onto the lawn. Always consult the mower’s manual for proper installation instructions.

Can you put the mower blades on upside down?

Yes, you can put most lawn mower blades upside down because the metal typically features a cutting edge at each end. However, this accident can lead to serious damage to the lawn and even the mower itself, so you should always be keen to avoid installing the blades upside down.

Can I sharpen my blades instead of changing them?

Yes, you can sharpen your mower’s cutting blades and reuse them for as long as possible before requiring a new set. Lawnmower blade replacement only becomes necessary when the current blades are damaged or bent. Here’s the best grit for sharpening lawn mower blades to help you get started.

Which side of the mower blade faces down?

The flat side of the mower blade faces down, while the curved or sharpened edge faces upwards towards the mower deck.

This orientation allows the blade to properly cut the grass as it rotates, ensuring an efficient and effective mowing process. Always follow the manufacturer’s guidelines for safe and proper installation.

How do I know which size lawn mower blade I need?

Replacement blades are typically labeled to indicate the mower deck size they correspond to.

You can know the size of the lawnmower blade you need by checking the label against the size of your deck. For instance, a 42-inch deck will require blades labeled 42 inches.

How should mower blades be positioned?

Mower blades should be positioned with the flat side facing down and the curved or sharpened edge facing upwards towards the mower deck.

The orientation allows the blades to efficiently cut the grass as they rotate, ensuring a well-maintained lawn.

Follow the manufacturer’s instructions for correct blade positioning to ensure safety and optimal performance.

Also, learn about blade positioning on a 3-blade mower deck for a comprehensive understanding.

Final verdict – Which Side of the Lawn Mower Blade is Up?

It helps to err on the side of caution when deciding which side of the lawn mower blade is up.

Take your time to study the blade before you start untightening it to remove it. Specifically, identify the cutting edge and note which direction it faces.

Once you have this information, you can tell that the dull edge will be facing up. This should simplify your work when installing the replacement or reinstalling the current set.

If the blade set has marks or stickers indicating the blade orientation, your work will be simplified.

Otherwise, the guidelines in this article should help you determine the correct lawn mower blade position.

If you have any thoughts or addition, let us know in the comments.