Which side of the mower blade is up can be tricky for those who have only recently bought a lawn mower. Both sides of the mower blade have different purposes in grass cutting, and we understand that it might be confusing for new mower owners to differentiate between the two sides.

Which Side of the Lawn Mower Blade Is Up

You cannot interchange both sides because this can damage the grass and the mower, sometimes even beyond repair.

In this complete guide, you will discover which side is up, along with several methods to determine this side practically. 

What Side of Your Lawn Mower Blade Is Up?

The side of your lawn mower blade that is up is the one with slightly raised edges. This side faces the lawn mower deck and has a dull cutting edge compared to the other side, which has a sharper cutting edge.

Here are some fool-proof ways to figure out which side of the lawn mower blade is actually up.

– Clearly Written on the Blade

Even the manufacturers understand that it gets confusing to tell both sides of the lawnmower blade apart. To make things easy for us, most of them put clear stamps to indicate which side is which on either side of the blade. The cutting side will be the “grass side” or the “downside,” while the other side will usually be the “upside.”

A sticker will be attached on both sides, if not a stamp. However, most of us lose this important sticker from our mowers with frequent use and washing. We like it best when proper engravings indicate both sides of the blade. Engravings make things so much easier and do not fade over time. 

You can buy your stickers and stick them on the right side. Double-check that you are sticking these stickers on the right side first. If you have a laser engraving device, that would be even better than stickers. 

– Doing the Wobble Test

It is okay if your lawn mower did not come with engravings or stickers marking the sides of the cutting blade. You can always tell which side of the blade is up using the wobble test method. This method always yields accurate results and is very easy to perform. 

  1. First, you want to turn the mower off before doing anything with the mower blade. We even turn the spark plug off so that there isn’t any risk of the mower starting accidentally, either.
  2. Tilt the mower over on one side so that you can gain easy access to the blade. The mower needs to be balanced while tilted; otherwise, it will end up falling on you.Doing the Wobble Test
  3. Hold the lawn mower blade in one hand and the deck with the other hand. 
  4. Tug and gently pull the mower blade downward and notice whether or not it wobbles. 
  5. The blade will never wobble unless it has been attached the wrong way. Check that the bolt securing the blade with the mower is tight because this can also cause wobbling.
  6. If the wobble test indicates that the blade was attached incorrectly, remove it and reattach it on the opposite side. Perform the test again, and you will see how the wobble will have disappeared this time around. 

– The Wing Side Faces Up

The side of the lawn mower blade that faces up has a blunted and dull cutting edge. The blunt edges have very slightly raised edges that look like tiny wings. They have been specially designed to produce an air vacuum and lift the grass blades. Once the air pressure lifts the grass blades in a vertical position, the blade’s cutting edge smoothly chops them down.

Sometimes, the raised wings on the edges of the upper side are more challenging to see visually. You will feel these wings rise if you run your finger along the edge. Using your tactile sensation, you can easily gauge which side of the blade is up and which is down.

– The Non-cutting Side of the Blade Is Up

Once you identify the cutting edge of lawnmower blades, you will never again confuse its two sides with one another.

The cutting edge is the one that should always face the ground because it is going to cut grass. Unless your blade is really old, the side with the cutting edge will be visibly sharper and shinier than the other side, which will have a dull and blunt edge.

The side of the blade with the blunt edge should always face upwards towards the lawn mower’s deck. If you need clarification on both edges after a simple visual inspection, use a piece of paper to see which edge cuts through it more smoothly. 


– Rotate the Blade

Do you want a quick test to see whether you have fitted the mower blade correctly? Once you have finally installed the blade, keep the mower tilted to the side and rotate the blade in the mower. If the lawn mower has been tilted on the right side, move the blade in the counterclockwise direction. 

If the blade has been installed correctly, the lower side with the sharp edge will be the leading edge. Otherwise, you must remove the blade and turn it upside down correctly. 

– Mulching Blade’s Top Side

Mulching blades are different from regular mower blades because they cut grass and convert it into mulch . These mulched pieces can then be used to make compost, mulch, or rake for the benefit of your lawn. You can tell a mulched blade from a regular one just by looking at it, as it is more curved.

Most standard mulching blades have a serial and model number engraved onto them on the bottom. The smoother side will naturally be the upper side. These engraved numbers and wordings are easily visible under bright light, and this side should always be towards the grass.

Mulching Blade’s Top Side

The second way to tell which side of the mulching lawn mower blades should face up is by determining its cutting edge.

The cutting edge of the mulching blade is more easily identifiable than that of a regular blade. The blade’s non-cutting or the upper side will have slightly-raised edges or tiny flaps that bend upwards. You need to ensure that this side always faces the mower deck. 

Lastly, look at which side of the blade has a beveled cutting edge. It is easier to notice this bevel under sunlight or light from a torch. This is most definitely the upper side of the mulching lawnmower blade. 

– Reel Lawn Mower’s Up Side

The reel type of push mower is an exception because its cutting blades have no ups or downsides. The mowing blade of these mowers is arranged in a cylindrical manner and rolls like a wheel while cutting grass.

Be Careful Not to Drown the Pepper Plant

Since the edges of the blade are equally sharp, it doesn’t matter which side is up or down in a reel mower.  

Why Is It Important To Attach Mower Blade Right Side Up?

It is important to attach mower blade right side up or the wings side up because this is what keeps the mower working properly. Otherwise, the mower and the cut grass end up incurring damages, and the grass will not be cut evenly.

– Prevent Damage to the Mower

You can imagine how a machine will react when its parts are not attached correctly. The grass-cutting property of the mower will be impaired negatively, and the inner working parts might get damaged too.

Prevent Damage to the Mower

It also matters how long you have been misusing the mower blade. The longer the blade is used upside down, the more damage you can expect the mower to incur. The mower’s undercarriage, including the deck area, is particularly prone to damage. The engine gets strained as you push it harder to cut the grass. 

– Prevent Damage to the Grass

When you accidentally install the blade upside down in a mower, the dull cutting edge has to do the work of cutting the grass. This edge was designed for something else and will do a terrible job overall. When the grass blades are cut using a dull blade, they get damaged.

Observe closely and you will notice that the grass seems crushed at its growing edges instead of being trimmed smoothly. A grass cut from the top side of the mower will grow back slowly and healthily. Your lawn will also not achieve the refined, clean look one expects after a grass-mowing session. It will look untidy and choppy, with patches of grass cut unevenly.

If you carry on cutting grass using the wrong blade side, your grass might eventually stop growing, and the lawn might develop bald patches.

– Top Side Cuts Grass Unevenly

Both sides of the blade have their purpose while cutting grass and must be installed correctly. When the blade gets attached upside down, the upside creates no air vacuum. The grass blades will only be forced to stand upright with a vacuum. 

Top Side Cuts Grass Unevenly

The result will be that the grass will be cut at varying heights throughout the lawn. This is the worst nightmare scenario for any lawn care enthusiast. A grass cut unevenly will also grow unevenly and make the lawn look like one huge mess. 

– Blade Gets Bent

Mower blades installed wrongly upside down get damaged and broken easily, especially if you have been neglectful and have been using the mower this way for a long time. Remember those raised wings that are present on the upwards-facing side? These wings are supposed to face the mower deck and remain untouched as the blade rotates. 

When one uses the blade upside down, these wings are constantly getting hit by the ground, grass blades, rocks, and other stuff.

Eventually, cracks develop and spread from these wings, or the blade gets bent. Once a lawn mower blade becomes damaged, it rarely gets fixed. You must let go of it and buy a new one instead. 

– The Crankshaft Might Break

The crankshaft of the rotating mower blade is also at risk from blades installed improperly. The upside has raised edges and wings that frequently bump with stuff present on the ground. All the extra pressure generated is then transferred to the crankshaft. 

The Crankshaft Might Break

If the blade gets cracked or bent, the shaft is also at risk of getting bent. In the worst-case scenario, you might have a broken crankshaft altogether.

This will lead to a much more extensive repair from a professional. All this effort and money could have been spared if only the blade had been attached with the right side up. 

Frequently Asked Questions

– Is the Right Placement of Lawn Mower Blades Side Important?

Yes, the right placement of lawn mower blades side is important for cutting grass smoothly and working the mower. Otherwise, your grass will be cut in a choppy, rough, or uneven manner. In some instances, doing this might even damage your mower beyond repair.

This is because the top side of the blade has a blunt cutting edge and has not been built to cut grass. Instead, its job is to lift grass blades via an air vacuum so that the cutting edge of the lower blade can cut it.

– Are There Left and Right Blades for Lawn Mowers?

Yes, there are left and right blades for lawn mowers. This means that the blade’s cutting edge is either present on the right side of the blade or the left side. Consequently, a left-sided blade is not interchangeable with a right-sided blade.

When changing your old blade for a newer one, check which type of blade works with your lawn mower so that you buy the right one. A wrong side blade should not even be installed onto your mower. 


This is the end of our exhaustive guide on which side of the mower blade is the upper side, and here are the key take-away points.

  • The side with tiny raised wings and edges on it is the side that should be facing up towards the mower deck.
  • The cutting edge of this upside is dull and blunt, while the cutting edge of the downward-facing side is sharper.
  • If the lawn mower blade has been attached incorrectly, you can test it using the wobble method. An improperly attached blade is not going to stay still and will instead wobble.
  • Fortunately, most companies either engrave the name of the sides on their blades or attach stickers.
  • If your mower has no engravings, you can always post stickers to prevent future inconveniences.

Learning to identify both sides of the mower blade is very important because these are different from one another. Once you accidentally attach the mower blade the wrong way and keep using it like that, it could seriously damage the mower and the grass.

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