Here’s How to Tell Which Side of the Lawn Mower Blade is Up

Approx Reading Time: 7 minutes

When it comes to yard maintenance and landscaping, few tools are as useful as a functional lawnmower. But for your mower to perform at its best, the blade needs to be set correctly. Using the blade on the right side is crucial for the best performance and ultimate longevity in your lawnmower.

To determine which side of the lawnmower blade is up, identify which side of the blade is dull, and which is sharpened. The sharpened edge, or cutting edge, is sharpened to a point and should face the ground and will have a taper facing the sky. The dull edge is bent and should face the mower deck. 

Read on to learn how to tell if your mower blade is installed correctly, a few tips for making it easier to tell in the future, and what could happen if you put the blade in the wrong way. 

How to Tell Your Lawn Mower Blade Is Up

There are a few telltale signs that indicate whether or not your lawnmower blade is “up,” or on the right side. Thankfully, these signals are simple and straightforward to identify on most models of recreational lawnmowers.

As a precaution, ensure the utmost safety standards are upheld before performing maintenance on your grass-eating machine.

Find “This Side Down” or “Cut Grass” Stamp

Contrary to the well-intended advice of amateurs, lawnmower blades are not interchangeable and cannot be flipped. The majority of lawn mower blades will contain a sticker or stamp indicating which side the instrument should be facing.

Some models will have words engraved or machine-printed onto the blade; over time, rust may cover these seals.

If your mower blade does not have a sticker, you can buy or make your own sticker so you don’t forget which side should face up. If you choose to do this, be mindful of where you place the sticker, so it doesn’t interfere with any other parts.

Locate the Cutting Edge on the Blade

The most reliable and effective way to tell your mower blade is up is to recognize the cutting edge of the instrument. This edge will be clearly sharpened, especially compared to the duller side. The cutting edge should face the grass, as it will be chopping the grass.

Additionally, there should be tapers on the ends on the blade. These should point to the sky, if the blade is in the right spot.

As a friendly reminder, always practice caution when handling a mower blade. A chopped finger or another injury can be prevented by unplugging any connected wires and removing spark plugs before performing at-home maintenance on your mower. Mowers can be replaced, but fingers (or worse, lives) cannot.

Cutting edges are not always interchangeable. In fact, unless the center hole and the length of the instrument are the same dimensions as the original one(s), they should not be used in a lawnmower. Using the wrong blade on a mower could lead to a whole new slew of performance issues.

The edges of the mower blade often get worn out over time, becoming dull and leading to a reduction in cutting capability. To avoid a choppy lawn, be sure to keep your blades sharpened.

Perform the “Wobble Test”

Once blades have been adjusted or replaced, the final step to make sure they are secure in the mower is to put them through the wobble test.

This easy stress test will tell you whether or not your blade is liable to fall out while you mow, and if it is going to mow effectively. 

To clarify: if there is a wobble, that means there is an issue. Here is the list of steps to follow when performing a wobble test:

  • Hold the mower blade with one hand, and the deck (the part that acts as a sort of shield and protects you from the open blade) with the other hand.
  • Give the blade a tug, and pull it down gently.
  • The blade should not wobble if it is on the right side, with the sharp edge facing the ground. If it does wobble, ensure it is on the blade shaft. Tightening the securing bolt with a wrench can help you to do this.

Once the wobble test has been completed, your lawnmower blade will be secure and ready to go. Tip your mower back onto its wheels, and you are all set.

Differences in Other Lawnmowers

In lawnmowers other than the standard rotary push ones, there are variations in the ways to find out which side of the blade is up. Mulching and reel lawnmowers may not have any clear indication, which could lead to mistakes when performing maintenance or replacing your mower blade. 

Mulching Lawnmower

The identifying feature of mulching lawnmowers is their ability to collect the grass clippings leftover once the grass has been cut. Clippings are great for compost or just to rake into your lawn for an easy natural fertilizer. This makes mulching mowers especially useful.

Because it serves a slightly different purpose, that means mulching mowers use a different blade. Mulching blades tend to have a model number or stamp on the bottom side of the blade, which should face the ground. 

If there is no clear indication of which side is down, look at the sides of the blade. There will be more curves on a mulching blade, and the cutting edge will not be as clear to identify as the one in a standard mower. 

There should be curves on the cutting sides of the blades, and the pointy parts on the end should face upward toward the lawnmower body. Once you’ve located your cutting side, feel free to mark it with a sticker, like we talked about before.

Reel Lawnmower

Due to their cylindrical nature, reel lawnmowers do not really have an “up” side or a “down” side. They pretty much just roll like a wheel. If you have any doubts about your reel lawnmower blade, take a look at a manual or contact a local application store. 

What Happens If You Put Your Blade the Wrong Way

Putting your lawn mower blade on the wrong way will damage not only your mower but also your lawn. Blades are built to be used on a particular side and placing it on the wrong side often results in internal damage to the mower.

This means that the blade, the mower, or both are more likely to need replacement.

Fortunately, when it comes to lawnmowers, simply flipping a blade over can save it from any severe damage. 

Damage to Grass or Surface

Functional mowers leave lawns looking clean and even, much like a fresh haircut. With the blade on backward, there is no sharp edge cutting the grass, and the grass is cut unevenly. Unless you enjoy choppy, messy grass, placing the mower blade on the right side is a must. 

Repeatedly mowing with the blade on upside down could result in the uprooting of grass or low-lying growths, creating spots devoid of growth (if your mower isn’t destroyed first). Like using an incredibly dull mower blade, using the wrong side of a blade will not give a clean cut.

Damage to the Lawn Mower 

As you can imagine, having a part of a functioning machine facing the opposite direction it was meant to face can lead to issues within the system. In this case, damage can present itself in several ways. Although the effects differ between the brand and length of time that a blade is misused, here is a list of consequences that are liable to happen:

  • Poor grass cutting
  • Structural damage to the undercarriage of the mower
  • Damage to the blade
  • Reduction in overall lawnmower effectiveness 

Before testing out which side of your blade is up, take a look at a manual or inspect the blade itself. 

Above all, remember: a beautiful lawn doesn’t happen by itself.

Peter Toth

Hi! I'm Peter, the owner of BackyardGadget. Working around the house has always been a big part of my life. I've created this site to share my experience, and to help people choose the right tools for the job. Thank you for stopping by!