Why is My Mower Cutting Uneven Lines? How to Fix It

Many homeowners attempt to master the art of cutting perfect lines in the yard, but only a small percentage are successful. If the lines that your lawn mower cuts are always uneven, then you have arrived at the correct location. There are many factors that can contribute to how your grass looks, as well as a variety of ways to improve its appearance. When the deck, wheels, or blades of a mower are not leveled, it produces lines that are not even. You can verify the distance between the deck and the ground by using a measuring tape if you want to be absolutely certain. Choppy lawn cuts can also be caused by wet grass, loose parts, and uneven weight distribution when mowing the lawn.

Here’s Why Your Mower Lines Look Bad

After the lawn has been mowed, uneven lines will appear as wavy or choppy patches. Once you know where to seek for the answer, determining what caused the unstable mowing is not difficult. The following is a list of general principles regarding the possible causes of uneven lines: Always refer to the user manual whenever you need more detailed information regarding the brand of lawn mower you own.

Loose or Tilted Deck


The deck of a lawnmower is the section of the machine that contains the blade. During the mowing process, irregular lines may be produced if the deck is loose or inclined. The deck may deteriorate with age or bend as a result of regular wear, and tilting may occasionally occur as a result of a manufacturing error. Because the cutting deck and blade of some mowers are linked, an uneven cut may result from a tilted cutting deck.

To determine whether or not this is the case, you should first park your mower on a level, flat surface such as a driveway, and then, utilizing a tape measure, examine the height of the deck relative to the level surface on both the left and right sides of the mower. The two measurements need to be identical to one another.

If there is a variation in height of at least one quarter of an inch, the deck will need to be adjusted. When grass clippings fill the deck, it reveals that the trimming was not done evenly.

After you have finished mowing, you should always make sure that the deck is cleaned out. If you want to avoid damaging the deck, removing huge weeds with a mower is not a good idea; instead, make sure you follow these instructions.


Tilted or Blunt Blades


The cutting blade of the majority of lawnmowers is rotated by a shaft that is driven by a belt. There are instances in which the blades of this mower are fastened directly to the motor. A misaligned or bent shaft is the cause of a one that is inclined. Manually rotating the wheel until each end is directly facing to the left or right of the mower is one way to determine whether or not the blade is slanted.

Use a tape measure to determine the distance that separates the tips of the blades from the level surface. The misalignment is evidenced by a variation in height between the blades, and this is the root cause of the uneven lines. It is important to keep the blades on your mower sharp since uneven cutting can result from dull or worn blades.


It Might Be the Wheels


When using riding mowers, uneven mowing occurs because the wheels experience uneven pressure, which causes the mower to lean to one side. If you observe an appearance on the cut grass that looks like slanted stair steps, you need to make sure that the tires on your mower are inflated to the recommended specification. This is according to Jack's Small Engines.

If you are unable to inflate them, you may need to purchase a new pair (dull plastic or rubber causes unevenness). Lawnmowers that require the user to walk behind the machine include wheels that assist in adjusting the cutting height. One of the wheels may have been adjusted differently than the others, which resulted in an uneven cut of the grass. It is important to remember to grease the wheels of the mower as well.

Slow the Engine Speed


Your lawn will have uneven lines if you mow it at a speed that is insufficient. If you move the mower over the yard at a slower frequency, you will end up with stripes that are not even. If the engine speed is low, the blades will spin slowly, which will result in an uneven cut over your yard. On the other side, if you move too quickly, you can end up making sloppy cuts.


Uneven Weight Distribution


The most common cause of uneven cuts in riding lawnmowers is incorrect weight distribution. If the weight distribution is unchecked, then your mower is likely to mow unevenly.

Mowing Wet Lawns isn’t Always Ideal

Mowing on a wet lawn is ill-advised since the grass blades are tough to slice through when wet. The rows of cut grass lead to uneven trim. The grass also tends to stick on the mower blades making it hard to mow. You’ll notice that it looks chunky and unsightly.

How to Fix a Lawn Mower’s Cutting Pattern

Leveling the mower deck side to side involves the following steps:

Note: To level your mower deck, you will require a ruler or tape measure, a wrench set, tire pressure gauge, compressed air supply, and work gloves.

  1. Park on a flat level surface, set the parking brake, then inflate all the tires evenly.

  2. Elevate the deck to its highest position and disengage the cutting blades.

  3. Shut off the engine and detach the ignition key.

  4. Inflate all the tires evenly to their recommended pressure. 

  5. Position the side of the cutting blades to have it level. Measure the height of each blade tip. The difference should not be more than 1/4-inch.

  6. Turn the lift link adjustment nut clockwise to raise the left side of the deck or counterclockwise to lower it if the height difference is significant.

  7. Continue adjusting the lift link until the height measurements are equal.

Adjusting Front to Back

  1. Adjust the deck from front to back by placing a cutting blade from back to front. Measure the height of each blade tip. The front blade tip should measure 1/8-inch to 1/2-inch lower than that of the back-blade.

  2. Adjust and raise the front of the mower deck by turning the front link adjustment nut clockwise. To lower it, turn counterclockwise.

  3. Check the blade height measurements after adjustment and compare. Continue to adjust the front link adjustment nut until the front blade tip is 1/8 inch to ½ inch lower than that of the back-blade.

  4. Use one wrench to hold the adjustment nut and tighten the jam nut with a second wrench.

If you want a quick video tutorial, follow the guide by SearsParts Direct:

Mowing Perfect Lines with Any Lawn Mower


It is not difficult to achieve those perfectly aligned lines on your lawn. The grass blades need to be flattened in opposite directions in order to reflect light in a variety of various ways. It creates the idea of stripes when viewed from above.

In order to accomplish this, you will need a back mower that is specifically designed to press the grass blades down in the direction that the mower is moving. The lawn is given a striped appearance because, in addition to cutting the grass, the roller of the mower presses the grass down as it moves across the lawn.

If you don't have a mower like this one, you can rent a second roller to use after you mow your yard so that it is more even. As an alternative to renting a roller, you might make your own equipment for leveling the grass and attach it to the rear of your mower instead.

Make sure that the initial cut line is exactly straight as this is the first step in attaining those perfectly straight lines. In order to accomplish this, you should walk along something that can act as a guide, such as a driveway or a patio, or you might use two stakes and a thread instead.

When you reach the end of the first line, lift the mower's blades so that they may be spun around, and then move into position. Continue doing this throughout the rest of the lawn while focusing on maintaining your balance. Check out this article by SF Gate for more instructions on how to do it.

When you are prepared to take your mowing of the lawn to the next level, read the article on mowing that is located in the Lawn Care Lessons section to learn how to get perfectly straight lines.




It's possible that repairing the cutting lines on your lawn mower will take a few hours of your time, but the results will be well worth it. You are going to be quite pleased with the end results, and once you are aware of any potential pitfalls, maintaining them won't be difficult at all.

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