how loud is a robot lawn mower

Are Robot Lawn Mowers Loud?

Robot Lawn Mowers work best when they are set to cut your grass multiple times per week, and often for several hours each day. Conventional lawn mowers are very loud and disturb the peace of your garden. When people start to think about this, they usually ask the question – Are robot lawn mowers loud?

The short answer is that robot lawn mowers are very quiet, and wont disturb the peace of your garden even when they are working in close proximity to you while you relax in your garden. The noise output varies from from model to model, but most robot lawn mowers range from being almost silent, to about the same volume as two people holding a conversation. 

Everyone knows how loud conventional lawn mowers are. When I’m out enjoying my garden on a sunny afternoon, the last thing anyone wants to hear is the sound of a lawn mower blaring away. When I used to have a conventional lawn mower, my wife used to get really irritated by the noise of it in action.

My small kids used to really hate it too.  My lawn mower was so loud, that I couldn’t even use it while my two year old daughter was having her nap in the afternoon, as she would wake up crying if I did. This was quite restrictive, and meant that I had to time my lawn mowing activities to certain times.

When I’m out doing some gardening, or relaxing on the patio, the last thing I want to hear is the sound of a neighbour cutting their grass. It really destroys the peace of the garden and means I’d rather sit inside until the noise stops. 

Since making the switch to a robot lawn mower, I no longer have to worry about the noise. My robot lawn mower works quietly in the background for several hours each day.

Even when I’m sitting on the patio or enjoying another part of the garden, most of the time I can’t even hear the robot lawn mower in action. Sometimes when it comes to within about 10 feet of me, I can hear a gentle whirring noise, but it certainly isn’t distracting or annoying.

Are Some Robot Lawn Mowers Quieter Than Others?

There is some variation in the noise output of robot lawn mowers. Even so, they are all considerably quieter than a conventional lawnmower. The range in noise output from the quietest robot lawn mower to the loudest is from 58 to 74 decibels. This is roughly equal to the difference between quiet conversation and a vacuum cleaner in operation. In contrast, conventional lawnmowers produce an average of 90 decibels of noise. Bear in mind, that each increase of 10 decibels, equates to a doubling in the perceived noise of a sound. This means that the quietest robot lawn mowers sound approximately eight times quieter than an average conventional lawn mower.

The variation in noise output of robot lawn mowers is less to do with the size of the robot lawn mower, and more to do with the cutting technology that is used in that specific machine. There are two main cutting mechanisms used in robot lawn mowers.

Models from Bosch, Husqvarna and Flymo for example, use small razor blades attached to a spinning disc. The blades rotate freely on their mountings. Due to their small size and low energy, they are very quiet in operation.

If you are looking for a near silent robot lawn mower, I would strongly recommend that you opt for one of these models. This will enable you to have a robot lawn mower which you can barely hear even when it is working away in your garden and you are in close proximity. It is this type of model which I use personally, and I would recommend this type to most people.

cutting blades on spinning disc my robot lawn mower

The second cutting mechanism used in robot lawn mowers is the fixed blade system. These blades are individually mounted under the robot lawn mower and can be either alone or in groups, depending on the size of the robot lawn mower. This is the cutting mechanism used by Robomow models for example. These fixed blades have a higher energy and increased cutting power and therefore make more noise in operation. There are some benefits to having fixed blades, which offset the increased noise output.

The blades are more durable and need changed less frequently. Models with this cutting system typically have a wider cutting diameter, and are often able to cut closer to the edge of your lawn, leaving a smaller strip of uncut grass.

robomow robot mower showing blades

If I Can’t Hear The Lawn Mower, Is There A Chance Of Injury If I Don’t Pay Attention?

The good news is that the risk of injury from a robot lawnmower is incredibly small. Even if a robot lawn mower was completely silent, the safety features would ensure that no injury is sustained if it were to bump into you inadvertently.

It is very common for people to raise concerns about the safety of autonomous robot mowers, mainly due to their use of sharp spinning cutting blades. Thankfully, safety has been at the forefront of the development of robot lawn mowers for precisely this reason. The safety of robot lawn mowers has been shown to be near perfect, compared to the very poor safety record of conventional lawn mowers. Read more about the safety of robot lawn mowers in this article.

Robot lawn mowers have cutting blades which are tucked well under the body of the robot. Lift and tilt sensors prevent access to the blades without the emergency stop being triggered, which stops the blades in a fraction of a second. Collision sensors mean that when a robot meets an obstruction, it simply backs up and goes in a different direction.

I am more than happy to let my robot lawn mower continue to operate while I am enjoying the garden. Even if I had a hearing impairment, I could rely on the mower to stop when it came into contact with me, without causing any injury.

The Sound Can Help You Know When To Clean Or Change The Blades

I have noticed an interesting point about the noise that my robot lawn mower makes. After I install new blades and clean the underside of the robot lawn mower, the sound that the mower makes will be slightly different than when the blades need changed or when the underside of the mower needs cleaned.  

Generally it starts to make a slightly different and louder noise as the blades become less sharp. This results in the blades of grass being cut less cleanly, which requires more cutting force. The sound also changes when there is a build up of grass debris around the cutting system, causing interference to the movement of the blades. This is quite subtle, and I only really turned into this change in the sound after a few months of using my robot lawn mower.

The good news is that this lets me know when I should clean the underside of the robot lawn mower and when I need to change the blades. I normally give the underside of my robot lawn mower a clean with a stiff brush approximately once per month and change the blades every 3 months. I think this change in sound from the robot lawn mower is something that will only be noticed from robot lawn mowers using freely mounted blades on a spinning disc, such as models from Bosch, Husqvarna, and Flymo.

What About The Noise From My Neighbour’s Lawn Mower

Getting a robot lawn mower will leave you with a machine that will cut your grass very quietly and reliably. Unfortunately it won’t do much for the sound of your neighbour’s lawn mower. I would have to admit that there are still times that I’m trying to enjoy my garden, and I hear my neighbour’s lawn mower blaring away.

The good thing about this is that it reminds me how much effort it used to take for me to cut my lawn. I’m now able to spend the extra free time enjoying other activities such as relaxing in the garden. Hopefully, as the adoption of robot lawn mowers increases, I may hear the sound of a conventional lawn mower less and less frequently in the future.