Robot Window Cleaners – Are The Right For You?


I don’t do windows – but I know some”bot” who does.  Sorry for the bad pun…  As I was researching spring cleaning topics, I came across an item that I honestly wasn’t aware of, Robot Window Cleaners.  Maybe not like the picture above, but these little gadgets are pretty cool and could be a nice addition to your cleaning arsenal and potentially save you money. Everyone hates cleaning windows, especially the outside of windows that are on upper floors.  Not only is it difficult, it, could be dangerous if you plan on using a ladder to get to them.


So, we either don’t clean them, hire an expensive service, or look for one of those cleaning solutions that attach to the end of a hose and hope shooting a sudsy stream of water 30-40 feet in the air works.   

If you hire someone, you could pay as much as $10 – $15 per window, so add up the number of windows and you can come up with an estimate of what it might cost.




It’s important to evaluate your situation to make sure that spending several hundred dollars on a robot window cleaner makes sense.  What you don’t want is an expensive toy that doesn’t really save you any time or effort and it’s easy enough to use that you will actually use it.



Mullions: Cleaning robots use suction from a vacuum pump to adhere to a window, so they must have continuous contact with the surface.  Exterior mullions, (the horizontal and vertical bars on your windows) either decorative or real in the case of older windows, will be a problem for a robot.  In some cases, decorative mullions are removable, so you will have to decide if you want to go through the effort of removing, then replacing them after the cleaning is complete.  That would not be my choice.  

In most cases, windows today have decorative mullions that are placed between the double panes of the glass, so these would not be a problem for a cleaning robot. 


Inward Tilting Windows: Most windows will tilt in these days, which makes cleaning the outside easier, but it’s still a chore that I hate, but it is doable, and it makes attaching the robot easy. 


If you have windows that don’t have inward tilting capabilities and have to get to them from the outside or reach up from inside to clean the outside of the upper pane, then a cleaning robot may be helpful.


Contemporary Design:  If you have a modern contemporary designed house with a lot of glass like the one below, you are either paying someone to clean all the glass or you are using a lot of Windex and extension ladders.  In cases like this, a high end robot is almost a necessity.



Most robotic vacuum cleaners are held vertically in place with suction from a vacuum pump.  A small number use magnets on the opposite side of the glass, however, since vacuum is by far the most prevalent method, we will focus our attention there.   

Vacuum, or suction is measured in terms of Force (F) per unit Area (A), the most common term people are familiar with is PSI or Pounds per Square inch.  This is easily understood as everyone knows what a Pound is and what a square inch is.  However, vacuum suction is typically shown in Pascals (Pa), so when you see a rating such as “2000 Pa” for a vacuum, what the heck does that mean?  Is that good, or bad, or what?

I’ll put my engineering hat on and try to explain this in the most practical way possible.   A Pa is the same thing as PSI in that both are measures of pressure, just using different units . They are both a ratio of a Force (F) divided by an Area (A).  However, instead of Pounds divided by Square Inches for PSI, a Pa is Newtons per Square Meter.  A Newton is a force, just as a Pound is, and a Square meter is an area, just as a square inch is.  You can easily google each individual unit to see what the conversion is, but the simplest way to understand how strong a Pascal is is to search  and convert a PSI to a Pa.  

Simply googling this conversion shows that 1 PSI is equal to 6,894 Pa.   Think about the units of a PSI in terms of suction.   1 PSI is enough pressure (or vacuum) to lift an object that weighs 1 Pound if the vacuum is applied over 1 Square inch of that object.       If the same Pressure (or suction) is spread out more, say over 2 square inches, the required vacuum to lift one pound would only have to be half as much since the area of suction is twice as large, and so on.

So, lets look at a typical example of a robot vacuum and how vacuum pressure applies.  If the robot has rating of 3000 Pa, that’s equivalent to 0.435 PSI.  If the size of the robot vacuum is say 10″ x 10″, than the area the vacuum is covering is 100 Square inches.  If the vacuum was applied to the entire area of the cleaning surface, the vacuum would be capable of holding 43.5 Lbs upside down.  Now the vacuum is not spread out over the entire cleaning area, but lets say it was applied to only 25% of the area, the vacuum would be capable of holding 43.5Lbs * 0.25 or 10.8 Lbs.  Now the 10.8Lbs is still not the holding capacity of the robot since the vacuum is not holding the robot upside down, but rather attached to a vertical glass pane, so there is friction that is also helping it from sliding down the glass.  

Calculating the amount of additional holding power friction will add to the vertical holding power of the vacuum is beyond the scope of this article, but it will add a significant amount of safety factor to the numbers discussed above.

So what does all this mean?   A typical robot cleaner might only weigh 3 or 4 Lbs., and the vacuum is holding it on a vertical surface where friction will add to the calculated upside down holding capability, so a rating in the range of  2000 – 3000 Pa represents a very strong vacuum for this application, much more than adequate for any robotic cleaner and will allow for excellent fluid pick up of the cleaning solution.  


There are other factors to consider if you are thinking that a robotic vacuum might be a good idea for your situation.  In addition to Vacuum, there is fall protection for the robot, ups battery back up to hold the vacuum in place in case of a power failure, Artificial Intelligence to pick the most efficient cleaning paths, remote control, Smart Phone App control, Dual Spray, Ultrasonic Spray, and the list goes on.  

I’ve researched and listed what I consider the 5 best robotic vacuum cleaners and made a table of data to help you in your decision making process.   The video below is also a good way to see how these things actually work.  The pricing generally goes from Higher to Lower as you move from from Left to right in the table.  I’ve also included links to check the latest price on Amazon, so take a look and do some of your own additional research, but hopefully this article is helpful.    


From every consideration I have, the HOBOT 2S is a clear winner for my situation (shown in the video below).   I really liked the Ultrasonic Dual Spray, along with the Smart Phone App capabilities.  This unit has nearly every feature available for a residential robot window cleaner.  It may cost a few hundred dollars more than the lower end models, but the capabilities along with the warranty they offer makes it worth it. 

Good Luck and Happy Spring Cleaning!



Unit Size LxWxH (Inches)
9.5 x 9.5 x 3.4
9.4 x 9.4 x 3.3
11.4 X 5.5 X 4.5
11.3 X 5.6 X 3.4
11.4 X 5.6 X 3.4
Vacuum Power (Pa) OR (Vertical KG)
7 Kg
UPS Back-Up
Smart Phone App
Multi Surface
Smart AI
Dual Spray
Yes - Ultrasonic
None - Manual
Fall Protection

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