What do the suction force values ​​Pa, kPa or AW mean for vacuum cleaners?

Suction power Suction power Pa kPa AW Air Watt

I often write test reports on vacuum robots, cordless vacuum cleaners or normal mains-operated cylinder vacuum cleaners. In this context, I usually also study the technical data of the vacuum cleaner and keep stumbling over the manufacturer's information on the suction power. While in the past the suction power was often equated with the value of the electrical power consumption and given in watts, units with the abbreviation “Pa” or “AW” are more likely to be found in current cordless vacuum cleaner models.

In this post I would like to go into these values ​​and explain how important (or unimportant) it is to pay attention to a high number of these values ​​when buying a vacuum cleaner. But let's start with the "old" watt and the new unit "Air Watt" ...

What is the difference between Watt and Air Watt?

The question should rather be, what do Watt and Air Watt have in common, because it is not much. Watt is the unit for electrical power. For example, it shows how much electricity a vacuum cleaner needs. However, since this information has little informative value about the suction power of a vacuum cleaner, some manufacturers have started to specify the suction power in Air Watt (AW).

The number for Air Watt - sometimes called Luftwatt - is determined by the negative pressure that the vacuum cleaner can create and the amount of air it can move in a given time. That sounds like a sensible thing, but as with all other values ​​that are currently being quoted by manufacturers, Air Watt does not have any direct information about how great the suction force is at the nozzle, because the suction power can be from the measuring point close to the motor quickly fall off to the nozzle through branches and unwanted openings in the air system.

To make matters worse, Air Watt is not an internationally defined, physical unit. The figures that manufacturers give for Air Watt should not be seen as values ​​that can be directly compared - although they should actually be.

My Dyson V8 Absolute only has a suction power of the equivalent of 6000 Pa (115 AW) in max mode, but thanks to the good air flow and the turbo brush it still removes a lot of hair and dirt - Pa and Air Watt are not everything (photo : Sir Apfelot).

My Dyson V8 Absolute only has a suction power of the equivalent of 6000 Pa (115 AW) in max mode, but thanks to the good air flow and the turbo brush it still removes a lot of hair and dirt - Pa and Air Watt are not everything (photo : Sir Apfelot).

What does the unit Pa say about the suction force?

Pa stands as an abbreviation for the unit Pascal, which is used in physics to indicate a pressure difference. This makes sense because a vacuum cleaner creates a negative pressure to suck in dirt and dust. And the higher the Pa value, the more negative pressure the vacuum cleaner creates and the better the suction power. In short: a lot of "Pa" is good !? No, unfortunately it's not that easy - but more on that below when it comes to the practical values.

The change in the specification of watts (W) to Pascal (Pa) was made sometime after the EU created a law that limits the power consumption of vacuum cleaners to 900 watts. Since one could no longer score with high watt values ​​with consumers (more than 900 watts were no longer allowed), the unit Pa was used, with which one could again play with high numbers for marketing purposes.

The manufacturers were therefore forced to budget with the electrical energy and still generate a high suction power. The vacuum cleaners automatically became more efficient. As a result, specifying the watt value no longer made sense and the specification Pascal (Pa) was established to convey to customers how powerful a vacuum cleaner is.

Interesting contribution on the subject of "suction power":

Conversion of AW (Air Watts) in kPa (Kilo Pascal)

Some vacuum cleaner manufacturers, such as Dyson, indicate the power of their vacuum cleaners in Air Watts (AW). Unfortunately, I could not find an exact conversion into kPA, but the following values ​​were equated at the consumer advice center in South Tyrol:

  • 250 - 400 air watts
  • 1300 - 2200 mm / H2O
  • 13-22 kPa = 13.000-22.000 Pa

That would mean that 1 AW equals 52 Pa. I therefore use these numbers as a rough basis for the conversion to convert Air Watt values ​​into Pa values ​​for my table below with practical values.

For robot vacuum cleaners, values ​​of 4000 Pa are already the current upper limit - if the air duct is poorly designed, a robot vacuum cleaner can clean more effectively with 2000 Pa than one with 4000 Pa (Photo: Sir Apfelot).

For robot vacuum cleaners, values ​​of 4000 Pa are already the current upper limit - if the air duct is poorly designed, a robot vacuum cleaner can clean more effectively with 2000 Pa than one with 4000 Pa (Photo: Sir Apfelot).

Pa values ​​from practice

The manufacturer himself is responsible for measuring the Pa value. There are no rules as to where this value has to be taken with a measuring device. You have a high value directly on the engine, but this can decrease on the way to the nozzle if there are leaks in the air duct.

Accordingly, some “caution” is recommended by manufacturers when specifying the Pa values. Unknown manufacturers in particular may be measured very "optimistically" in order to achieve an advertising effect.

In order to get a feeling for how “good” a vacuum cleaner is, I have brought together a few values ​​that I found on various manufacturer websites.

  • Robot vacuum cleaners work in the range from 2000 to 4000 Pa
  • Cordless vacuum cleaners have between 10.000 and 20.000 Pa
  • Cylinder vacuum cleaners (mains operated) have between 13.000 and 25.000 Pa

Vacuum cleaner with particularly high suction power

For further "entertainment" I have selected a few best-of models here. So a couple of devices that have a particularly high suction power in their class.

Robot vacuum cleaner with 4.000 Pa

Cordless battery vacuum cleaner 25.000 to 30.000 Pa

At this point a tip from me: The Dyson V11 Animal + is expensive and has "only" about 12.000 Pa, but I have a previous model and it has an incredibly good cleaning performance thanks to its motor brush.

Cordless handheld vacuum cleaner Dyson V11 Animal + pet hair vacuum cleaner

If I had to buy a new cordless hand vacuum cleaner at the moment, my choice would be the Dyson V11 Animal +. I have the old V8 Absolute Version and am very satisfied with the device despite the high price (Photo: Amazon).

Mains operated cylinder vacuum cleaners

In the case of cylinder vacuum cleaners, unfortunately, the watt value in the specification of the power is still used. Accordingly, I was unable to make a “best of” selection based on the Pa value.

A selection based on watts, however, does not make sense either, since non-name companies are specifically throwing models on the market that simply have 900 watts of power consumption, but may work very inefficiently. So suction power is by no means to be equated with watts.

I therefore use a test by Stiftung Warentest to make a selection, which also contained cylinder vacuum cleaners with bags or dust boxes. Here are the four best models:

Vacuum cleaner with bag

Cylinder vacuum cleaner with dust box

I hope that with my explanations about the values ​​Watt, kPa, Pa and Air Watt, I was able to help you a little further in researching the right vacuum cleaner for you. Basically, as is so often the case with technical devices: the numbers alone do not say so much. You can use it as a guide, but ultimately the quality of the vacuum cleaner has to be right, because what use is a high Pa value if it was only measured under laboratory conditions and the vacuum cleaner does not pick up bread crumbs in everyday life.

I therefore stick to well-known companies such as Miele, eufy, Bosch, Dreame, Dyson and the like. You are seldom disappointed.


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  1. Hubert says:

    I read that you tried to convert the pressure (pressure difference) into watts. Values ​​are also given.
    However, this can only be data from the data sheet.
    From a physical point of view, one would still need the volume flow and the associated pressure difference. 20 kPa and the volume flow at this pressure difference.
    The equation for the conversion would be
    Power = volume flow times pressure
    In units:
    Power: watt or Nm / sec
    Volume flow: cubic meters / sec
    Pressure: Pa (Pascal), N / m2
    Watt = m3 / sec * N / m2 = Nm / sec = Joule / sec = energy per time

    1kPa = 10 mbar

    It doesn't really help but maybe explains why you can't just convert

    • Jen Kleinholz says:

      Hello Hubert! Thanks for the interjection. It was almost clear to me that the units cannot be converted into each other so easily. But now I have the physical explanation for it. : D

  2. Ilya says:


    I have a problem understanding the explanations here. Normal pressure, i.e. air pressure, is around 1 bar, which corresponds to around 1000 kPa... if a vacuum cleaner creates a vacuum of 6 kPa, that's a stronger vacuum than one that creates 13 kPa, isn't it 😅?

    • Jen Kleinholz says:

      Hello Ilya! I'm not a great physicist either, but I think the negative pressure is the difference to "normal" pressure. In this case, a higher number is better, since a larger pressure difference also means more suction power. If I tell nonsense, I like to be corrected. 😂

  3. Ilya says:

    All right, that would make sense. After a long search I found another source that confirms this.

    Thank you very much for your help.

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