You are comparing two cordless vacuums. One says “150 Air Watts.” The other says “25,000 Pa.” A third says “550W.” They all sound impressive. But are any of these numbers actually comparable? And more importantly, which one tells you how well the vacuum will clean your floor?
The short answer is that none of them tell you the whole story, and one of them is actively misleading. The longer answer involves a standards battle that has confused consumers for years and is only now beginning to resolve.
What Each Unit Actually Measures
Watts (W) is the easiest to understand and the least useful for comparing cleaning performance. It measures electrical power consumption. A 550W vacuum uses more electricity than a 350W vacuum, but it does not necessarily clean better. Two vacuums with the same wattage can perform very differently depending on motor efficiency, airflow design, and filtration losses [citation:7]. Watts tell you how much electricity the motor draws, not how much suction reaches the floor.
Pascals (Pa) measures suction pressure, which is the force the vacuum can exert to pull air in. It is a single variable. A high Pa number means the vacuum can create a strong pressure differential, but it says nothing about how much air volume is moving. A vacuum with very high pressure and very low airflow will not pick up much dirt, because there is not enough air moving to carry debris into the bin [citation:3]. This is the core problem with Pa as a marketing number. It can be inflated to look impressive without reflecting actual cleaning ability.
Air Watts (AW) is the most meaningful of the three because it combines both variables. It is calculated by multiplying airflow (in cubic meters per second) by suction pressure (in Pascals) . The result represents the actual power of the air stream—the energy available to lift dirt and carry it into the dustbin. Two vacuums with the same Air Watt rating will have essentially the same suction power, regardless of how much electricity their motors consume .
The formula matters because it explains why Pa alone is insufficient. Airflow without pressure is a breeze. Pressure without airflow is a sealed vacuum with no pickup. Air Watts captures the product of both, which is why it correlates more closely with real cleaning performance.
The Standards Behind the Numbers
Two major standards govern how vacuum air performance is measured, and they use different units.
ASTM F558, the American standard, specifies test methods for determining suction, airflow, air power, maximum air power, and input power under standard operating conditions. The standard explicitly notes that the plenum testing method is “an ideal air performance measurement and is not intended to represent the actual air performance during carpet or floor cleaning” [citation:1][citation:5]. In other words, even a well-executed ASTM test measures potential, not real-world results. The Air Watt unit is associated with this ASTM framework [citation:3].
IEC 62885-2, the international standard, covers both mains-operated and cordless dry vacuum cleaners. The 2026 edition includes a specific annex for cordless products, intended to make their results comparable to mains-operated machines [citation:6]. The IEC framework defines suction power in Watts, calculated as airflow multiplied by vacuum pressure—the same fundamental formula as Air Watts [citation:3].
The distinction between ASTM Air Watts and IEC Watts is largely semantic. A Korean government notice explicitly states that the two are “1:1 comparable” because they use the same test method and calculation [citation:3]. The real problem is not the difference between AW and W. It is the use of Pa, which measures only one of the two variables required to calculate actual suction power.
The Korean Crackdown: When Marketing Numbers Collide With Reality
In September 2025, the Korea Consumer Agency and the Korea Testing Laboratory published a investigation that should be required reading for anyone shopping for a cordless vacuum. They tested ten cordless vacuums sold in Korea and compared the advertised suction figures against measured performance [citation:8].
The results were stark. Samsung, LG, and Dyson, which label their products in Watts or Air Watts, all measured above 280W of actual suction power. Six Chinese brands that labeled their products in Pascals measured between 58W and 160W. Two of them, Roborock and Xiaomi, measured just 72W and 82W respectively [citation:8].
The consumer agency’s conclusion was blunt: using Pa to label suction is “inappropriate and likely to mislead consumers” because vacuum pressure is only one parameter affecting suction and excludes airflow entirely [citation:8]. The agency recommended that eight importers correct their labeling, and the Korean national standards body announced plans to adopt a national standard aligned with IEC [citation:3].
This is not a case of some brands being dishonest and others being honest. It is a case of different units measuring different things, and one unit—Pa—being systematically better at making a product look powerful without actually being powerful.
How to Compare Vacuums When the Units Don’t Match
If you are comparing a vacuum rated in AW against one rated in Pa, you cannot convert between them without knowing both the airflow and the pressure for each machine. The conversion is not a simple multiplier. It depends on the specific operating point of the vacuum.
The practical approach is to prioritize units in this order: Air Watts or IEC Watts first, then Pa as a secondary reference, and ignore motor Watts entirely for performance comparison.
A vacuum rated at 150 AW or 150W (IEC) is in the range that independent testing suggests is sufficient for cordless stick vacuums on hard floors and light carpet [citation:13]. A vacuum rated at 25,000 Pa might be excellent or mediocre, depending on how much airflow it produces at that pressure. Without the Air Watt figure, the Pa number is a partial answer to a two-part question.
There is one more caveat worth remembering. Even Air Watts is a laboratory measurement under ideal conditions. ASTM F558 explicitly states that its results do not indicate actual air power during cleaning, because the floor head, the surface being cleaned, and the seal against the floor all affect real-world performance [citation:10]. A vacuum with excellent Air Watts and a poorly designed floor head can underperform a vacuum with lower Air Watts and better airflow engineering.
What This Means for Buyers and Manufacturers
For a home vacuum cleaner manufacturer, the unit you print on the box is not a neutral choice. It signals what you want consumers to compare. A brand that prints Air Watts is inviting comparison on actual cleaning power. A brand that prints Pascals is inviting comparison on a number that can be made to look large without corresponding performance.
The regulatory trend is moving toward harmonization. Korea is adopting IEC-aligned standards. The IEC 62885-2:2026 edition includes specific provisions for cordless vacuums to make their results comparable to corded machines . The direction is clear: the industry is being pushed toward a single, meaningful metric.
Until that happens, the consumer’s best defense is to look for Air Watts or IEC Watts, treat Pa as a partial specification, and ignore motor wattage entirely. The vacuum that cleans your floor is the one that moves air, not the one that draws the most electricity or creates the highest pressure in a sealed chamber.
FAQ: Your Top 5 Questions About Vacuum Suction Units
1. What is the difference between Air Watts and Pascals?
Air Watts measures actual air power by multiplying airflow by suction pressure. It reflects the energy available to lift and carry dirt. Pascals measures only suction pressure, one of the two variables. A high Pa figure without corresponding airflow does not mean strong cleaning performance [citation:3].
2. Which unit is most reliable for comparing cordless vacuums?
Air Watts (AW) or IEC Watts (W). Both use the same fundamental formula (airflow × pressure) and are directly comparable. The Korean Consumer Agency investigation found that brands using W or AW labels had measured suction above 280W, while brands using Pa labels measured as low as 72W [citation:8].
3. Why do some brands use Pascals if it is misleading?
Because Pa numbers are large and look impressive. A vacuum rated at 25,000 Pa appears more powerful than one rated at 150 AW to a consumer who does not know the difference. The Korean agency explicitly stated that Pa labeling “makes consumers mistakenly believe the product performance is better” [citation:3]. Regulatory pressure is now forcing a shift toward W.
4. Can I convert Pascals to Air Watts?
Not directly. The conversion requires knowing the airflow (in cubic meters per second or liters per second) at the same operating point. Air Watts = Pascals × airflow (in m³/s). Without the airflow figure, you cannot calculate the Air Watt equivalent from a Pa rating alone.
5. Does higher Air Watts always mean better cleaning?
Not always. Air Watts measures potential air power under laboratory conditions. Real-world cleaning also depends on floor head design, brush roll effectiveness, sealing, and the surface being cleaned. ASTM F558 explicitly states its results “do not indicate the actual air power present during the cleaning process” [citation:10]. Use Air Watts as a starting point, but check independent cleaning tests for real-world performance.
