Cordless Vacuums · Guide
Air Watts vs kPa: What Cordless Vacuum Suction Numbers Actually Mean
Every cordless vacuum leads with a suction number, but the number is easy to misread. Dyson quotes Air Watts; most rivals quote kPa; Shark often quotes nothing at all. These are different measurements taken different ways, so a bigger figure across brands tells you almost nothing. This guide explains what each unit measures, why sealing and brush design decide real pickup, and why the highest number rarely wins overall.
Air Watts and kPa measure different things
Air Watts (Dyson's unit) combines airflow and suction pressure into one figure, measured through the machine. kPa measures sealed suction, the pressure when the nozzle is blocked, which is only part of the story. There's no shared test standard, so comparing across units is meaningless. Dyson's Gen5detect lists 280 AW; the Levoit LVAC-300 lists 30 kPa. You cannot conclude one is nine times stronger, or even rank them, from those numbers. And Shark's Stratos publishes no suction figure at all, yet our engine scores it 8/10 on measured performance.
The biggest number rarely wins overall
Suction is one axis, not the whole vacuum. The Gen5detect posts the catalog's highest suction score, 9/10, but lands at 6/10 overall. Two things drag it down: at 7.7 pounds it scores 4/10 on handling, punishing on stairs and overhead, and its runtime scores only 5/10. Lighter, longer-running machines with lower suction scores beat it on total value. That is the pattern across the catalog: a strong headline figure gets spent on a body that is heavy or short-winded. Read suction alongside weight and real runtime, never alone.
Sealing and brush design decide real pickup
A suction figure is measured at the motor; what matters is how much survives to the nozzle. A sealed air path loses less along the way and, with sealed HEPA, keeps fine dust from leaking back into the room. All three of our picks are sealed. On carpet, the brushroll does work suction cannot: mechanical agitation lifts embedded grit and pet hair. An anti-tangle brushroll, which every pick here has, keeps long hair from wrapping the bar and choking pickup. A modest number with a good brush and a sealed path often out-cleans a big number without them.
Advertised runtime is an eco-mode number
The minutes on the box are the best case: eco mode with a non-motorized tool. The Gen5detect's 70 minutes, the Stratos's and LVAC-300's 60 each, none reflect real cleaning on the powered floorhead. Switch to max or boost for carpet and pet hair and usable time drops to a fraction, often single digits on the strongest setting. Our engine's runtime scores reflect that reality, not the label: the Gen5detect earns 5/10, the Stratos and Levoit 4/10 each. If you clean a whole floor in one pass, treat the headline minutes as roughly halved, then halved again on boost.
How to read our three picks
Each pick shows the lesson. The Gen5detect ($950) is the suction ceiling at 9/10, the choice if power is everything and 7.7 pounds is acceptable, at 6/10 overall. The Shark Stratos ($430) publishes no figure yet scores 8/10 on suction; its problem is weight, 8.9 pounds and 2/10 handling, so overall it sits at 4.7/10. The Levoit LVAC-300 ($170) lists 30 kPa, which you cannot rank against Dyson's Air Watts; the engine places it at a mid-pack 5/10 suction with easier 6/10 handling, a sensible budget balance at overall 5/10.
Our picks for this
The most powerful Dyson: 280 AW, laser dust reveal, HEPA
$950
6/10
Clean Sense IQ auto-boost with odor neutralizer built in
$430
4.7/10
HEPA filtration and a pet mini-brush for around $170
$170
5/10
FAQ
Is a vacuum with more Air Watts stronger than one with more kPa?
Not necessarily. The two units measure different things and are tested differently, so you can't rank across them. Air Watts blends airflow and pressure; kPa measures sealed pressure only. Compare Air Watts to Air Watts, or kPa to kPa, within a brand or class, and ignore cross-unit comparisons entirely.
Why doesn't Shark publish a suction number?
Many Shark models simply don't list a figure, and that absence tells you nothing about performance. The Shark Stratos publishes no suction spec yet earns 8/10 in our engine's scoring based on measured pickup. Judge these machines on independent testing and real cleaning results, not on whether a marketing number exists.
How much runtime do I really get on max power?
Far less than the box claims. Advertised minutes, 60 to 140 across this catalog, are eco mode with a non-motorized tool. On boost with the motorized floorhead, expect a fraction, often single digits on the strongest vacuums. That's why the high-suction Gen5detect scores only 5/10 on runtime despite a 70-minute rating.
Does higher suction mean better cleaning on carpet?
Only up to a point. On carpet, the brushroll's mechanical agitation lifts embedded dirt that raw suction can't reach, and a sealed air path ensures the suction actually arrives at the nozzle. A vacuum with a modest suction score, a good anti-tangle brush, and sealed HEPA can out-clean a higher number that lacks them.
Should I just buy the highest-suction vacuum I can afford?
Usually not. Suction is one of three axes; weight and real runtime matter just as much for most homes. The Gen5detect has the catalog's top suction score but only 6/10 overall because it's heavy and short-winded on boost. A lighter, longer-running machine often delivers more usable cleaning.
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