When shopping for an upright vacuum, you’ll often hear about two key performance metrics: airflow and suction power. These terms are sometimes used interchangeably in casual conversation, but they actually refer to different aspects of a vacuum’s capability. Understanding the difference is crucial for both everyday consumers and vacuum industry professionals. Is it better to have a vacuum with hurricane-like airflow or one with brute-force suction?
This article defines both metrics and examines how each affects cleaning – from deep carpet vacuuming to bare floor dusting and pet hair pickup – with insights from real testing (including data from Vacuum Wars and other experts). By the end, you’ll know which metric might matter more for your needs and how to interpret vacuum specs meaningfully.
Understanding Airflow and Suction Power
What Is Airflow? (Measured in CFM)
Airflow refers to the volume of air a vacuum moves per unit of time. It’s typically measured in CFM (cubic feet per minute).
Think of airflow as the “wind” flowing through the vacuum. A higher CFM means the vacuum can pull more air (and thus more dirt) every minute through its intake and hose. In practical terms, strong airflow helps carry dust, crumbs, and debris from the floor into the vacuum’s bag or dustbin efficiently (Understanding Vacuum Cleaner Suction vs. Airflow – ThinkVacuums.com).
Airflow is influenced not only by the vacuum’s motor power but also by the design of its air pathways, filters, and bag or canister – anything that air passes through. A restrictive filter or narrow passage can reduce the actual airflow, even if the motor is powerful. Manufacturers usually don’t list CFM for upright vacuums, but reviewers often measure it with an anemometer to see how much air (in CFM) the vacuum moves at the cleaning head or hose.
What Is Suction Power? (Measured in Inches of Water Lift)
Suction power refers to the vacuum’s ability to create a pressure difference and pull matter by force. Suction is often measured as “water lift” in inches (inH₂O).
This measurement comes from laboratory tests where a vacuum is used to lift water in a tube – essentially, it gauges how high the vacuum motor can pull a column of water straight up. If an upright vacuum has, say, 80 inches of water lift, that means its suction is strong enough to raise water up an 80″ tube. In everyday terms, suction is the raw pulling force of the vacuum – it’s what allows the machine to lift heavier dirt particles or cling to a floor. The higher the suction (water lift), the more forcefully the vacuum can pull up debris from surfaces.
High suction is especially noticeable when a vacuum seals to the floor or when using attachments on upholstery (where you often feel the vacuum “stick” due to suction). Unlike airflow, suction can be present even with no air moving (for example, when you block the end of the hose, you feel a strong pull – that’s suction force, even though airflow has dropped to zero at that moment).
The Relationship Between Airflow and Suction
Airflow and suction are related but distinct forces, and a vacuum needs a balance of both for optimal performance. In fact, vacuum engineers talk about a “performance curve”: at one extreme (open airflow with no resistance), you get maximum airflow but minimal suction; at the other extreme (sealed suction with no flow), you get maximum suction but zero airflow
In real use, a vacuum operates between these extremes – some air is always moving, and there’s always some resistance. The concept of “air watts” was developed to capture a vacuum’s output power by combining suction and airflow into one number. By definition, air watts are calculated as:
Air Watts=Airflow (CFM)×Water Lift (inches)8.5\textit{Air Watts} = \frac{\textit{Airflow (CFM)} \times \textit{Water Lift (inches)}}{8.5}Air Watts=8.5Airflow (CFM)×Water Lift (inches)
This formula essentially multiplies airflow by suction (with a conversion factor).
A higher air watt rating implies a good balance of strong suction and ample airflow. For example, many manufacturers (like Dyson) advertise air watts to indicate their vacuums’ cleaning power output rather than just motor watts. However, don’t confuse “air watts” with “airflow” alone – they’re not the same (Understanding Vacuum Cleaner Specifications – BestVacuum.com).
Airflow (in CFM) remains, by itself, one of the most telling indicators of cleaning performance, according to many experts.
The key takeaway is that suction creates the pressure difference to lift dirt, but airflow is what actually carries the dirt away. A well-designed upright vacuum finds an optimal balance: enough suction to pull dirt from the surface and enough airflow to keep it moving into the dustbin.
In summary: suction is the force, and airflow is the volume – you need both force and flow for effective cleaning. Next, let’s see how each metric plays out in real-world vacuuming scenarios.
How Airflow and Suction Affect Cleaning Performance
Deep Carpet Cleaning
Cleaning thick or plush carpets is one of the toughest challenges for an upright vacuum. Dirt and dust get embedded deep between carpet fibers, and pet hair or sand can even work their way down to the carpet backing. In this scenario, airflow often proves to be the decisive factor in performance. High airflow (strong CFM) creates a high-speed stream of air moving through the carpet pile, which helps dislodge and whisk away fine dust that suction alone might not reach.
For instance, some vacuum experts have observed that a vacuum with very high airflow but only modest suction can out-clean one with weak airflow but extreme suction
In one comparison, a classic Kirby upright (a “direct air” vacuum known for high airflow) easily outperformed a Dyson upright on deep carpet pickup, even though the Dyson had far higher sealed suction specs (Suction vs Airflow: No high suction needed to clean well – VacuumLand.org).
The Kirby moved significantly more air (about 120 CFM at the nozzle) but with lower water lift (~32″), whereas the Dyson had sky-high suction (over 100″ of water lift) but less than 60 CFM of airflow at the nozzle. The result was that the Kirby lifted out embedded dirt that the Dyson left behind, illustrating how crucial airflow is for pulling particles from deep in the pile.
That said, suction still matters for carpets – especially for heavier debris like sand or for maintaining performance as the dustbin fills. Strong suction creates a pressure differential at the carpet surface that helps “yank” dirt loose from the fibers (imagine it helping to pop sand or pebbles out from the base of the carpet).
Suction is also what keeps the vacuum head “sealed” to the carpet to ensure the airflow is forced through the carpet and not leaking from the sides. If an upright has insufficient suction, it might struggle to grab heavy grit from the base of the carpet, even if the airflow is decent. Vacuum Wars and other testers often perform “deep clean” tests (e.g., embedding sand in medium-pile carpet and measuring how much is removed in a set time).
Vacuums that excel in these tests tend to be those that combine solid suction with high airflow and a good brushroll to agitate the carpet. In summary, for deep cleaning carpets, airflow is arguably the more critical metric, as it correlates with pulling out fine dust and debris from deep in the fibers.
But it must be paired with enough suction to handle heavy particles and maintain the airflow through the carpet. Upright vacuums built for deep carpet cleaning (for example, certain premium bagged uprights or high-end bagless models) usually emphasize a strong airflow path and a tightly sealed system to maximize both CFM and usable suction at the head.
Bare Floor Performance
On hardwood floors, tile, or other bare surfaces, the dynamics change a bit. There’s no thick fiber for air to flow through, so the vacuum relies on suction at the head to capture dirt directly and airflow to transport it in. For fine dust and light debris on a bare floor, airflow helps sweep the particles in as you pass the vacuum over them, and strong airflow can even pull in dust from slight gaps or grout lines.
However, excessive airflow through a floor nozzle that isn’t well designed can sometimes scatter lightweight debris (imagine a strong draft pushing dry cereal or pet hair around before it gets sucked up). That’s why many hard-floor vacuum attachments incorporate soft brushes or strips: they modulate the airflow and keep debris from blowing away, channeling it into the suction path instead.
When it comes to larger or heavier debris on bare floors (like food crumbs or tracked-in soil), suction power becomes important to lift those particles off the floor. If a pebble is stuck in a floorboard crack, it’s the suction (pressure difference), not just airflow volume, that will yank it out.
High suction also helps when using the hose on bare-floor crevices or along baseboards, where you might be pulling dirt from a gap or corner. One practical example is a crevice pickup test: Vacuum Wars performs a test where coffee grounds are placed in a groove on a hard floor, and the vacuum’s ability to clear that groove is scored.
This kind of test challenges both airflow and suction – airflow to keep the particles moving once dislodged and suction to actually pry them out of the crevice.
Another factor on bare floors is that very high suction in an upright can sometimes be a double-edged sword: if the vacuum head seals too strongly to a flat floor, it can become hard to push or can create a whistle of air trying to get in. Many upright vacuums mitigate this by having adjustable vents or a floor mode that reduces suction slightly to allow some airflow and easy movement.
In general, on bare floors, you want balanced suction (to pick up debris without sticking to the floor) and steady airflow (to carry away dust). Vacuums with specialized hard-floor heads (like those with soft rollers or gentler brushrolls) often perform excellently even with moderate suction because the head design creates an optimal seal and airflow path.
In fact, a well-designed head can sometimes compensate for lower raw specs – for example, certain stick vacuums with soft roller heads pick up everything on hard floors despite lower motor power due to their efficient use of airflow. Still, for uprights, if you see a model advertising both high CFM and high water lift, it’s likely to handle bare floors with ease as long as the airflow is directed properly. Strong suction helps with heavy debris and stuck dirt, while ample airflow ensures no dust is left behind.
Pet Hair Pickup
Pet hair is a notorious challenge – it’s lightweight, but it clings to surfaces (carpet fibers, upholstery, and even hard floors via static). In upright vacuums, removing pet hair effectively is a combination of good brush action and the right balance of suction and airflow. How do our two metrics play in?
On carpets, pet hair tends to get tangled in the pile. Suction power is vital here to pull hair out of the carpet once the brushroll agitates it free. Think of long pet fur that’s woven into carpet fibers – you need a strong pull (suction) to extract it completely. If an upright vacuum has weak suction, you might see pet hair just loosened or shifted around by the brush but not actually lifted into the vacuum.
On the other hand, airflow helps carry those hair strands into the dustbin without clogging. High airflow creates a swift current that can take clumps of fur up the vacuum throat before they resettle. If airflow is too low, loosened pet hair might drop back to the floor or get stuck in the nozzle.
So, for carpeted areas with lots of pet hair, you want enough suction to pry hair from the carpet and enough airflow to immediately whisk it away. Vacuums designed for pets (many advertise “pet” models) often have powered brushrolls to stir up hair and strong motors to maintain suction, plus cyclonic action or good airflow to avoid hair clogging the system.
For pet hair on bare floors, airflow can actually be very helpful because pet hair is so light – a good stream of air will pull tumbleweeds of fur inward.
However, if the vacuum’s airflow is too strong at the front without a way to contain it, it might push fur around (similar to dust on bare floors). That’s where the nozzle design (rubber strips, felt seals, etc.) keeps hair from blowing away. Meanwhile, suction helps once the hair is under the nozzle or at the intake: it provides the grip to lift hair off the surface (especially from cracks or from between floorboards).
On upholstery (like couches or car seats where pet hair sticks stubbornly), it’s largely suction that matters since you often use a handheld attachment – you rely on high concentrated suction to pull hair from fabric. Many upright vacuums, when used with a hose and pet hair tool, benefit from a high “water lift” spec to maintain strong pulling force through that small attachment.
In summary, for pet hair, suction power is critical to dislodge and lift hair from fibers, while airflow ensures the hair travels into the vacuum instead of staying stuck or clogging. A vacuum that balances both (and has a tangle-free brushroll design) will give the best results in a home with shedding pets.
Insights from Testing and Industry Benchmarks
Real-world tests by independent reviewers shed light on how airflow and suction translate into actual cleaning power. Vacuum Wars routinely measures both metrics on upright vacuums to get a fuller picture. We use instruments like a digital anemometer to gauge airflow in CFM and a manometer to measure suction (usually in kPa or converted to inches of water lift).
Importantly, we measure these at the cleaning head or hose, not just at the motor, to reflect the power where it actually matters – at the point of contact with your floor.
This approach can differ from manufacturer specs: for example, a company might advertise suction measured directly at the motor (with no hose or floor head attached), which will be a higher number than what you get with the full vacuum assembled. Vacuum Wars instead tests suction at the brush head, accounting for the real-world design of the vacuum (air pathways, seals, vents).
We also conduct an “unsealed suction” test, which measures usable suction with a slight airflow (not a fully sealed nozzle), to mimic how a vacuum actually operates on a floor.
This reveals how well the vacuum’s design maintains suction when it’s not perfectly sealed – factors like the gaps in the floorhead or any bypass valves influence this.
The image below shows Vacuum Wars testing an upright vacuum’s airflow using a digital anemometer. The vacuum is placed on a custom rig with a flow sensor (visible at the opening) to measure how many cubic feet of air it moves per minute. Higher CFM indicates the vacuum can carry more dirt through its system, which generally aids cleaning performance.
In these tests, airflow varies widely between models, often more so than suction does. Many modern upright vacuums (especially bagless cyclonic models) have very strong sealed suction – it’s not uncommon to see 80–100+ inches of water lift in high-end units.
However, their airflow at the floor head might range from around 50 CFM in weaker models to over 100 CFM in the top performers. For instance, Vacuum Wars’ results have highlighted certain uprights that stand out with a great combination of both metrics. The Shark Stratos Powered Lift-Away, as one benchmark, was noted for having the highest suction and airflow of any Shark upright to date, resulting in top-tier cleaning on both carpets and hard floors.
This suggests that when a vacuum is engineered to maximize both airflow and suction, it tends to perform exceptionally across the board. By contrast, a vacuum that skews heavily to one side (huge suction but low airflow, or vice versa) might excel in specific tasks but lag in others, as we saw in the earlier Dyson vs Kirby example.
It’s also worth noting that actual cleaning performance involves other elements like brushroll agitation, nozzle design, and filtration. A vacuum with average specs can sometimes outperform its raw numbers if, say, its brushroll is very adept at grabbing debris or its nozzle creates a perfect seal on the floor.
The testing community often points out that “it’s all in the head,” meaning a well-designed cleaner head can make the most of whatever airflow/suction is available. For example, a soft roller head on a vacuum can pick up fine dust and large debris with minimal scatter, even if the vacuum’s suction is moderate. Nonetheless, when comparing two vacuums with similar brush design, the one with better airflow and suction usually has the edge.
The consensus from testers and industry pros is that you shouldn’t look at just one metric in isolation; consider both and how they work together in the machine’s design.
Making Sense of Vacuum Specifications
How can consumers use this information when evaluating upright vacuum specs? Here are a few guidelines to keep in mind:
CFM (Airflow)
If a manufacturer or reviewer provides the CFM, remember that higher is usually better for overall cleaning ability. As one industry source puts it, airflow is “by far the most important specification in terms of determining cleaning ability” since it’s the moving air that actually transports dirt.
For uprights, good airflow numbers can be around 50–70 CFM or more at the nozzle (some premium vacuums exceed 100 CFM). However, airflow figures are rarely in product boxes – you’re more likely to find them in third-party reviews or tests. If you do see an airflow spec, ensure it’s measured at the vacuum’s intake (where it matters) and not an unrealistic open-air measurement.
Water Lift (Sealed Suction)
A higher water lift means stronger suction. This spec is more commonly cited for canister or central vacuums, but some upright vacuum manuals might list it. A strong upright might have 80–100 inches of water lift or more, while lightweight or cordless models could have much less.
Suction (water lift) is especially important if you plan to use tools (like for vacuuming drapes, furniture, or car interiors) or if you need to pick up heavier debris like sand or small pebbles. It’s also a good indicator of how performance might hold up as filters get dirty – a vacuum with higher suction can tolerate more resistance before performance drops.
Just note that beyond a certain point, extra suction doesn’t improve cleaning on carpets if the airflow isn’t there to carry the dirt. In other words, 120″ of lift sounds impressive, but if the vacuum only has 50 CFM, it may still struggle with thorough cleaning.
Air Watts
Many vacuum makers (Dyson, for example) use air watts as a composite performance metric. This can usually be trusted as a general indicator – more air watts means more overall suction times airflow at the operating point. For instance, if Vacuum A has 100 air watts and Vacuum B has 200 air watts, Vacuum B should have stronger actual cleaning power.
But be careful: some brands might calculate air watts at different points (hose vs nozzle) or at different settings, so it’s not always apples-to-apples. Still, air watts are more informative than just motor watts or amps because they account for the vacuum’s internal losses and efficiency. Use air watt ratings to compare models within the same brand or line, or if provided by an independent test under identical conditions.
And recall that 1 air watt is almost equivalent to 1 watt of power – so a machine claiming 200 air watts is using a good portion of its input power effectively for suction work.
Motor Watts / Amps
These are not the same as suction or airflow at all, but they’re the most commonly advertised specs.
A typical upright might have a 1200W (10 Amp) motor. This tells you how much electrical power it consumes, not how well it cleans. A more efficient design could use those 1200W to produce higher CFM and lift than a less efficient one.
So, don’t be fooled by a vacuum simply advertising “12 Amps = powerful” – virtually all plug-in uprights use 10-12 Amps because that’s the limit of a household outlet. Instead, look for any info on the actual performance (CFM, water lift, or air watts).
Direct Air vs. Bypass Uprights
You might encounter these terms in industry discussions. A direct air (dirty air) upright is an older style where the dirt goes directly through the fan/blower before any filter or bag (classic examples: old Hoover or Kirby uprights). These often yield extremely high airflow at the floor, which is why some vintage designs deep-clean carpets so well, but they usually don’t tout water lift numbers and might not have HEPA filtration.
Bypass (clean air) uprights are modern designs where the suction fan is separate from the dirt path (dirt goes into a bin or bag first, and only clean air passes over the motor). These can achieve higher sealed suction and use multi-stage filtration, but sometimes at the cost of lower airflow due to those filters. Knowing the design can explain why one vacuum has, say, 120 CFM but only 30″ lift (direct air) and another has 100″ lift but 60 CFM (bypass).
Each design has its merits: direct-air machines excel at carpet airflow, while bypass machines handle fine dust filtration better and maintain suction as filters clog. For consumers, this is a reminder that spec numbers should be viewed in the context of the vacuum’s design and intended use.
Independent Test Reviews
Always consider independent tests and reviews. Specifications are useful, but they don’t always tell the full story. A vacuum with slightly lower specs might perform just as well in your home if its brushroll and nozzle engineering make good use of the airflow it has (some uprights have adjustable height or special floor heads that improve real pickup).
Resources like Vacuum Wars (for detailed lab-style tests) or consumer reviews can highlight if a machine with ostensibly great specs actually cleans well in practice. Use the metrics as a guide, but look for evidence of performance on the surfaces you care about (carpet, hard floors, pet hair, etc.).
Conclusion: Which Metric Matters More?
So, is airflow or suction power more important in an upright vacuum? The honest (and perhaps unsatisfying) answer is that both are important – but it depends on your cleaning needs. If we had to generalize, airflow (CFM) has a slight edge in indicating overall cleaning effectiveness, especially for carpet cleaning and general floor pickup – because airflow is literally what carries dirt into the vacuum.
A vacuum with superior airflow tends to remove more dust and debris in one pass and can cover more area without leaving bits behind. This is why many experts emphasize CFM as the key spec for performance.
However, suction (water lift) becomes crucial for specific situations: grabbing heavy debris, pulling dirt out of crevices, keeping strong pick-up when the dustbin is full or filters are getting dirty, and using attachments where concentrated suction matters. If you frequently use your upright’s hose for edges, upholstery, or car cleaning, you’ll appreciate a model with high suction.
In real-world terms, if you mostly have plush carpets and lots of fine dust or pet dander to remove, you might lean toward a machine known for high airflow. If you have a lot of pet hair or mixed surfaces, including cracks and rugs, strong suction might be a higher priority so that hair and grit don’t stay embedded. Ideally, you want a vacuum that scores well on both metrics – many of the best uprights do, as evidenced by models that top “best vacuum” lists having both excellent airflow and suction
Interpreting vacuum specs comes down to understanding that a balance is needed: don’t be swayed by “peak suction” alone or marketing hype around horsepower or amps. Instead, look for clues about the vacuum’s airflow (CFM or airwatts) and suction together. If only one spec is given, consider what that means in context (e.g., high air watts implies a good combo of the two; high amps without other info might not mean much).
In summary, an upright vacuum cleaner cleans best when it has enough suction to lift debris and enough airflow to carry it away. Airflow might be the MVP for most floor cleaning tasks, but suction is the unsung hero that keeps that airflow effective under varying conditions. By understanding both metrics, you can cut through the spec sheets and marketing and make an informed choice.
Whether you’re a consumer wanting a cleaner home or an industry professional designing the next vacuum, remembering the teamwork of airflow and suction – and checking credible tests like those from Vacuum Wars – will ensure you focus on what truly matters for performance. Both metrics matter; the trick is getting them in balance for your specific cleaning challenges.
Frequently Asked Questions
What is the difference between airflow and suction in a vacuum cleaner?
Answer: Airflow refers to the volume of air a vacuum moves, usually measured in CFM (cubic feet per minute), while suction refers to the vacuum’s ability to create a pressure difference, typically measured in inches of water lift. Airflow carries debris through the vacuum system, and suction helps lift dirt from surfaces. Both are essential, but airflow is often more closely tied to cleaning effectiveness.
Is airflow or suction more important for vacuuming carpets?
Answer: For deep carpet cleaning, airflow is typically more important because it helps dislodge and carry fine dust and debris from deep within the fibers. However, suction is also crucial for lifting heavier particles and maintaining a strong seal on carpet surfaces. A balance of both metrics usually delivers the best performance.
What is a good CFM for an upright vacuum?
Answer: A quality upright vacuum typically offers 50 to 70+ CFM at the floorhead, with premium models exceeding 100 CFM. High airflow improves the vacuum’s ability to transport dirt efficiently, making it a key indicator of overall cleaning power—especially on carpets and hard floors.
Why does high suction alone not guarantee better vacuum performance?
Answer: High suction (measured in inches of water lift) provides strong pull, but without sufficient airflow, the vacuum may struggle to carry debris into the dustbin. A vacuum needs both suction to lift dirt and airflow to remove it from the surface. Relying solely on suction can lead to poor cleaning results, especially in real-world conditions.
What are air watts in vacuums, and do they matter?
Answer: Air watts combine both airflow and suction into a single performance metric, offering a more complete picture of a vacuum’s actual cleaning power. Higher air watts generally indicate better efficiency and stronger performance. This measure is especially helpful when comparing vacuums from the same brand or product line.
