The number that appears most frequently in robot vacuum advertisements is suction power. But Pa (Pascal), W (Watt), AW (Air Watt), CFM (cubic feet per minute) — the units differ by brand, and measurement conditions vary too, making direct cross-product comparison by numbers alone impossible. Rather than being dazzled by suction figures, the first step is to understand how those numbers translate into actual cleaning results.
Why Suction Power Numbers Are Hard to Trust
Suction power figures cited by robot vacuum manufacturers are almost always "maximum suction power." This figure represents the theoretical peak value the motor can achieve, not the sustained suction during actual floor cleaning. As battery charge drops or the filter becomes even slightly clogged, output falls immediately. The more fundamental problem is that there is no unified unit standard. Pa measures suction pressure, while AW reflects both suction pressure and airflow together — comparing the two directly is no different from comparing kilograms and liters.
In the home appliance market, the true meaning of "value for money" is, as IT Donga put it, "a product that delivers more features than other products at the same price range, or one that delivers more utility than expected in a specific use or environment." The same applies to robot vacuums. A higher suction power number does not guarantee high-value cleaning in your home. What matters is whether the specs suit your living environment and lifestyle.
Suction power numbers are marketing language — actual cleaning results are determined by the combination of filter design, brush configuration, and obstacle detection.
Three factors have a more direct impact on cleaning results than suction power. First, the structure of the suction inlet and brush — it is the brush, not the motor, that actually scrapes debris from floor gaps. Second, filter density and replacement frequency — verify whether a HEPA-grade filter is included to prevent re-emission of fine dust, and whether replacement costs will be burdensome in the long run. Third, the cleaning path algorithm — even with the same suction power, an inefficient path with overlaps and gaps reduces cleaning effectiveness.
The 7-Item Pre-Purchase Checklist You Actually Need to Check
The items below are criteria verifiable from manufacturer-disclosed specs and product structure. You can check them directly in-store or on product detail pages online.
| Check Item | What to Verify | Priority |
|---|---|---|
| ① Suction power unit | Which unit — Pa, W, or AW — and compare only within the same unit | Basic |
| ② Filter grade | Whether a HEPA filter is included, replacement frequency and cost | High |
| ③ Brush design | Rubber brush vs. bristle brush, presence of tangle-prevention structure | High |
| ④ Obstacle and drop detection | Type of sensor — LiDAR, camera, or ultrasonic — and detection accuracy | High |
| ⑤ Mop separation mechanism | Whether auto-lifting is present, anti-carpet-contamination structure | Medium |
| ⑥ Dustbin capacity and type | Manual emptying vs. auto-collection station, capacity in liters | Medium |
| ⑦ Battery and area coverage | Cleanable area per charge (sq. m), whether it resumes cleaning after recharging | Basic |
① Suction power units are only meaningful when compared within the same unit. A higher Pa number does not necessarily mean stronger actual suction than a product with a higher AW number. ② For filter grade, those sensitive to allergies or households with pets should target HEPA H13 or above. Some products have annual filter replacement costs in the tens of thousands of won, so long-term maintenance costs must be calculated. ③ For brushes, rubber anti-tangle brushes provide dramatically superior maintenance convenience compared to bristle brushes in environments with long-pile carpet or significant pet hair.
④ Obstacle detection sensor type creates significant performance variation. LiDAR (laser) is accurate even in dark environments but creates a protrusion on top of the unit that may prevent it from fitting under low furniture. Camera-based designs allow slimmer form factors but are sensitive to lighting conditions. ⑤ For models with a mop function, verify whether the mop pad automatically lifts when carpet is detected. Without this, the unit may roll across carpet while wet, causing contamination instead of cleaning it.
Realistic Expectations by Price Range
Robot vacuums fall broadly into three price tiers based on retail price. Under KRW 200,000 budget models are often suction-only or use basic random path patterns. For small spaces with simple obstacles, this tier can still be a practical choice. The KRW 200,000–500,000 mid-range tier is where LiDAR-based mapping, app integration, and a mop function begin to appear in earnest. Cross-referencing the 7-item checklist carefully in this tier will help narrow down the best fit for your environment.
The KRW 500,000+ premium tier adds auto-collection stations, automatic washing and drying functions, and AI-based object-avoidance features. However, these features also raise ongoing maintenance costs — dustbags, cleaning solution, filters, etc. As IT Donga noted in its ice maker article, the "ongoing burden that grows with extended use" is a common pitfall across home appliances — and it applies to robot vacuums too.
A higher price does not necessarily mean a better fit for your home. A studio apartment for one and a 33-pyeong (approximately 109 sq. m) apartment with two pets have fundamentally different requirements. For a studio, paying a premium for battery coverage or auto-collection is overkill. Conversely, in an environment with long-pile carpet and heavy pet hair, choosing a product without rubber brushes based on suction numbers alone means you will spend more time removing hair from the brushes every day.
Who Should Buy Now / Who Should Wait
When buying now is rational
- Your living area is fixed and the flooring type (hardwood, tile, carpet) is already set — you can confirm the right brush and suction design
- Pet hair or allergies make daily cleaning necessary — the automation of a robot vacuum translates into immediate quality-of-life improvement
- You have found a product in the KRW 200,000–500,000 range with all three: LiDAR + mop auto-lift + HEPA filter
- Emptying the dustbin manually 2–3 times per week is not inconvenient — the savings from skipping an auto-collection station are significant
- You are planning to move or renovate soon — if the floor environment changes, the product's suitability changes with it
- You want a premium auto-wash station but have a budget under KRW 500,000 — compromising on specs only increases maintenance hassle
- A successor model to your current candidate has been announced — robot vacuum new models come out 1–2 times a year and previous models see significant price drops
- Your home has many door thresholds, level differences, or low furniture clearance — waiting for a slimmer new model is a better strategy
In conclusion, suction power numbers are only one reference data point in buying a robot vacuum. Match the unit type, cross-reference brush design, filter grade, and obstacle detection against your living environment via the checklist, and the product that passes is ultimately "the robot vacuum that cleans best in your specific home."