At a Glance: The Breathesmart 35i vs Core 400s

Here’s a quick side-by-side look at how the Alen BreatheSmart 35i and Levoit Core 400S compare at a glance, so you can get a feel for their strengths and features before diving into the details.

Feature	Alen BreatheSmart 35i	Levoit Core 400S
Price Range	$230-$289	$199-$229
Warranty	Lifetime (with AirID registration)	2 years (with product registration)
Positioning	Premium, sensor-rich purifier	Sleek, affordable, smart-connected purifier
Smart Features	Advanced onboard sensors (PM1, PM2.5, VOC, temp, humidity)	Smart app control, voice assistant compatibility
Coverage Area	Up to 1,000 ft² per hour	Up to 1,980 ft² per hour
Noise Profile	Ultra-quiet, engineered for sound-sensitive spaces	Quiet operation, especially in Sleep Mode
Best For	Long-term use, real-time air quality tracking	Budget-conscious users, smart home integration
Ideal Spaces	Bedrooms, living rooms, shared offices	Bedrooms, living rooms, shared offices

Which Air Purifier Is The Best Mid Range Option?

Feature	Alen BreatheSmart 35i	Levoit Core 400S
Price	$289. Alen is a great long-term value	$229. Levoit wins on price.
Efficiency	Alen wins for specialized filters	Levoit offers more general air cleaning
CADR (Speed)	Alen offers steady, consistent purification	Levoit wins on faster air cleaning
Noise	Alen wins for most quiet at all fan speeds	Levoit has occasional noise at high speeds
Sensors & Monitoring	Alen wins for the most comprehensive air quality data	Levoit has smart home integration and app control
Design & Portability	Alen offers a single shape, but customizable fronts	Levoit wins with a compact column design
Filter Replacement	Alen wins with longer-lasting, targeted filters	Levoit has simple, budget-friendly filters
Overall Recommendation	Alen wins for advanced monitoring, quiet performance, and long-term investment	Levoit is great for affordable, fast, smart air purification

Which Air Purifier Offers Better Filtration and Clean Air Performance – The Levoit or The Alen?

When it comes to filtration and cleaning the air, both the Alen 35i and Levoit Core 400S use solid H13 True HEPA filters, which are great at capturing tiny particles like pollen, pet dander, smoke, and dust mites. So, you’re definitely getting medical-grade filtration with either one.

What I really like about the Alen 35i is how customizable its filter system is. You can choose from different filter types depending on your needs, whether it’s allergies, smoke, odors, or chemical sensitivities. For example, some filters have extra activated carbon for better odor and VOC removal, which is awesome if you’re dealing with wildfire smoke or strong household smells.

The Levoit Core 400S takes a simpler approach with its 3-stage filtration: a pre-filter for the big stuff, a HEPA layer for fine particles, and a carbon layer to handle odors and gases. It doesn’t offer the same filter options as Alen, but for its size and price, it still does a great job of cleaning the air in a straightforward, reliable way.

What $300 Covers: Matching Purifier Cost to Room Size

When comparing the Alen 35i and Levoit Core 400S, it’s important to look beyond the surface-level coverage numbers and consider how well each one can clean a space based on air changes per hour (ACH), which is the number of times the air is fully filtered in a room per hour.

The Alen 35i is designed to clean up to 1,000 square feet every hour at 2 ACH, meaning it completely refreshes the air in that space twice per hour. This makes it a great fit for medium-to-large spaces where air quality is a priority, such as master bedrooms, living rooms, large offices, or even open-plan apartments. If you’re dealing with allergies, pets, wildfire smoke, or chemical sensitivities, that higher filtration rate gives you the continuous protection you need.

The Levoit Core 400S advertises coverage of up to 1,980 square feet per hour, but that’s based on just 1 ACH, aka only one full air exchange per hour. That might be okay for general air freshness in a dining room or home gym, but it’s not ideal for allergy or asthma sufferers. In more realistic terms, for spaces that need 4-5 ACH (like nurseries, kitchens, or rooms with pets), the Levoit is best suited for rooms around 400-500 square feet.

If you’re looking for strong, consistent purification in larger or high-traffic areas, like open living rooms, master bedrooms, or shared spaces, then the Alen 35i is the better fit thanks to its higher air change rate. On the other hand, the Levoit Core 400S works well in smaller rooms like guest bedrooms, offices, or nurseries where basic filtration is enough and cost is a bigger factor.

CADR Comparison: How Fast Do They Clean the Air?

CADR, or Clean Air Delivery Rate, is one of the most important metrics when comparing air purifiers. It tells you how quickly a unit can filter out specific pollutants like smoke, dust, and pollen from the air in a standardized space. Higher numbers indicate faster and more efficient air cleaning.

Let’s see how the Alen 35i and Levoit Core 400S stack up.

CADR Type	Alen BreatheSmart 35i	Levoit Core 400S
Smoke	190 CFM	231 CFM
Dust	190 CFM	240 CFM
Pollen	190 CFM	259 CFM

What Does CADR Mean in Your Home?

The Levoit Core 400S clearly leads in raw CADR across all three categories, particularly for pollen, where it outpaces the Alen 35i by a significant margin. This suggests that Levoit can cycle and purify the air in a given space more rapidly, especially useful during allergy season, high-pollution events, or wildfire smoke exposure.

That said, CADR is only one part of the picture. While Levoit delivers faster air turnover, the Alen 35i’s strength lies in its deeper filter media, longer-lasting filters, and advanced sensor-driven responsiveness. This may result in more consistent purification over time, particularly in rooms with variable pollution sources or chemical contaminants not reflected in CADR scores.

What Should I Pick?

Which Air Purifier Is Quieter – The Alen or The Levoit?

When it comes to noise, I know how important it is, especially if you’re planning to run your air purifier in a bedroom, nursery, or any quiet space. Luckily, both the Alen 35i and Levoit Core 400S are designed to be pretty quiet, but they handle it a bit differently.

Alen BreatheSmart 35i: QuietMark-Certified Precision

The Alen 35i is officially QuietMark certified, meaning it has been independently tested and verified to operate at exceptionally low noise levels across its speed settings. This recognition isn’t just a label, it reflects Alen’s engineering focus on sound-dampening materials, smooth fan mechanics, and consistent airflow design.

At lower speeds, the 35i produces a gentle hum that fades into the background—ideal for uninterrupted sleep or focused work. Even on higher settings, the sound remains soft, low-toned, and non-disruptive. Its ability to deliver powerful purification without harsh motor noise is one of its standout features, making it an excellent fit for sound-sensitive households.

Levoit Core 400S: Quiet Operation Without Certification

While not QuietMark certified, the Levoit Core 400S still performs well when it comes to everyday sound levels. In Sleep Mode, it slows the fan and dims the display lights, offering a quiet experience that’s more than sufficient for most bedrooms. Its compact design and airflow pattern help it run softly on lower settings.

However, at medium to high speeds, the sound profile becomes more noticeable. It’s not overly loud, but the airflow can produce a sharper, higher-pitched tone—especially in acoustically reflective environments like small rooms with hard floors. Still, for its price point and performance level, Levoit does a respectable job of keeping noise under control.

So, which one’s best for you? If you want the quietest possible purifier that won’t disturb your sleep or quiet spaces, the Alen 35i is the way to go. But if you don’t mind a bit more noise when it’s working hard and want to save some money, the Levoit still delivers decent quiet performance.

How Does the Sensor Technology and Air Monitoring Compare?

When it comes to creating healthier indoor environments, it’s not just about cleaning the air, it’s also about understanding it. Both the Alen 35i and Levoit Core 400S are designed to continuously monitor air quality and adjust their performance accordingly, but they take notably different approaches in how much they detect and how that information is shared with the user.

Alen 35i: Full-Spectrum Environmental Awareness

Levoit Core 400S: Smart Simplicity with App Integration

Summary: Intelligence vs. Connectivity

• Alen 35i delivers deeper, broader environmental monitoring, ideal for those who want robust, real-time feedback on air composition, including chemical pollutants.
• Levoit Core 400S offers strong smart-home compatibility and simplified air quality tracking that’s accessible and user-friendly, especially through its mobile app.

Both are capable of improving your indoor air, but Alen is built for users who want a more data-rich and proactive purification experience, while Levoit prioritizes tech convenience and affordability.

One of the biggest differentiators is sensor coverage and how each model tracks and reacts to air quality.

Sensor Technology: What Each Purifier Detects

Understanding the air around you is just as important as cleaning it. Here’s a breakdown of what each unit monitors in real time:

Sensor/Feature	Alen BreatheSmart 35i	Levoit Core 400S
PM2.5 (Fine Particles)	✅	✅
PM1 (Ultrafine Particles)	✅	❌
VOC (Chemical Pollutants)	✅	❌
Temperature Sensor	✅	❌
Humidity Sensor	✅	❌
Auto Mode	✅	✅
App or Voice Control	✅	✅
AirID Registration	✅ (Lifetime Warranty)	❌

Design & Portability

Let’s talk design and portability because your air purifier should fit your space and your style without feeling like an eyesore or a hassle to move around. Here’s how the Alen 35i and Levoit Core 400S stack up when it comes to looks and how easy they are to carry from room to room.

Alen 35i: Customizable, Premium, and Practical

The Alen 35i features a larger, rectangular form factor that’s built for presence and performance. One of its standout design elements is the customizable front panel system, allowing you to match your purifier to your personal style. Choose from five high-quality finishes including warm oak, weathered gray, brushed stainless, graphite, and espresso. These designer panels let your air purifier blend seamlessly with your home décor whether it’s modern, rustic, or industrial.

Beyond aesthetics, the Alen 35i incorporates a built-in, ergonomic carry handle, making it easier to relocate when needed despite its size and premium materials. The solid build and refined finish give it a durable, high-end feel that’s meant to complement living rooms, bedrooms, or office spaces where both function and style matter.

Levoit Core 400S: Sleek, Compact, and User-Friendly

In contrast, the Levoit Core 400S sports a modern cylindrical design with 360° air intake, maximizing airflow efficiency in a smaller footprint. It’s noticeably more compact and lightweight compared to the Alen, which makes it super easy to move from room to room or tuck into tighter spaces like bedside tables or kitchen counters.

Levoit’s minimalist aesthetic leans on clean lines and a matte finish that fits well in contemporary, tech-savvy homes. It prioritizes portability and unobtrusiveness, perfect for users who want a powerful purifier without the bulk.
All in all, Alen is better suited for permanent placements in common areas. Levoit is easier to relocate and blends well into minimalist spaces.

How Easy Is Filter Replacement? A Maintenance Comparison between Alen and Levoit

When choosing an air purifier, it’s essential to consider not just how well it performs out of the box but how easy and cost-effective it is to maintain over time. Both the Alen 35i and Levoit Core 400S use HEPA-grade filters to capture airborne pollutants, but their filter design and customization options differ significantly.

Alen 35i: Modular Filters Built for Specific Needs

The Alen 35i features a multi-layered filtration system that includes:

• Washable Pre-Filter – Captures larger particles like dust, pet hair, and lint to extend the life of the main filter.
• Pure Filter Options – Alen offers a choice of filter types tailored to different air quality needs:
  • Allergies (standard particle filtration)
  • Odor (enhanced activated carbon for smoke or chemical smells)
  • Allergies + Germs & Mold (with antimicrobial coating)
  • Allergies + Pets & Odor (pet dander + odor combo filter)
• Medical-grade H13 True HEPA Core – Captures 99.97% of fine airborne particles down to 0.1 microns, including pollen, mold spores, and dust mites.

This system offers exceptional customizability, allowing users to fine-tune their filter choice based on their environment, whether it’s allergies, wildfire smoke, pet-related odors, or airborne pathogens. Alen filters are also designed for longer life, meaning fewer replacements throughout the year.

Levoit Core 400S: All-in-One Simplicity

The Levoit Core 400S uses a 3-in-1 HEPA-grade filter cartridge, combining:

• A Pre-Filter – Captures larger particles such as dust and hair.
• A HEPA-Grade Filter – Traps fine airborne pollutants like pollen and smoke.
• An Activated Carbon Layer – Helps absorb odors, cooking fumes, and VOCs.

This compact, integrated system is easy to install and replace. The purifier includes a filter change indicator, and the VeSync app also tracks usage to help you stay on top of maintenance. While it lacks the specialized filter options that Alen offers, Levoit’s filter system is convenient, widely available, and budget-friendly.

Bottom Line: Customization vs. Convenience

• Alen 35i gives users greater control and flexibility with its specialized filter lineup, ideal for those with specific sensitivities or changing air quality needs. Its filters are also designed to last longer, reducing how often you need to replace them.
• Levoit Core 400S offers a streamlined, affordable filter system that’s easy to manage and works well for general-purpose air purification.

If you want tailored performance with medical-grade materials, Alen offers more precision and adaptability. If you prefer quick, simple upkeep, Levoit is a strong low-maintenance option.

Which Should You Choose: The Alen 35i or the Levoit Core 400S?

Final Thoughts

Both the Alen 35i and Levoit Core 400S are standout purifiers in their class, but they cater to different priorities:

• Alen excels in longevity, precision air tracking, and overall air wellness.
• Levoit shines with convenience, smart tech, and affordability.

If you’re serious about long-term air health and want full-spectrum sensor feedback, go Alen. If you want an easy-to-use, connected purifier with great performance on a budget, Levoit’s a fantastic pick.